JP5514616B2 - Light guide plate - Google Patents

Description

  The present invention relates to a light guide plate suitable for use as a roofing material such as a terrace or a carport.

  Conventionally, roofing materials for terraces and carports are often made from weather-resisting transparent resin plates made of acrylic resin, polycarbonate resin, polyester resin, etc. from the viewpoint of lightness, transparency, impact resistance, etc. It has been. Transparent thermoplastic resins tend to absorb ultraviolet rays, so when exposed to sunlight for a long time, they will not only deteriorate due to ultraviolet rays, but also the ultraviolet rays contained in sunlight will penetrate the building materials, In order to prevent deterioration, discoloration, alteration, etc. of articles placed in the room or in the car, in order to suppress such adverse effects of ultraviolet rays, paint containing organic ultraviolet absorbers, titanium oxide or zinc oxide on its surface A resin plate formed by applying a blended paint to form an ultraviolet blocking coating has been used (see Patent Document 1).

  Roofing materials such as terraces and carports are required not only to protect against rain and snow, but also to have a function to prevent direct sunlight while ensuring brightness. For example, in the case of carport roofing materials, it is required to prevent sunlight in the vehicle during the summer and to encourage sunlight into the vehicle during the winter so that the interior can be brought to a comfortable temperature in a short time. .

  As a conventional roofing material, for example, Patent Document 2 discloses a plurality of right-angle prisms as a translucent panel that selectively transmits incident light in an incident angle region and reflects incident light in a region with a small incident angle. The thing of the structure formed by adjoining is disclosed.

  Further, in Patent Document 3, a heat insulating material is detachably attached to the lower surface of a transparent prism panel composed of a plurality of right-angle prisms having an action of reflecting incident light from the incident direction of sunlight in summer. There has been disclosed a daylighting roof in which a roof surface is formed by disposing. Patent Document 3 also exemplifies, as the right-angle prism, a linear prism having a right-angled isosceles triangle section or a cubic prism having a shape (pyramid shape) like the top of a cube.

JP 2000-63647 A Claim 1 of JP-A-58-189441 Claim 1 etc. of Japanese Patent Laid-Open No. 62-148757

In roofing materials such as carports, by controlling the emission angle of the sunlight that has passed through the roofing material, in summer, the illuminance in the lower part can be suppressed and the temperature rise in the vehicle due to sunlight can be suppressed. In winter, it is required that the illuminance at the lower part can be increased to increase the temperature inside the vehicle, but a roof material having such a function has not been disclosed.
In addition, in the case of a roof material such as a carport, it is necessary to assume a case where snow or the like is piled up. Therefore, load durability having a property of bending due to a load such as snow is required.

  Therefore, the present invention can control the illuminance of the lower part in summer by controlling the emission angle of incident light, and can increase the illuminance on the contrary in winter, and has excellent load durability. It is intended to provide a light guide plate.

  The present invention has a configuration in which virtual pentahedral concave portions (each concave portion is referred to as a “unit prism concave portion”) in which a cross section in at least one direction has a virtual triangular shape are provided in parallel on the lower surface side of the transparent resin plate. A light guide plate having a prism surface is proposed.

If it is a light guide plate having such a configuration, for example, by using it as a roofing material such as a carport, the illuminance of the lower part can be suppressed in summer, and conversely, the illuminance can be increased in winter. The emission angle of sunlight can be controlled. Therefore, in the summer, when the sun is at the south and the altitude is the highest, sunlight rays incident at this angle are reflected on the prism surface so that the sunlight rays are not transmitted below the light guide plate. it can. On the other hand, when the angle of the sun is gradually lowered, the sunlight rays are transmitted to the lower side of the light guide plate, and in winter, when the sun angle is the lowest, the amount of sunlight transmitted to the lower side of the light guide plate is sufficient. It is possible to increase the temperature inside the vehicle by taking light into the parked vehicle.
Furthermore, in the case of a light guide plate having a configuration in which unit prism concave portions are arranged side by side as in the present invention, in other words, a waffle-shaped prism surface, a plurality of grooves having a triangular cross section are formed in a certain direction. Compared to the regular prism surface provided, not only can the illuminance in winter be further increased, but the illuminance in winter can be increased regardless of the direction of installation, and the load durability such as tensile strength and elongation characteristics can be improved. It has the feature of being excellent. Further, for example, compared to a light guide plate having a prism surface formed by juxtaposing pyramidal protrusions on the lower surface side of the resin plate, the volume of the prism portion is large, so the amount of refraction is large, for example, in winter and solar When the angle becomes the lowest, the amount of sunlight transmitted to the lower side of the light guide plate can be further increased.
Thus, the light guide plate of the present invention can be suitably used as various roofing materials such as carports and other terraces, daylighting materials for house openings, and other daylighting materials.

It is the fragmentary sectional perspective view which showed an example of the light-guide plate of this invention. It is the fragmentary sectional perspective view which showed the other example of the light-guide plate of this invention. FIG. 2 is an enlarged view showing the unit prism concave portion shown in FIG. 1 reversed upside down, where (A) is a perspective view, (B) is a BB cross-sectional view, and (C) is a CC cross-sectional view. FIG. 3 is an enlarged view showing the unit prism concave portion shown in FIG. 2 with the top and bottom reversed, wherein (A) is a perspective view, (B) is a BB sectional view, and (C) is a CC sectional view. 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 the side view which showed the modification of the light-guide plate of this invention. It is the figure which showed the light-guide plate produced as a comparative example with respect to this invention, (A) is the top view, (B) is the BB sectional drawing, (C) is the CC sectional drawing. It is the figure which showed the light-guide plate produced as Example 7-9 of this invention, (A) (C) and (E) are each a top view of Example 7-9, (B) is B of Example 7. -B sectional view, (D) is a DD sectional view of Example 8, (F) is a FF sectional view of Example 9, and (G) is a GG sectional view of Example 7-9. It is. It is the figure which showed the dimension etc. of the roof material of the carport assumed in the simulation test of an Example. It is the graph which showed the result of the test 1 in the summer about Example 3 (waffle) and the comparative example 1 (prism), ie, the relationship between the installation azimuth angle and illuminance in the summer. It is the graph which showed the result of the test 1 in the winter about Example 3 (waffle) and the comparative example 1 (prism), ie, the relationship between the installation azimuth angle and illumination intensity in the winter. It is the graph which showed the relationship between the pitch of a unit prism recessed part, and the maximum point stress (Mpa) about the result of the test 3, ie, Example 7-9, and a comparative example. It is the graph which showed the result of the test 3, ie, Example 7-9, and the comparative example, and the relationship between the pitch of a unit prism recessed part, and a fracture | rupture point strain (%).

  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>
As shown in FIGS. 1 and 2, 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 ultraviolet light on the upper surface side of the transparent resin plate 2. 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. Specific examples include polycarbonate resins produced from 2,2-bis (4-hydroxyphenyl) propane (bisphenol A), but are 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 the copolymerizable monomer 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. For example, polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-butene copolymer, ethylene-4-methyl-1-pentene copolymer, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, etc. 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. When 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 2 has a heat stabilizer, an ultraviolet absorber, a colorant, a fluorescent brightener, a release agent, an antiblocking agent (silica, crosslinked polystyrene beads, etc.), as long as the effects of the present invention are not impaired. You may contain additives, such as a softening material and an antistatic agent.

  The transparent resin plate 2 may have a flat plate shape as shown in FIG. 1 and FIG. 2 or the like, or may be a plate body that bulges upward as shown in FIG.

(Prism surface 3)
As shown in FIGS. 1 and 2, 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 the cross section in at least one direction is a virtual triangular shape. In other words, it has a configuration in which concave portions 3a each having a virtual pentahedron shape (where each concave portion is referred to as a “unit prism concave portion 3a”) are arranged in parallel, in other words, having a prism surface formed in a waffle shape.

  As shown in FIGS. 3 to 4, the unit prism recess 3a may have a virtual pentahedron shape in which a cross section in at least one direction, that is, a cross section in one or both of the vertical direction and the horizontal direction has a virtual triangular shape. That's fine. In this case, the “virtual triangle shape” and the “virtual isosceles triangle shape” mean that when the base is virtual, the triangle shape or the isosceles triangle shape is exhibited, and the “virtual pentahedron shape” means the bottom surface. It means that it has a pentahedral shape when virtual.

If the light guide plate has a prism surface 3 having a configuration in which such unit prism recesses 3a are arranged side by side on the lower surface side of the transparent resin plate 2, for example, as shown in FIG. Compared to a light guide plate with a regular prism surface with grooves in a certain direction, it can not only increase the illuminance in winter, but also increase the illuminance regardless of the installation direction, Excellent load durability such as tensile strength and elongation characteristics.
Also, compared to a light guide plate with a prism surface formed by arranging pyramid-shaped convex portions in parallel, the volume of the prism portion is large, so the amount of refraction is large, for example, in winter, when the sun angle is the lowest, It is excellent in that the amount of sunlight transmitted to the lower side of the light guide plate can be further increased and the illuminance can be increased.

The shape of the unit prism concave portion 3a may be a virtual quadrangular pyramid-shaped concave portion having a triangular shape in the vertical or horizontal direction as shown in FIG. 3, or as shown in FIG. The cross section of a horizontal direction may exhibit a virtual triangle shape, and the concave groove which exhibits a virtual pentahedron shape long in one direction may be sufficient.
Among them, those in which the cross section in the vertical direction or the horizontal direction exhibits a virtual isosceles triangle shape are preferable, and among them, those in which all the side surfaces exhibit a virtual pentahedron shape that is an inclined surface are preferable, most preferably a virtual quadrangular pyramid shape. It is a recessed part to be exhibited.

  In the unit prism recess 3a, the apex angle α (which is also the constriction angle) in a triangular cross section, in other words, the apex angle α of the ridge that is the boundary between the adjacent unit prism recesses 3a and 3a is: When the light guide plate 1 is used as a roofing material, it is preferably 60 ° or more and less than 120 ° from the viewpoint that the illuminance can be further suppressed in summer and the illuminance can be further increased in winter. More preferably, it is 100 ° or less, and more preferably 75 ° or more or 85 ° or less.

  As shown in FIGS. 3 and 4, the top of the ridge that is the boundary between adjacent unit prism recesses 3 a and 3 a may be rounded, but when this top is rounded, each of the ridges forming the ridge Since the area of the slope is reduced and the refractive power is reduced, the curvature radius R of the top is preferably greater than 0 mm and not greater than 0.5 mm. 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.

  The size of the unit prism recess 3a in plan view does not affect the optical characteristics. However, if it is made smaller, the depth of the unit prism recess 3a becomes relatively shallow and the durability is increased. Therefore, the smaller one is preferable in terms of durability.

Further, as shown in FIGS. 1 and 8E, the width (pitch) of the opening of the unit prism recess 3a may be the same in the vertical direction and the horizontal direction, or in FIGS. As shown in A) and (C), they may be different.
At this time, the ratio of the X pitch (Lx) in one direction (for example, the horizontal direction) and the Y pitch (Ly) in the other direction (for example, the vertical direction) is preferably 1: 1 to 1: 3, and most preferably. Is 1: 1.
Further, the pitch (Lx and Ly) of the unit prism recesses 3a is preferably 0.5 mm to 3 mm. As described above, since the depth of the unit prism recess 3a is relatively shallow, a smaller pitch is preferable in terms of durability. However, if the pitch is less than 0.5 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 pitch exceeds 3 mm, the groove between the unit prism recesses 3a and 3a becomes deep, and the strength of the light guide plate is lowered.
Therefore, the pitch (Lx and Ly) of the unit prism recesses 3a is particularly preferably 0.6 mm to 1.5 mm, and particularly preferably 0.6 mm to 1.2 mm.

The recess depth H of the unit prism recess 3a is determined by the apex angle of the unit prism recess 3a and the prism pitch, and is preferably 0.2 mm to 1.5 mm, and more preferably 0.2 mm to 1.5 mm. The thickness is preferably 1.0 mm, and more preferably 0.2 mm to 0.7 mm.
Since the thickness of the transparent resin plate 2 and the depth of the unit prism recess 3a affect the durability, the relationship between them, that is, the ratio of the depth of the unit prism recess 3a to the plate thickness of the transparent resin plate 2 is 90. : 100 to 1: 100, particularly 50: 100 to 3: 100, and particularly preferably 30: 100 to 3: 100.

(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.

  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.

<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, followed by surface finishing and cooling 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 being processed into a roof material such as a carport. If the prism surface 3 of the light guide plate 1 is disposed on the side opposite to the light incident side, the illuminance can be suppressed in the summer, while the illuminance can be increased in the winter. The emission angle can be controlled. Therefore, for example, when used as a roofing material for a carport, in summer, the temperature rise in the vehicle can be suppressed by sunlight, and conversely, in winter, the temperature inside the vehicle can be increased by taking light into the vehicle. .
In addition, the light guide plate 1 is characterized in that it is not restricted in the installation direction.
The light guide plate 1 having such an effect can be suitably used as a roofing material for a terrace or other daylighting materials in addition to a roofing material for a carport.

<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.

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

(Comparative Example 1)
An ultraviolet absorber-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, Each was put into a separate hopper and melted at a temperature of 280 ° C., and 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 and the opposite side Was brought into contact with a metal roll previously engraved into an isosceles triangle having an apex angle of 75 ° and a prism shape with a height of 508 μm, and a prism surface was provided on the opposite surface to cool and solidify.

The obtained sheet had a two-type two-layer configuration in which the total thickness was 2.5 mm and the thickness ratio of the ultraviolet absorbing layer / transparent resin layer was 40/2460.
As shown in FIG. 7, the formed prism surface has a width of a prism surface in which a plurality of grooves having an isosceles triangle cross section are provided in a certain direction, in other words, a triangular prism unit prism having an isosceles triangle cross section. It is a prism surface arranged side by side continuously in the direction, the apex angle of each unit prism is 75 °, the apex of any unit prism is rounded, the radius of curvature is 0.2 mm, and adjacent The vertex interval (prism pitch) between the unit prisms to be performed was 1.0 mm. The height of the unit prism was 510 μm.

(Example 1-6)
An ultraviolet absorber-containing polycarbonate resin (“Penlite 5250ZS” manufactured by Teijin Kasei Co., 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 and melted at a temperature of 280 ° C., and 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 and the opposite side Was brought into contact with a metal roll engraved so as to have a plurality of triangular mountain-shaped convex portions arranged side by side, and a prism surface was provided on the opposite surface to cool and solidify to obtain a light guide plate (sample).

The obtained light guide plate (sample) had a two-type two-layer configuration in which the total thickness was 2.5 mm and the thickness ratio of the ultraviolet absorbing layer / transparent resin layer was 40/2460.
Further, the formed prism surface is a waffle-shaped prism in which unit prism concave portions 3a each having a virtual quadrangular pyramid shape are continuously arranged side by side vertically and horizontally as shown in FIGS. 8 (E), (F), and (G). The dimensions of each unit prism recess 3a were as follows.
Top angle α: 55 °, 60 °, 75 °, 115 °, 120 °, 130 °
Roundness (R) at the top of the unit prism recess 3a: 0.2 mm
Pitch: Lx: 0.87 to 1.06 mm, Ly: 0.87 to 1.06 mm
Depth H of unit prism recess 3a: 0.22 to 0.78 mm

(Example 7-9)
Similarly to the above, a light guide plate (sample) was obtained by changing the pitch.
The obtained light guide plate (sample) had a two-type two-layer configuration in which the total thickness was 2.5 mm and the thickness ratio of the ultraviolet absorbing layer / transparent resin layer was 40/2460.
Further, as shown in FIGS. 8A to 8G, the formed prism surface has a virtual pentahedron shape in which at least a longitudinal section has a virtual isosceles triangle shape and all side surfaces are inclined surfaces. The unit prism recesses 3a are waffle-shaped prism surfaces arranged side by side continuously in the vertical and horizontal directions, and the dimensions of each unit prism recess 3a are as follows.
Top angle α: 75 °
Roundness (R) at the top of the unit prism recess 3a: 0.2 mm
Pitch: Lx: 1.0mm
Ly: 1.0 mm to 3.0 mm
Depth H of unit prism recess 3a: 0.51 mm

<Test 1: Examination of relationship between installation azimuth angle and illuminance>
A light guide plate (Example 3) provided with a waffle-shaped prism surface formed by juxtaposing virtual pentahedron-shaped unit prism concave portions having a triangular cross section in at least one direction on the lower surface side of the transparent resin plate; Assuming the case where a light guide plate (Comparative Example 1) provided with a regular prism surface on the lower surface side of a transparent resin plate is used for a carport roofing material. The illuminance when changing the azimuth angle was examined by simulation.
In addition, in the simulation of Test 1 and Test 2, the roundness (R) of the top cannot be set. Therefore, the light guide plates (samples) of the practical examples and the comparative examples that were actually manufactured were measured at the top of the unit prism recess 3a. The roundness (R) is set to 0 mm (the recess depth (H) and pitch (Lx and Ly) are changed accordingly), and other data is set as in the light guide plate (sample) of the example and the comparative example. did. Even if the roundness of the top (R), the depth of the recess (H), and the pitch (Lx and Ly) are changed, the relationship between the installation azimuth angle and the illuminance, and the angle of the top of the unit prism recess 3a and the illuminance The relationship is not affected.

(Simulation test)
Simulation was performed on the assumption that the light guide plate (sample) was used as a carport roofing material using simulation software.

Specifically, using lighting design analysis software (product name “Light Tools”), the seats obtained in the above-mentioned examples and comparative examples are converted into carport roofs having the dimensions shown in FIGS. 9A and 9B. material (L1 = 4980mm, L2 = 2406 , H1 = 2357mm, H2 = 1796mm, R1 = 99 °, roofing area = 12m ²⁾ and processed into intended for use to measure the average illuminance.
At this time, the range immediately below the carport (also referred to as the “effective range”) is divided into 20 squares in the north-south direction and 10 squares in the east-west direction, and further, the measurement range is 2 squares each in the east-west-north-south direction. , Measure the illuminance of each mass, and target all the masses to the resin plate that does not form a prism surface in Example 1 (; blank, thickness 2.5 mm, UV absorbing layer / transparent resin layer thickness ratio The ratio (%) of the average illuminance of the sample to the average illuminance of 40/2460) was calculated by the following equation (1).
(1) .. Average illuminance (%) = (Average illuminance value of all cells) × 100 / (Average illuminance value of all blank cells)

  At this time, assuming that the length direction is 0 ° in the north-south direction and changing the direction in increments of 30 °, the south-middle altitude at the summer solstice in Tokyo (78 °) and the south-middle altitude in the winter solstice in Tokyo as well. The average illuminance at (31 °) was calculated and shown in Table 2 and FIGS.

(Discussion)
When comparing a normal prism surface (Comparative Example 1) having grooves arranged in a certain direction and a prism surface having unit prism recesses arranged in parallel, in other words, a waffle-shaped prism surface (Example 3), Particularly in winter, in the case of a normal prism surface (Comparative Example 1), the illuminance ratio (%) with respect to a plate (blank) that does not form a prism is 60 °, 90 °, 120 °, 240 °, 270 °, In the case of 300 °, the illuminance cannot be increased, that is, the light guide effect in winter is not expressed, whereas in the case of the waffle-shaped prism surface (Example 3), It was confirmed that the light guide effect was exhibited in the direction. Therefore, when a light guide plate having a prism surface formed by arranging unit prism recesses in parallel, in other words, a waffle-shaped prism surface, is used as a roofing material for a carport, the installation angle can be made arbitrary. .

<Test 2: Relationship between the angle of the top of the unit prism recess 3a and illuminance>
Assuming that light guide plates (samples) with various top angles were used for carport roofing materials, the relationship between the top angle and illuminance was examined by simulation.

(Simulation test)
A simulation was performed on the assumption that the light guide plate (sample) was used as a carport roofing material using simulation software, and a preferable range of the top angle of the unit prism recess 3a was examined.

Specifically, using lighting design analysis software (product name “Light Tools”), the seats obtained in the above-mentioned examples and comparative examples are converted into carport roofs having the dimensions shown in FIGS. 9A and 9B. material (L1 = 4980mm, L2 = 2406 , H1 = 2357mm, H2 = 1796mm, R1 = 99 °, roofing area = 12m ²⁾ and processed into intended for use to measure the average illuminance.
At this time, the range immediately below the carport (also referred to as the “effective range”) is divided into 20 squares in the north-south direction and 10 squares in the east-west direction, and further, the measurement range is 2 squares each in the east-west-north-south direction. , Measure the illuminance of each mass, and target all the masses to the resin plate that does not form a prism surface in Example 1 (; blank, thickness 2.5 mm, UV absorbing layer / transparent resin layer thickness ratio The ratio (%) of the average illuminance of the sample to the average illuminance of 40/2460) was calculated by the following equation (1).
(1) .. Average illuminance (%) = (Average illuminance value of all cells) × 100 / (Average illuminance value of all blank cells)

  At that time, assuming that the length direction is 0 ° from the north-south direction, the south-middle altitude at the summer solstice in Tokyo (78 °) and the south-middle altitude at the winter solstice in Tokyo (31 °) The average illuminance at the time was calculated, and the results are shown in Table 3.

(Discussion)
From the viewpoint that the illuminance can be further suppressed in summer and the illuminance can be further increased in winter, the apex angle α is preferably 60 ° or more and less than 120 °, particularly 70 ° or more or 100 ° or less. It was more preferable that it was more preferably 75 ° or more or 85 ° or less.

<Test 3: Relation between pitch of unit prism recess 3a and load durability>
About the light guide plate (sample) of Example 7-9 in which the pitch of the unit prism recesses 3a was changed, a tensile test was performed under the following measurement conditions in accordance with JIS K 7162, and the maximum point stress (Mpa) and the strain at break (%) ) Were measured, and the relationship between these and the pitch was shown in FIGS. 12 and 13, and a suitable pitch range was examined.

Measuring device: “AG-20kNG” manufactured by Shimadzu Corporation
Load cell: SFL-20KNAG
Sample shape: Dumbbell type Test piece 1B type

(Discussion)
From the results of FIGS. 12 and 13, the ratio of the X pitch (Lx) in one direction (for example, the horizontal direction) and the Y pitch (Ly) in the other direction (for example, the vertical direction) is the maximum point stress (Mpa) and the fracture. It turned out that it is so preferable that it is close to 1: 1 in any point strain (%).
Therefore, when this result and the test results conducted so far are combined, the ratio between the X pitch (Lx) in one direction (for example, the horizontal direction) and the Y pitch (Ly) in the other direction (for example, the vertical direction) is 1 Is preferably 1: 1 to 1: 3, more preferably 1: 1 to 1: 2, and most preferably 1: 1.
Further, regarding the absolute value of the pitch (Lx and Ly) of the unit prism recesses 3a, the depth of the unit prism recesses 3a is relatively shallow. Therefore, the smaller pitch is preferable in terms of durability, but the pitch is small. If it is too much, the ratio of the curved part (R part) increases, so that the light guide performance may be lowered, and the mold is manufactured as the pitch of the mold for shaping the prism increases. From this point of view, the pitch (Lx and Ly) of the unit prism recesses 3a is preferably about 0.5 mm to 3 mm, particularly 0.6 mm. It can be considered that it is more preferable that it is -1.5 mm, and especially it is 0.6 mm-1.2 mm among them.

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

Claims (6)

On the lower surface side of the transparent resin plate, at least cross-section in one direction in the light guide plate having a prism surface having a structure formed by parallel virtual pentahedron like recess ( "unit prisms recesses") exhibiting a virtual triangular A light guide plate characterized by being used as a roofing material.   The light guide plate according to claim 1, wherein the unit prism recess has a virtual quadrangular pyramid shape.   3. The light guide plate according to claim 1, wherein the radius of curvature of the top of the unit prism recess is greater than 0 mm and equal to or less than 0.5 mm.   The light guide plate according to any one of claims 1 to 3, wherein the light guide plate is used so that the prism surface is positioned on the side opposite to the light incident side.   The light guide plate according to claim 1, further comprising an ultraviolet absorbing layer on an upper surface side of the transparent resin plate.   It uses as a roof material of a carport, The light-guide plate in any one of Claims 1-5 characterized by the above-mentioned.

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