JP2011014374A - Light guide plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light guide plate which controls an emission angle of an incident light beam and make sunlight reach a back of a room with a terrace in winter as a roof material of the terrace.SOLUTION: A prism surface 3 is arranged on at least one side of a transparent resin plate 2, wherein the prism surface 3 has a structure formed by sequentially arranging unit prisms 3a, each of which is a triangular prism having a triangle cross section in a width direction, side by side. One base angle α of the triangle cross section of the unit prism 3a for structuring the prism surface 3 is 3-9°, and another base angle β is 60-90°.

Description

  The present invention relates to a light guide plate that can be suitably used as a roofing material for a terrace.

  In order to brighten the room using daylight, it is generally necessary to increase the opening area of the window. However, a large opening area cannot be easily obtained in terms of a decrease in the seismic strength of the building due to an increase in openings and cost. In addition, the large opening area may cause a rise in indoor temperature in summer and a decrease in heat insulation effect in winter.

  Therefore, the opposite surface of the terrace roofing material on the light incident side is made into a symmetrical prism shape, so that the sunlight in the south and mid-high altitudes in the summertime is reflected to the light incident side by total reflection in the prism, and the south side of the wintertime is reflected. A method is known in which sunlight at low intermediate altitude is transmitted to the prism shape side so that the terrace roofing material is daylighted in winter while suppressing the temperature rise in the room in summer (Patent Document 1).

  Further, a method has been proposed in which the light incident side of the terrace roofing material is formed into a left-right asymmetric lens-shaped surface, and further this resin plate is attached to the window portion so that the light is taken into the interior of the room (Patent Document 2).

Japanese Utility Model Publication No. 62-054124 JP-A-5-59402

The purpose of providing a terrace at the opening is, for example, to prevent direct sunlight in the summer and to function as a sunshade that prevents the indoor temperature from rising, to provide a space to hang laundry, and to place chairs and tables. There are various purposes, such as the purpose of providing a relaxing space under the open air and the purpose of providing a space for enjoying gardening, but in either case, it is almost always desirable to provide it in a sunny place such as the south side of the main building.
However, when a terrace is provided in a sunny place such as the south side of the main building, there is a problem that in winter, sunlight is blocked by the roof of the terrace and the room becomes dark. In particular, in a room with a terrace, it was pointed out that the sunlight could not be inserted, the sunlight could not reach the center of the room, and the entire room became dark or the temperature of the room dropped rapidly.

For example, in the method disclosed in Patent Document 1, the light refracted in the winter is refracted in the downward direction of the terrace, resulting in a decrease in daylighting in the room. There was a problem that the temperature difference between the window and the back of the room was increased.
Further, in the method disclosed in Patent Document 2, when a lens-shaped surface is provided on the incident light surface side, dust and raindrops scattered in the atmosphere adhere to the valley portion of the lens-shaped surface, so that the prism However, it is predicted that it will be difficult to put to practical use because of an increase in cost and weight.

  Therefore, the present invention is a new light guide plate that can control the emission angle of incident light and can reach the back of the room where the terrace is provided in the winter when used as a roofing material for the terrace. Is intended to provide.

  The present invention includes a prism surface 3 having a configuration in which triangular prism-shaped unit prisms 3a having a triangular cross-section are continuously arranged in the width direction on at least one side of the transparent resin plate 2, and the prism surface 3 is provided. A light guide plate is proposed in which one of the unit prisms 3a has a bottom angle α of 3 ° to 9 ° and the other bottom angle β is 60 ° to 90 °.

If the light guide plate has such a configuration, the emission angle of incident light can be controlled. For example, when it is used as a roofing material for a terrace, the solar light reaches the back of the room where the terrace is provided, particularly in winter. Can be achieved, the room is brightened, and a rapid temperature drop in the room can be suppressed.
As described above, since the light guide plate of the present invention can control the emission angle of incident light, it is particularly suitable as a roofing material for terraces, roofing materials such as fences, terrace front panels, louvers and fences, It can be used as a face material for a balcony or the like, and can be suitably used as another daylighting material.

It is sectional drawing which showed an example of the light-guide plate of this invention. It is sectional drawing to which the prism surface of the light-guide plate shown in FIG. 1 was expanded. It is the perspective view which showed an example of the light-guide plate of this invention. It is sectional drawing which showed the model example of the angle which the said light ray advances when the sunlight ray injects into the light-guide plate of this invention, (A) is a summer model, (B) is a winter model. It is sectional drawing which showed the modification of the light-guide plate of this invention. It is sectional drawing which expanded and showed an example of the unit prism of the light-guide plate of this invention. It is the figure which showed the dimension etc. of the roof material of the carport assumed in the simulation test of an Example.

  Next, this invention is demonstrated based on embodiment. However, the embodiment described below is an example of the embodiment of the present invention, and the scope of the present invention is not limited to the following embodiment.

<Configuration of the light guide plate>
The light guide plate (referred to as “the present light guide plate”) 1 of the present embodiment includes a prism surface 3 on the lower surface side of the transparent resin plate 2 and an ultraviolet ray on the upper surface side of the transparent resin plate 2 as shown in FIGS. A plate body or a sheet body provided with the absorption layer 4. However, the ultraviolet absorbing layer 4 is not necessarily provided.

(Transparent resin plate 2)
There are no particular restrictions on the material of the transparent resin plate 2. A transparent resin generally used as an exterior building material can be used. For example, transparent resin materials such as polycarbonate resin, polyester resin, methacrylic resin, styrene resin, polyvinyl chloride resin, polyolefin resin, and polyamide resin can be used. One or two or more of these may be mixed. Among these resins, polycarbonate resins are preferable in terms of transparency, heat resistance, impact resistance, and the like.

The polycarbonate-based resin is a linear polymer containing a carbonate ester bond in the main chain. For example, various dihydroxy diaryl compounds and phosgene are reacted by a phosgene method, or a dihydroxy diaryl compound and a carbonate ester such as diphenyl carbonate Is a polymer that can be obtained by reacting with a transesterification method. Specifically, a polycarbonate resin produced from 2,2-bis (4-hydroxyphenyl) propane (“bisphenol A”) can be exemplified, but the present invention is not limited thereto.
The molecular weight of the polycarbonate resin is not particularly limited. Those having a viscosity average molecular weight of about 15,000 to 30,000 that can be formed into a sheet by ordinary extrusion are preferred.

  Examples of the polyester resin include polyethylene terephthalate, polybutylene terephthalate, polyacrylate, polyether ether ketone, and the like.

  Examples of the methacrylic resin include polymers composed of various esters of methacrylic acid or copolymers with other monomers. For example, homopolymers of various methacrylates such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, and copolymers of these methacrylates with various acrylic esters, acrylic acid, styrene, α-methylstyrene, etc. Etc.

  Examples of the styrene resin include a polymer made of a styrene monomer or a copolymer using a monomer copolymerizable with the styrene monomer. Examples of the styrenic monomer include styrene, α-methylstyrene, styrene derivatives in which a hydrogen atom of a benzene nucleus is substituted with a halogen atom or an alkyl group having 1 to 2 carbon atoms, specifically, styrene, o -Chlorstyrene, p-chlorostyrene, 2,4-dimethylstyrene, t-butylstyrene and the like. Examples of copolymerizable monomers include acrylonitrile monomers such as (meth) acrylonitrile, α-chloroacrylonitrile, vinylidene cyanide, (meth) acrylic acid, methyl (meth) acrylate, (meth) (Meth) acrylic acid such as ethyl acrylate, butyl (meth) acrylate, glycidyl (meth) acrylate, (meth) acrylic acid-2-ethylhexylbutyl, (meth) acrylic acid-β-hydroxyethyl, and these Various esters or vinyl acetate, vinyl chloride, vinylidene chloride, vinyl pyrrolidone, (meth) acrylamide, maleic anhydride, itaconic anhydride, maleimide and the like can be mentioned.

  Examples of the polyvinyl chloride resin include a vinyl chloride homopolymer, a vinyl chloride copolymer obtained by copolymerizing a small amount of a comonomer, a graft copolymer, and the like. Polymer blends of these with vinylidene chloride resin, ethylene / vinyl acetate copolymer, chlorinated polyethylene and the like may be used.

  Examples of the polyolefin resin include a homopolymer of α-olefin or a copolymer of α-olefin and another copolymerizable monomer. Examples include polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-butene copolymer, ethylene-4-methyl-1-pentene copolymer, ethylene-vinyl acetate copolymer, and ethylene-acrylic acid copolymer. It is done. Among these, low density polyethylene having a density of 0.910 to 0.935, ethylene-α-olefin copolymer, and ethylene-vinyl acetate copolymer having a vinyl acetate content of 30% by weight or less are excellent in transparency and weather resistance. ing. Among them, an ethylene-vinyl acetate copolymer having a vinyl acetate content of 5 wt% to 30 wt% is particularly excellent in transparency, flexibility and weather resistance.

  Examples of the polyamide-based resin include nylon-6, nylon-66, nylon-12, nylon-46, and the like.

The transparent resin plate 2 may contain one or two or more of substances that absorb near infrared rays, such as sulfur, sulfur compounds, copper compounds, and other near infrared ray absorbing substances. However, it does not need to be contained.
At this time, as the sulfur, a commercially available sulfur powder or the like can be used. For example, sulfur powder made by Tsurumi Chemical Co., Ltd. (JIS grade 2 equivalent) can be used.
Examples of sulfur compounds include lead sulfide and thiourea derivatives.
Examples of the copper compound include copper stearate, copper sulfide, phthalocyanyl copper and the like.
Examples of other near infrared ray absorbing substances include tungsten hexachloride, tin chloride, chromium, cobalt complex salts, anthraquinone derivatives, and the like.
The content of such a near-infrared absorbing material is not particularly limited, but it is preferable to contain 0.01 to 6 parts by weight in 100 parts by weight of the transparent resin. If the content is 0.01 to 6 parts by weight, preferably 0.01 to 2 parts by weight, particularly preferably 0.01 to 1 part by weight, the light absorption performance in the near infrared region is excellent, and the visible light transmittance is high. Is expensive.

  In addition, the transparent resin plate is softened as long as it does not impair the effects of the present invention, a heat stabilizer, an ultraviolet absorber, a colorant, a fluorescent brightener, a release agent, an antiblocking agent (silica, crosslinked polystyrene beads, etc.) It may contain additives such as materials and antistatic agents.

(Prism surface 3)
1 to 3, the prism surface 3 is provided on the lower surface side of the transparent resin plate 2, that is, on the side opposite to the light incident side of the light guide plate 1, and has a long triangular prism shape with a triangular cross section. The unit prisms 3a are arranged in parallel in the width direction.

As shown in FIGS. 1 and 2, the unit prism 3a preferably has a wedge shape composed of an upstanding side and an inclined side that is gently inclined with respect to the upright side when viewed in a cross section perpendicular to the length direction. It is preferable that one bottom angle α constituting the triangular unit prism 3a is 3 ° or more and 9 ° or less, and the other bottom angle β is 60 ° or more and 90 ° or less.
When the light guide plate 1 having such a prism surface 3 is processed into a roof material for a terrace, for example, as shown in FIG. 4B, it enters when the angle of the sun is lowered in winter. The sunlight can be greatly changed (for example, about 3 ° to 17 °) to allow the sunlight to reach the interior of the room where the terrace is provided. As shown in FIG. 4A, the altitude of the sun is high in the summertime. The incident light can be transmitted without greatly affecting the angle of the incident sunlight.
From this viewpoint, the bottom angle α of one of the unit prisms 3a is more preferably 4 to 9 °, and more preferably 6 to 8 °. The other bottom angle β is more preferably 70 ° to 90 °, and more preferably 80 to 90 °.

  The top of the unit prism 3a may be rounded as shown in FIG. In that case, it is preferable that the curvature radius R of the top part is larger than 0 mm and 0.5 mm or less. From the viewpoint of the light guide property that bends the angle of the light ray incident on the light guide plate 1, the radius of curvature of the top is preferably as small as possible. If it exceeds 0.5 mm, the desired light guide performance may not be obtained. From this viewpoint, it is particularly preferably 0.3 mm or less, particularly 0.2 mm or less.

Moreover, it is preferable that the space | interval (prism pitch) L between the adjacent unit prisms 3a and 3a is 1.5 mm-18 mm. When the prism pitch L is less than 1.5 mm, the ratio of the curved portion (R portion) increases, so that the light guide performance may be lowered, and the pitch of the mold for shaping the prism increases. As a result, fine processing is required to manufacture the mold, making it difficult to perform processing. On the other hand, when the prism pitch L exceeds 18 mm, the groove between the unit prisms 3a and 3a becomes deep, and the strength of the light guide plate is lowered.
From this viewpoint, the prism pitch L is particularly preferably 2 mm to 10 mm, and particularly preferably 2 mm to 5 mm.

  The height H of the unit prism 3a is determined by the bottom angles α and β of the unit prism 3a and the prism pitch L, and is preferably 0.2 mm to 3.0 mm, particularly 0.2 mm to 1. Is preferably 0.0 mm, and more preferably 0.2 mm to 0.7 mm.

(UV absorbing layer 4)
The ultraviolet absorbing layer 4 can be formed by mixing an ultraviolet absorbing material with a transparent resin.

  At this time, as the transparent resin, the transparent resin mentioned as the material of the transparent resin plate 2 can be used. Among these, it is preferable to use the same resin as the transparent resin plate 2 in consideration of adhesiveness, light scattering at the interface, and the like.

  Further, the ultraviolet absorbing material is not particularly limited as long as it has ultraviolet absorbing performance, and for example, benzotriazole, triazine and the like can be suitably used. However, it is not limited to these.

(Layer structure)
The thicknesses of the transparent resin plate 2 and the ultraviolet absorbing layer 4 are not limited as long as there is no problem in surface hardness and moldability, and the thickness ratio is also the same. Generally, the thickness of the transparent resin plate 2 is preferably 0.5 mm to 5.0 mm, particularly 1.0 mm to 3.5 mm, and particularly preferably 1.5 mm to 3.0 mm. Is preferably 10 μm to 100 μm, more preferably 20 μm to 70 μm, and particularly preferably 20 μm to 40 μm.

As long as the light guide plate 1 includes the transparent resin plate 2 and the ultraviolet absorption layer 4 as described above, the light guide plate 1 may include other layers. For example, a near-infrared absorbing layer may be provided. In this case, the above-described ultraviolet absorbing substance can be mixed with the transparent resin mentioned as the material of the transparent resin plate 2.
Alternatively, a prism sheet having the prism surface 3 on one surface side of the sheet body may be formed separately from the transparent resin plate 2, and the prism sheet may be laminated on the transparent resin plate 2.

  Further, as shown in FIG. 5, the light guide plate 1 may be curved upward and bulge when viewed in a cross section orthogonal to the length direction of the unit prism 3 a. In this case, the bottom angle α of the unit prism 3a may be 3 ° or more and 9 ° or less, and the bottom angle β may be a constant angle within a range of 60 ° or more and 90 ° or less, or an appropriate angle within such a range. May be changed.

<Manufacturing method>
As a method of laminating the transparent resin plate 2 and the ultraviolet absorbing layer 4, a sheet provided with the ultraviolet absorbing layer 4 may be laminated on the transparent resin plate 2 obtained by shaping the prism surface 3 in advance. After the resin constituting the transparent resin plate 2 (referred to as “transparent resin plate constituting resin”) and the resin constituting the ultraviolet absorbing layer 4 (referred to as “ultraviolet absorbing layer constituting resin”) are coextruded and laminated, the prism surface 3 may be shaped.

When coextruding the transparent resin plate constituent resin and the ultraviolet absorbing layer constituent resin, for example, a main extruder for extruding the transparent resin plate constituent resin and a sub-extruder for extruding the ultraviolet absorbing layer constituent resin (usually the main extruder) Preferably smaller than the machine).
At this time, if a polycarbonate resin is used as the main component resin of the transparent resin plate constituting resin and the ultraviolet absorbing layer constituting resin, the temperature condition of the main extruder is usually 250 to 290 ° C., particularly 260 to 280 ° C. The temperature condition of the sub-extruder is usually 250 to 290 ° C, particularly preferably 260 to 280 ° C.
In order to remove foreign substances in the resin, it is preferable to install a polymer filter upstream of the T-die of the extruder.

In addition, as a method of laminating two types of molten resins by coextrusion, known methods such as a feed block method and a multi-manifold method can be used.
In the case of the feed block method, the molten resin laminated in the feed block is guided to a sheet forming die such as a T die, formed into a sheet shape, and then flowed into a forming roll (polishing roll) whose surface is mirror-finished. And a mirror finish and cooling while passing through the forming roll, thereby forming a laminate.
On the other hand, in the case of the multi-manifold system, the molten resin laminated in the multi-manifold die is formed into a sheet shape inside the die in the same manner as described above, and then surface finishing and cooling are performed with a forming roll to form a laminated body. can do.
The temperature of the die is usually 230 to 290 ° C., preferably 250 to 280 ° C. if the polycarbonate resin is used as the main component resin of the transparent resin plate constituting resin and the ultraviolet absorbing layer constituting resin, and the molding roll temperature As, it is 100-190 degreeC normally, Preferably it is 110-180 degreeC. As the roll, a vertical roll or a horizontal roll can be appropriately used.

  As a method for shaping the prism surface 3, for example, when the transparent resin plate 2 is extruded or when a laminated sheet of the transparent resin plate 2 and the ultraviolet absorbing layer 4 is co-extruded, a predetermined prism surface is used. The prism surface 3 can be shaped by pressing and cooling the metal roll engraved so that 3 can be imprinted against the extruded transparent resin plate 2.

<Application>
The light guide plate 1 is particularly suitable for processing into a roof material for a terrace. At this time, as shown in FIG. 4, the prism surface 3 of the light guide plate 1 is positioned on the side opposite to the light incident side, and the light guide plate 1 is placed in a direction in which the inclined surface of the unit prism 3a is further inclined. Inclined, in other words, the light guide plate 1 is inclined so that the upright piece is positioned above the inclined side in each unit prism 3a. In other words, in each unit prism 3a, the bottom angle β side is the bottom angle. The light guide plate 1 is preferably used so as to be inclined so as to be located obliquely above the α side.

By processing this light guide plate 1 into a roofing material for a terrace and installing it in this way, as shown in FIG. 4 (B), when the angle of the sun is lowered in winter, the incident sunlight rays are greatly changed. (For example, about 3 ° to 17 °), sunlight can reach the interior of the room where the terrace is provided. As shown in FIG. 4 (A), when the altitude of the sun rises, it is incident It can be transmitted without greatly affecting the angle of incoming sunlight.
At this time, the inclination angle of the light guide plate 1 is not particularly limited. For example, in the cross section orthogonal to the length direction of the unit prism 3a, the south side is preferably set so that the light guide plate is inclined by 0 to 20 °. It is preferable to arrange it so as to be inclined. It has been confirmed that similar effects can be obtained when tilted in this way.

  Moreover, although the installation direction of the light guide plate 1 is not particularly limited, it is preferable to direct the length direction of the unit prism 3a in the east-west direction. However, the “east-west direction” in this case is intended to include a case where the position is shifted within ± 30 ° from true east or true west, preferably within ± 20 °, particularly preferably within ± 10 °. It is meant to encompass the case where it is deviated.

  Since the light guide plate 1 can change the angle of sunlight as described above, for example, in addition to roofing materials for terraces, roofing materials such as fences, surface materials such as terrace front panels and louvers, fences, balconies, etc. It can be suitably used as a daylighting material.

<Explanation of terms>
In this specification, “X to Y” (X and Y are arbitrary numbers) means “X or more and Y or less” unless otherwise specified, and “preferably larger than X” or “preferably "Is smaller than Y".
In addition, when “X or more” (X is an arbitrary number) or “Y or less” (Y is an arbitrary number), it is “preferably greater than X” or “preferably less than Y”. Includes intentions.

  In general, "film" refers to a thin flat product that is extremely small compared to its length and width and whose maximum thickness is arbitrarily limited, usually supplied in the form of a roll. (Japanese Industrial Standards JISK6900), “sheet” generally refers to a product that is thin by definition in JIS and whose thickness is small and flat instead of length and width. However, since the boundary between the sheet and the film is not clear and it is not necessary to distinguish the two in terms of the present invention, in the present invention, even when the term “film” is used, the term “sheet” is included and the term “sheet” is used. In some cases, “film” is included.

  In the present invention, the “terrace” broadly includes a covered space installed beside a house, and includes, for example, a veranda, a balcony, a terrace, a solarium, a balcony, and the like.

  EXAMPLES Hereinafter, although this invention is demonstrated based on an Example, this invention is not limited to these Examples.

<Example 1>
An ultraviolet absorber-containing polycarbonate resin (“Panlite 5250ZS” manufactured by Teijin Chemicals Ltd.) as an ultraviolet absorbing layer constituent resin and a polycarbonate resin (“Novalex 7027U” manufactured by Mitsubishi Engineering Plastics) as a transparent resin plate constituent resin , Each was put into a separate hopper, melted at a temperature of 280 ° C., then co-extruded using a multi-manifold die, and then the polycarbonate resin side of the UV absorbing layer was the mirror metal roll side, The surface is brought into contact with a metal roll previously engraved in a prismatic shape of a right triangle shape having an acute angle angle of 6.7 ° and an obtuse angle angle of 83.3 ° and a height of 0.33 mm, A prism surface was provided on the opposite surface and cooled and solidified to obtain a sheet.

The obtained sheet had a two-kind two-layer structure in which the total thickness was 2 mm and the thickness ratio of the ultraviolet absorbing layer / resin layer was 35/165.
Further, the formed prism surface has triangular prism-shaped unit prisms arranged in parallel in the width direction, and the angle α of the bottom acute angle portion of the unit prism is 6.7 °, The obtuse angle part β is 83.3 °, the top part of the unit prism is rounded, the radius of curvature is 0.3 mm, and the vertex interval (prism pitch) L between adjacent unit prisms is 3 mm. The height H of the unit prism was 0.29 μm.

<Example 2>
In Example 1, the opposite surface on the mirror metal roll side is preliminarily engraved into a prism shape having a triangular section with a height of 0.15 mm and an acute angle angle of 3 ° and an obtuse angle of 87 °. A sheet having a two-kind two-layer structure was obtained in the same manner as in Example 1 except that the sheet was brought into contact with the metal roll and a prism surface was provided on the opposite surface.

The obtained sheet had a two-kind two-layer structure in which the total thickness was 2 mm and the thickness ratio of the ultraviolet absorbing layer / resin layer was 35/165.
The formed prism surface has triangular prism-shaped unit prisms arranged in a row in the width direction, and the angle α of the bottom acute angle portion of the unit prism is 3 °, and the bottom obtuse angle portion The angle β of the unit prism is 87 °, the top of the unit prism is rounded, the radius of curvature is 0.2 mm, the apex distance (prism pitch) L between adjacent unit prisms is 3 mm, and the height of the unit prism is high. The height H was 0.14 mm.

<Example 3>
In Example 1, the opposite surface on the mirror metal roll side is previously engraved into a prism shape having a triangular section with a height of 0.43 mm and an acute angle angle of 9 ° and an obtuse angle of 81 °. A sheet having a two-kind two-layer structure was obtained in the same manner as in Example 1 except that the sheet was brought into contact with the metal roll and a prism surface was provided on the opposite surface.

The obtained sheet had a two-kind two-layer structure in which the total thickness was 2 mm and the thickness ratio of the ultraviolet absorbing layer / resin layer was 35/165.
The formed prism surface has triangular prism-shaped unit prisms arranged in a triangle in a continuous manner in the width direction, the angle α of the bottom acute angle part of the unit prism is 9 °, and the obtuse angle part of the bottom part The angle β of the unit prism is 81 °, the top of the unit prism is rounded, the radius of curvature is 0.2 mm, the apex distance (prism pitch) L between adjacent unit prisms is 3 mm, and the height of the unit prism is high. The height H was 0.38 mm.

<Comparative Example 1>
In Example 1, the opposite surface on the mirror metal roll side is engraved in advance into a prismatic shape of a right triangular shape having a base angle of 2 ° and an obtuse angle of 88 ° and a height of 0.1 mm. A sheet having a two-kind two-layer structure was obtained in the same manner as in Example 1 except that the sheet was brought into contact with the metal roll and a prism surface was provided on the opposite surface.

The obtained sheet had a two-kind two-layer structure in which the total thickness was 2 mm and the thickness ratio of the ultraviolet absorbing layer / resin layer was 35/165.
The formed prism surface has triangular prismatic unit prisms having a right-angled triangular cross section arranged continuously in the width direction, the angle α of the bottom acute angle portion of the unit prism is 2 °, and the obtuse bottom angle The angle β of the portion is 88 °, the top of the unit prism is rounded, the radius of curvature is 0.2 mm, the vertex interval (prism pitch) L between adjacent unit prisms is 3 mm, The height H was 0.1 mm.

<Comparative Example 2>
In Example 1, the opposite surface on the mirror metal roll side is engraved in advance into a prismatic shape of a right triangle having a base angle of 10 ° and an obtuse angle of 80 ° and a height of 0.48 mm. A sheet having a two-kind two-layer structure was obtained in the same manner as in Example 1 except that the sheet was brought into contact with the metal roll and a prism surface was provided on the opposite surface.

The obtained sheet had a two-kind two-layer structure in which the total thickness was 2 mm and the thickness ratio of the ultraviolet absorbing layer / resin layer was 35/165.
The formed prism surface has triangular prismatic unit prisms having a right-angled triangular cross section arranged continuously in the width direction, the angle α of the bottom acute angle portion of the unit prism is 10 °, and the obtuse bottom angle The angle β of the portion is 80 °, the top of the unit prism is rounded, the radius of curvature is 0.2 mm, the vertex interval (prism pitch) L between adjacent unit prisms is 3 mm, The height H was 0.42 mm.

<Comparative Example 3>
In Example 1, a sheet having no prism shape was produced.
That is, an ultraviolet absorbent-containing polycarbonate resin (“Panlite 5250ZS” manufactured by Teijin Kasei Co., Ltd.) as an ultraviolet absorbing layer constituting resin and a polycarbonate resin (“Novalex 7027U” produced by Mitsubishi Engineering Plastics) as a transparent resin plate constituting resin Were respectively fed into hoppers of separate extruders, both melted at a temperature of 280 ° C., then coextruded using a multi-manifold die, and then cooled and solidified by passing between two mirror surface metal rolls. Got.

[Testing and evaluation]
<Total light transmittance, haze>
Using HM-150 (Murakami Color Research Laboratory Co., Ltd.), the total light transmittance (JIS K 7361) and haze (JIS K 7136) of the sheets obtained in Examples and Comparative Examples were measured.
When the total light transmittance was 85% or more and the haze was 2% or less, “◯” was evaluated. Otherwise, “X” was evaluated, and the results are shown in Tables 1 and 2.

<Execution test>
(1) Refraction angle The sheets obtained in the examples and comparative examples have the prism surface facing away from the light incident side, the length direction of the unit prism on the prism surface is directed in the east-west direction, and the south The unit prisms 3a are arranged so that they are inclined so as to be inclined 10 ° higher, that is, the north side edge is inclined 10 ° higher than the south side edge, and the standing side is positioned above the inclined side in each unit prism 3a. That is, in other words, in each unit prism 3a, the sheet is inclined so that the bottom angle β side is located obliquely above the bottom angle α side. And assuming a summer south solstice altitude of 78 ° (Tokyo) and a winter solstice altitude of 31 ° (Tokyo), the light source from the south is 78 ° or 31 ° high and transparent weather resistance. Light was actually incident on the resin surface, and the angle refracted with respect to the incident angle was measured using CR-200 (Murakami Color Research Laboratory Co., Ltd.). The results are shown in Tables 1 and 2. .

(2) Illuminance The sheets obtained in Examples and Comparative Examples were installed as Tostem Power Alpha F type (between 6 and 2) terrace roofing materials. At this time, the prism surface is directed to the side opposite to the light incident side, and the length direction of the unit prism on the prism surface is directed to the east-west direction, and is further inclined to be 10 ° higher toward the south. That is, the north side edge is inclined so as to be 10 ° higher than the south side edge, and the upright side of each unit prism 3a is located at the upper part of the inclined side, that is, the bottom angle in each unit prism 3a. The sheet was installed so as to be inclined so that the β side is located obliquely above the bottom angle α side.
Terrace roofing material and front panel are constructed facing south, the room size (12 tatami mats between Chukyo), window part 1650mm x 1800mm, summer solstice (fine weather, temperature 30 ° C) or winter solstice (fine weather, temperature 13 ° C) 12 Measure the illuminance (lx) on the floor at 0m, 3.5m, 4.5m, 5.5m from the south side window to the north side when 1 hour has passed since 13:00. The results are shown in Tables 1 and 2.

<Simulation test>
Using simulation software, assuming that the sheets obtained in the above examples and comparative examples are used as a roofing material for terraces, simulation is performed under different conditions, and preferable ranges of the bottom angles α and β of the unit prism are set. investigated.

More specifically, using the lighting design analysis software (product name “Light Tools”), the sheets obtained in the above examples and comparative examples are terrace roofs having the dimensions shown in FIGS. 7A and 7B. The average illuminance and illuminance distribution were measured on the assumption that the material (roof material area: 6.9 m ² ) and the terrace front panel were used.
At this time, the room with the terrace (12 tatami mats between Chukyo) is divided into 20 squares in the north-south direction and 10 squares in the east-west direction, the illuminance of each square is measured, and the following formula (1 ) To calculate the average illuminance.
(1) .. Average illuminance = (average illuminance value of all cells) × 100 / (average illuminance value of all cells without the prism surface (Comparative Example 1))
Moreover, in the figure in the table | surface which shows illumination intensity distribution, the complete shadow was represented by black and the illumination intensity as it was sunlight was represented by white, and the illumination intensity distribution was shown.

  The sheets obtained in Examples 1 to 3 and Comparative Examples 1 to 3 have their prism surfaces facing away from the light incident side, the length direction of the unit prism on the prism surface is directed in the east-west direction, and Inclined to be 10 ° higher toward the south, that is, tilted so that the north side edge is 10 ° higher than the south side edge, and the bottom angle β side is the bottom angle α side in each unit prism 3a. Assuming that the seat is tilted so as to be located at a more diagonally upper position, the average illuminance and illuminance at the South-Medium Altitude (78 °) at the summer solstice in Tokyo and at the South-Medium Altitude (31 °) at the Winter Solstice in Tokyo. The distribution was simulated and the results are shown in Tables 1 and 2, and the preferred range of the top angle of the unit prism was examined.

(Discussion)
Looking at the results of Comparative Example 3, when using ordinary daylighting material that is not shaped, it can be confirmed that light is not shining from 3.5 m to 5.5 m from the room window in winter. It was. It can be easily imagined that the light hits only the window and there is less light as it goes into the back of the room, and a temperature difference occurs in the room. Therefore, it is considered that a comfortable living space can be achieved by eliminating light in the room at a position of 3.5 m to 5.5 m in a general living room of about 12 tatami mats to eliminate the temperature difference between the rooms.
On the other hand, in Examples 1, 2, and 3, light is guided in the range from 3.5 m to 5.5 m in the back of the room in winter without affecting the illuminance of the room. It could be confirmed.

In Experimental Example 3, the angle α was set to 9 °, so that the light was guided to the very edge of the wall at the back of the room at the summer solstice, and in the case of Comparative Example 2 in which the angle α was 10 °, 3.5 m to 5 As a result of the light hitting the wall at the back of the room over a distance of .5m, not only the improvement in daylighting to the position of 3.5m to 5.5m can be obtained, but the transmission angle becomes too large. You may feel dazzled. Therefore, it is considered that 9 ° is preferable as the upper limit angle of the bottom portion angle α at which light is collected at a position of 3.5 m to 5.5 m.
On the other hand, when the result of the comparative example 1 is seen, when the bottom angle α is 2 °, the refraction angle is not large, so that light cannot be guided to a position of 3.5 m to 5.5 m in the winter solstice. A sufficient light guiding effect is not obtained.
Therefore, the range of the bottom angle α is 3 ° in Example 2 to 9 ° in Example 3 because light can be guided into the back of the room in winter without affecting summer. It is possible to eliminate the temperature difference.

DESCRIPTION OF SYMBOLS 1 Light guide plate 2 Transparent resin plate 3 Prism surface 3a Unit prism 4 Ultraviolet absorption layer

Claims (4)

  At least one side of the transparent resin plate 2 is provided with a prism surface 3 having a configuration in which triangular prism-shaped unit prisms 3 a having a triangular cross section are continuously arranged in the width direction, and the unit prism constituting the prism surface 3 3. A light guide plate, wherein one bottom angle α of 3a is 3 ° or more and 9 ° or less, and the other bottom angle β is 60 ° or more and 90 ° or less.   The prism surface 3 is positioned on the side opposite to the light incident side, and the light guide plate is inclined so that the side of the bottom angle β is located obliquely above the side of the bottom angle α in each unit prism 3a. The light guide plate according to claim 1.   The light guide plate according to claim 1, wherein an ultraviolet absorbing layer 4 is provided on the upper surface side of the transparent resin plate 2.   The light guide plate according to any one of claims 1 to 3, wherein the light guide plate is used as a roofing material for a terrace and a fence, or as a surface material for a terrace front panel, a louver, a fence, and a balcony.

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