JP2011009548A - Reflection protection sheet and semiconductor power generator using same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reflection protection sheet and a semiconductor power generator capable of manufacturing products of fixed quality without deformation arising when assembling, while capable of raising power generation efficiency.SOLUTION: This reflection protection sheet 10 comprises: a transmissive protective layer 17 that lets light emitted from the back surface of the semiconductor power generator body transmit, a reflective structure layer 16 disposed on the back surface side of the transmissive protective layer 17 that reflects the light transmitted through the transmissive protective layer 17 toward the transmissive protective layer 17, and an outer layer 11 disposed on the back surface side of the reflective structure layer 16 that protects the reflective structure layer 16. The reflective structure layer 16 is composed of an optical structure layer 15 that has formed a concavo-convex shape on the front surface or back surface, and a reflection film 14 laminated on the concavo-convex shape. The optical structure layer 15 is formed of thermosetting resin, or thermoplastic resin of no lower than 95°C in vicat softening temperature.

Description

  The present invention provides a reflection protective sheet capable of reusing light originally lost by deflecting light in a specific direction by light diffraction, scattering, diffusion, refraction, or reflection action, and The present invention relates to a semiconductor power generation device using a reflection protection sheet.

  While interest in global warming is increasing, various efforts are being made to reduce carbon dioxide emissions. Increased consumption of fossil fuels will lead to an increase in atmospheric carbon dioxide, and the greenhouse effect will raise the temperature of the earth and have a significant impact on the global environment. As an alternative to fossil fuels, there is an increasing expectation for power generation using sunlight, which has a low environmental burden among various natural energies.

A semiconductor power generation device used for power generation by sunlight uses a semiconductor having a pn junction as a photoelectric conversion unit that directly converts light energy into electricity, and silicon is generally the most common semiconductor constituting the pn junction. It is often used. The above-described silicon used in such a semiconductor power generation device is classified into a crystalline type and an amorphous type.
Moreover, on the said photoelectric conversion part, generally glass substrates, such as transparent tempered glass, are provided as a sealing base material which protects a photoelectric conversion part from air and an impurity.

  Hereinafter, a package in which at least one cell including the photoelectric conversion unit is sealed with a sealing material and packaged is referred to as a semiconductor power generation device.

This semiconductor power generator is configured by connecting small-sized cells by a plurality of electrodes. In the case of a silicon crystal-based semiconductor power generation device, a plurality of cells are arranged at intervals, and a certain amount of gap is formed between adjacent cells. Further, a marginal portion where no cell is arranged is provided in the range of several millimeters to several tens of millimeters at the end of the semiconductor power generation device in order to prevent erosion such as rainwater.
Since there are no cells in these gaps and blank portions, even if light is applied to these regions, it does not contribute to power generation, leading to light loss.

  Therefore, conventionally, in order to improve the loss of light poured into the gaps and margins of the cells as described above, in the crystalline semiconductor power generation device, the reflection protection sheet disposed on the back surface is used as a light reflecting material, and the light is again transmitted to the cell side. Then, a method is employed in which the total reflection is performed by a glass plate as a front plate and the incidence is reincident on the light receiving surface of the cell to increase efficiency.

In addition, a structure has been proposed in which a concavo-convex structure is provided on the reflective protective sheet on the back surface, and the light reflected on the concavo-convex structure is easily scattered to improve the probability of guiding it to the light receiving surface of the cell, thereby increasing the light utilization efficiency. (For example, see Patent Documents 1 and 2).
Further, a configuration has been proposed in which light is scattered by making the reflection protection sheet on the back surface uneven, and efficiency is improved by using a cell in which both surfaces of the cell are light receiving surfaces (see, for example, Patent Document 3).

Japanese Utility Model Publication No. 62-101247 Japanese Patent Laid-Open No. 10-284747 Japanese Patent No. 3670835

  By the way, the semiconductor power generation apparatus as described above is required to realize higher power generation efficiency as a technique for simultaneously solving the energy problem and the environmental problem. The inventors of the present invention can realize a higher power generation efficiency by specifying the shape of the concavo-convex structure to be applied to the reflection protection sheet and further forming a reflective film on the concavo-convex structure. I found However, there is a problem that high heat generation efficiency cannot be stably supplied due to deformation in the shape of the concavo-convex structure due to heat applied in the assembly process.

  The present invention has been made in view of such problems, and it is possible to improve power generation efficiency, and to provide a reflection protective sheet and a semiconductor power generation capable of maintaining a certain quality without causing deformation during assembly. An object is to provide an apparatus.

In order to solve the above problems, the present invention proposes the following means.
That is, the reflection protection sheet according to the present invention is a reflection protection sheet disposed on the back side of a semiconductor power generation device body that generates light by receiving light from the front surface, and at least passes through the semiconductor power generation device. A transmissive protective layer that transmits light emitted from the back surface of the power generation device, and a reflection that is disposed on the back surface side of the transmissive protective layer and reflects light transmitted through the transmissive protective layer toward the front surface side A structural layer; and an outer layer disposed on the back side of the reflective structural layer to protect the reflective structural layer, wherein the reflective structural layer is formed with a concave or convex shape on the front or back surface, and the concave and convex The optical structure layer is made of a thermosetting resin or a thermoplastic resin having a Vicat softening temperature of 95 ° C. or higher.

According to the reflection protective sheet having such a feature, it is possible to reflect light with high efficiency toward the front surface side by forming the reflection structure layer by laminating the reflection film on the uneven shape of the optical structure layer. By making this reflected light enter from the back side of the semiconductor power generator main body, it is possible to improve the power generation efficiency. In addition, since the material for forming the optical structure layer is a thermosetting resin or a thermoplastic resin having a Vicat softening temperature of 95 ° C. or higher, the optical structure layer is deformed when assembling a semiconductor power generation device equipped with the reflection protection sheet. There is little and can maintain a certain quality.
The Vicat softening temperature is measured by the B50 method in JIS-K7206.

Further, in the reflection protective sheet according to the present invention, the concavo-convex shape is formed on the front surface of the optical structure layer, and between the reflective film and the transmissive protective layer laminated in the concavo-convex shape, water vapor transmission is performed. A barrier layer having a degree of 0 to 0.5 g / m ² is provided.

By forming the barrier layer, it is possible to prevent the permeation of water vapor into the semiconductor power generator main body, and to prevent the corrosion of the electrodes used in the semiconductor power generator main body and the deterioration of the sealing resin.
Note that if the water vapor permeability exceeds 0.5 g / m ² , corrosion of the electrode or deterioration of the sealing resin may occur, which is not desirable. In this respect, by setting the water vapor transmission density within the above range, corrosion of the electrode and deterioration of the sealing resin can be surely avoided.
In addition, by disposing the barrier layer between the transmissive protective layer and the reflective film, it is possible to suppress the deterioration of the reflective film due to acetic acid generated by crosslinking of the filling layer.

  In the reflection protective sheet according to the present invention, the uneven shape is formed on the back surface of the optical structure layer, and the reflective film and the outer layer are laminated in an uneven shape between the reflective film and the outer layer. And a barrier layer having a water vapor permeability of 0 to 0.5 g / m 2.

By forming the barrier layer, it is possible to prevent water vapor from penetrating into the semiconductor power generation device main body, and to prevent corrosion of electrodes used in the semiconductor power generation device and deterioration of the sealing resin.
Note that if the water vapor permeability exceeds 0.5 g / m ² , corrosion of the electrode or deterioration of the sealing resin may occur, which is not desirable. In this respect, by setting the water vapor transmission density within the above range, corrosion of the electrode and deterioration of the sealing resin can be surely avoided.
In addition, by disposing the barrier layer between the reflective structure layer and the outer layer, oxidation of the reflective film due to water vapor or oxygen from the outer layer can be suppressed.

Furthermore, the reflection protective sheet according to the present invention is characterized in that the barrier layer comprises an inorganic oxide.
Thereby, oxygen barrier property and water vapor | steam barrier property can be improved, and also it becomes possible to improve heat resistance.

  Further, in the reflection protection sheet according to the present invention, the uneven shape is a faceted shape, a conical shape, a shape in which the top of the facet shape is rounded, a shape in which the top of the conical shape is rounded, or these shapes It is one of the reverse types.

By making the uneven shape into a prism shape such as a facet shape or a conical shape, the reflectance can be improved. On the other hand, when the concavo-convex shape is an aspherical lens having a high aspect ratio, the reflectance decreases due to the influence of scattering and absorption, which is not preferable.
In addition, the shape with rounded facet-shaped tops and the shape with rounded conical-shaped tops prevent scratches on the uneven shape during the manufacturing process while maintaining good reflectivity. Can do.

  Furthermore, the reflection protective sheet according to the present invention is characterized in that an apex angle of the concavo-convex shape is set in a range of 111 ° to 137 °.

In the reflection protective sheet having such a feature, when the refractive index of the sealing resin and glass used in the semiconductor power generation device main body is set to about 1.5 by setting the angle of the apex angle to the above angle range. It is possible to prevent total reflection at the interface between the glass and air and the incidence of the reflected light on the reflective structure layer.
On the other hand, when the apex angle exceeds 137 °, total reflection is less likely to occur at the interface between the glass and air, so that the possibility of recondensing efficiency is increased, which is not preferable. In addition, when the apex angle is less than 111 °, there is a high possibility that a part of the light reflected by the reflective structure layer collides with the reflective structure layer, and the re-condensing efficiency is lowered.

  In the reflection protective sheet according to the present invention, it is desirable that the apex angle of the concavo-convex shape is set in a range of 120 ° to 135 °.

In the reflection protective sheet having such a feature, the refractive index of the sealing resin and glass used in the semiconductor power generation device is set to about 1.5, as described above, by setting the angle of the apex angle to the above angle range. In this case, it is possible to prevent the total reflection at the interface between the glass and air and the reflected light from entering the light reflection uneven portion.
On the other hand, if it is attempted to mold the apex angle to an angle exceeding 135 °, it is difficult to always form the angle within a range where the total reflection at the interface between glass and air is difficult. On the other hand, when the angle is less than 120 °, a part of the light reflected by the reflecting structure collides in the light reflection uneven portion, and the reflectivity slightly decreases.

  A semiconductor power generation device according to the present invention includes a front plate that receives light, a filling layer that transmits light transmitted through the front plate, and a light that is sealed inside the filling layer and that is transmitted through the filling layer. One of the above-mentioned reflection protective sheets is laminated on the back side of a semiconductor power generation device main body provided with a cell that receives light from the light receiving surface and converts it into electricity.

  In the semiconductor power generation device having such characteristics, the power generation efficiency can be improved by arranging any one of the above-described reflection protection sheets on the back side of the semiconductor power generation device body to constitute the semiconductor power generation device. Therefore, it is possible to realize a semiconductor power generation device of a certain quality that does not deform when assembled.

  According to the reflection protective sheet and the semiconductor power generation device of the present invention, it is possible to improve the power generation efficiency by forming the reflection structure layer by laminating the reflection film on the uneven shape of the optical structure layer. In addition, since the material for forming the optical structure layer is a thermosetting resin or a thermoplastic resin having a Vicat softening temperature of 95 ° C. or higher, the optical structure layer is deformed when assembling a semiconductor power generator equipped with the reflection protection sheet. Therefore, a certain quality can be maintained.

It is a longitudinal section showing a schematic structure of a semiconductor power generator of an embodiment. It is a longitudinal cross-sectional view which shows schematic structure of the reflection protection sheet of 1st Embodiment. It is a perspective view which shows an example of the uneven | corrugated shape of an optical structure layer. It is sectional drawing which shows the angle of the top part of the uneven | corrugated shape of an optical structure layer. It is a longitudinal cross-sectional view which shows schematic structure of the reflection protection sheet of 2nd Embodiment. It is a longitudinal cross-sectional view which shows schematic structure of the reflective protection sheet of 3rd Embodiment. It is explanatory drawing of the measuring method of the re-condensing efficiency in an Example.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a reflection protection sheet and a semiconductor power generator according to the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a longitudinal sectional view showing a schematic configuration of a semiconductor power generator according to an embodiment. As shown in FIG. 1, the semiconductor power generation device 100 is configured by laminating a reflection protection sheet 10 on the back side of the semiconductor power generation device main body 1.

  The semiconductor power generation device main body 1 is composed of a front plate 2, a filling layer 3, and a cell 4, and is a device that generates power by receiving light rays. In addition, as a light ray, the light of artificial lighting, such as sunlight and an interior lamp, is normally employ | adopted.

  The front plate 2 is disposed on the forefront of the semiconductor power generator main body 1 so that light rays are directly incident on the surface. The front plate 2 is made of a transparent material having a high light transmittance. Specifically, a resin sheet such as tempered glass or PEN (polyethylene naphthalate) is used. The thickness of the front plate 2 is set to about 5 mm for tempered glass and several tens to several hundreds μm for a resin sheet.

  The light incident on the front plate 2 enters the filling layer 3. The filling layer 3 is laminated on the back side of the front plate 2 and has a role of sealing the cells 4. The filling layer 3 is made of a material having a high light transmittance in order to transmit light incident from the front plate 2 and is made of, for example, EVA (ethylene vinyl acetate) having flame retardancy.

  The light transmitted through the filling layer 3 enters the cell 4. A plurality of the cells 4 are embedded in the filling layer 3 and have a function of converting light incident on the light receiving portion into electric power by the photoelectric effect. As the cell 4, a single crystal silicon type, a polycrystalline silicon type, a thin film silicon type, a CIGS (Cu · In · Ga · Se compound) type thin film type or the like is used. The plurality of cells 4 are connected to each other by electrodes (not shown), and the electric power generated by the electrodes is taken out to the outside.

The light transmitted through the filling layer 3 and the cell 4 enters the reflection protection sheet 10 disposed on the back surface of the semiconductor power generator main body 1. The reflection protection sheet 10 has a function of reflecting incident light to the semiconductor power generator main body 1.
The light reflected by the reflection protection sheet 10 reaches the light receiving surface of the cell 4 from the back side, and is further reflected at the interface between the front plate 2 and the atmosphere in the semiconductor power generator main body 1 to receive the light receiving surface of the cell 4. , It is converted into electric power by photoelectric conversion of the cell 4. As a result, the light utilization efficiency is improved.

  FIG. 2 is a longitudinal sectional view showing a schematic configuration of the reflection protection sheet 10 of the first embodiment. The reflection protection sheet 10 is configured by laminating an outer layer 11, an intermediate layer 12, a barrier layer 13, a reflection structure layer 16, and a transmissive protection layer 17 in order from the back side.

The outer layer 11 is provided on the backmost side of the reflection protection sheet 10 and has a role of protecting the reflection structure layer 16 from the back side.
In view of the fact that the outer layer 11 is installed outdoors, it is desirable that the outer layer 11 has weather resistance such as water resistance and durability against ultraviolet rays. For example, a polyethylene resin such as polyethylene terephthalate resin (PET resin), a polypropylene resin, and the like. , Methacrylic resin, polymethylpentene resin, cyclic polyolefin resin, polystyrene resin, acrylonitrile- (poly) styrene copolymer (AS resin), acrylonitrile-butadiene-styrene copolymer (ABS resin), polyvinyl chloride Resin, fluorine resin, poly (meth) acrylic resin, polycarbonate resin, polyester resin, polyamide resin, polyimide resin, polyamideimide resin, polyarylphthalate resin, silicone resin, polysulfone resin, Polyphenylene sul De resins, polyether sulfone resins, triethylene naphthalate resins, polyether imide resins, Epokishin resins, polyurethane resins, acetal resins, that are formed from a cellulose resin or the like.

  Among the above-mentioned resins, polyimide resins, polycarbonate resins, polyester resins, fluorine resins, and polylactic acid resins are preferable as those having high heat resistance, strength, weather resistance, durability, gas barrier properties against water vapor and the like. .

  Examples of the polyester-based resin include polyethylene terephthalate and polyethylene naphthalate. Among these polyester-based resins, polyethylene terephthalate is particularly preferable because it has a good balance between various functions such as heat resistance and weather resistance, and price.

  Examples of the fluororesin include polytetrafluoroethylene (PTFE), perfluoroalkoxy resin (PFA) made of a copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether, and a copolymer of tetrafluoroethylene and hexafluoropropylene (FEP). ), Copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether and hexafluoropropylene (EPE), copolymer of tetrafluoroethylene and ethylene or propylene (ETFE), polychlorotrifluoroethylene resin (PCTFE), ethylene and chlorotrifluoroethylene Copolymer (ECTFE), vinylidene fluoride resin (PVDF), vinyl fluoride resin (PVF), and the like. Among these fluororesins, polyvinyl fluoride resin (PVF) and a copolymer of tetrafluoroethylene and ethylene or propylene (ETFE) which are excellent in strength, heat resistance, weather resistance and the like are particularly preferable.

  Examples of the above-mentioned cyclic polyolefin-based resin include polymerizing cyclic dienes such as a) cyclopentadiene (and derivatives thereof), dicyclopentadiene (and derivatives thereof), cyclohexadiene (and derivatives thereof), norbornadiene (and derivatives thereof), and the like. And b) a copolymer obtained by copolymerizing the cyclic diene with one or more olefinic monomers such as ethylene, propylene, 4-methyl-1-pentene, styrene, butadiene, and isoprene. It is done. Among these cyclic polyolefin resins, cyclopentadiene (and derivatives thereof), dicyclopentadiene (and derivatives thereof) or norbornadiene (and derivatives thereof) such as polymers having excellent strength, heat resistance, and weather resistance are particularly preferred. preferable.

  In addition, as a formation material of the outer layer 11, the above-mentioned synthetic resin can be used 1 type or in mixture of 2 or more types. In addition, various additives and the like can be mixed in the forming material of the outer layer 11 for the purpose of improving and modifying processability, heat resistance, weather resistance, mechanical properties, dimensional stability, and the like. Examples of the additive include a lubricant, a crosslinking agent, an antioxidant, an ultraviolet absorber, a light stabilizer, a filler, a reinforcing fiber, a reinforcing agent, an antistatic agent, a flame retardant, a flame retardant, a foaming agent, and an antifungal agent. And pigments. The method for forming the outer layer 11 is not particularly limited, and known methods such as an extrusion method, a cast method, a T-die method, a cutting method, and an inflation method are employed.

  The outer layer 11 may contain an ultraviolet stabilizer or a polymer having an ultraviolet stabilizing group bonded to a molecular chain. By this ultraviolet stabilizer or ultraviolet stabilizer, radicals generated by ultraviolet rays, active oxygen, and the like are inactivated, and the ultraviolet stability, weather resistance, and the like of the reflection protection sheet 10 can be improved. As the UV stabilizer or UV stabilizer, a hindered amine UV stabilizer or a hindered amine UV stabilizer having high stability to UV is preferably used.

  In addition, as a forming material of the outer layer 11, what mixed the above-mentioned synthetic resin 1 type (s) or 2 or more types can be used. In addition, various additives and the like can be mixed in the forming material of the outer layer 11 for the purpose of improving and modifying processability, heat resistance, weather resistance, mechanical properties, dimensional stability, and the like. Examples of the additive include a lubricant, a crosslinking agent, an antioxidant, an ultraviolet absorber, a light stabilizer, a filler, a reinforcing fiber, a reinforcing agent, an antistatic agent, a flame retardant, a flame retardant, a foaming agent, and an antifungal agent. And pigments. The method for forming the outer layer 11 is not particularly limited, and known methods such as an extrusion method, a cast forming method, a T-die method, a cutting method, and an inflation method are employed.

  The intermediate layer 12 desirably has good adhesion to two layers in contact with the intermediate layer 12, that is, the outer layer 11 and the barrier layer 13, and is used to supplement various properties such as durability and cushioning properties. Examples of materials include polyurethane resins, silicone resins, polyimide resins, epoxy resins, polyethylene resins, polypropylene resins, polymethylpentene resins, cyclic polyolefin resins, and acrylonitrile- (poly) styrene copolymers. (AS resin), polystyrene resins such as acrylonitrile-butadiene-styrene copolymer (ABS resin), polyvinyl chloride resins, polycarbonate resins, polyester resins, polyamide resins, polyamideimide resins, polyaryl phthalate resins Resin, polysulfone resin, polyphenylenes Examples thereof include a fido resin, a polyethersulfone resin, a reethylene naphthalate resin, a polyetherimide resin, an acetal resin, and a cellulose resin, and those obtained by mixing one or more of these polymers are used. .

By providing the intermediate layer 12, it is possible to make up for performance that is insufficient with other layers alone. For example, a silicone resin is used to improve durability, cushioning properties, and the like. In particular, in the case of a semiconductor power generation device for outdoor use, the heat rise of the semiconductor power generation device 100 during sunshine is significant, and the reflection protection sheet 10 made from a resin material is warped, which may cause a failure of the semiconductor power generation device 100. In addition, a metal layer may be used as the intermediate layer 12 for the purpose of imparting an important high barrier property in order to maintain high power generation efficiency.
The thickness of the intermediate layer 12 is preferably 3 to 10 μm from the viewpoint of adhesion and cost.

The barrier layer 13 is desirably a material having an excellent water vapor barrier property. Specifically, the water vapor permeability is desirably in the range of 0 to 0.5 g / m ² , and inorganic oxides such as silicon oxide, aluminum oxide, magnesium oxide, tin oxide, indium oxide, zinc oxide, and tungsten oxide. Or it is shape | molded from those mixtures.
In particular, silicon oxide is desirable because it is not only excellent in oxygen and water vapor barrier properties but also has high resistance to acids and is not eroded by acetic acid generated by EVA cross-linking.

  The reflection structure layer 16 is configured by laminating the reflection film 14 along the uneven shape on the uneven surface formed on the back side of the optical structure layer 15.

As a material for forming the optical structure layer 15, a thermosetting resin or a thermoplastic resin having a Vicat softening temperature of 95 ° C. or higher is used in consideration of the heat pressure applied when the semiconductor power generation device 100 is assembled.
The Vicat softening temperature is measured by the B50 method in JIS-K7206.
Further, when the optical structure layer 15 is located closer to the transmissive protective layer 17 than the reflective film 14 as in this embodiment, it is desirable that the optical structure layer 15 has high transparency. Examples of the material used for the optical structure layer 15 include a polymer composition. When a polymer composition is used for the optical structure layer 15, in addition to the polymer composition, for example, a curing agent, a plasticizer, a dispersant, various leveling agents, an ultraviolet absorber, an antioxidant, a viscosity modifier, a lubricant In addition, a light stabilizer and the like may be appropriately blended.

  The polymer composition is not particularly limited as long as it is a thermosetting resin or a thermoplastic resin having a Vicat softening temperature of 95 ° C. or higher. For example, epoxy resin, phenol resin, urea resin, polyurethane Resin, melamine resin, unsaturated polyester resin, alkyd resin, polyimide resin, fluorine resin, silicone resin, polyethylene resin, polypropylene resin, methacrylic resin, polymethylpentene resin, emotion polyolefin Resin, acrylonitrile-butadiene-styrene copolymer (ABS resin), polycarbonate resin, polyamide resin, polyamideimide resin, polyarylphthalate resin, polysulfone resin, polyphenylene sulfide resin, polyethersulfone resin, polyester Ether ether ketone resins, polyethylene naphthalate resins, polyether imide resins, acetal resins, and the like, can be used as a mixture of these polymers alone or in combination.

  Examples of the polyol that is a raw material for the polyurethane resin include a polyol obtained by polymerizing a monomer component containing a hydroxyl group-containing unsaturated monomer, a polyester polyol obtained under conditions of excess hydroxyl group, and the like. These can be used alone or in admixture of two or more.

  Examples of the hydroxyl group-containing unsaturated monomer include (a) 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, allyl alcohol, homoallyl alcohol, Keihi Hydroxyl group-containing unsaturated monomers such as alcohol and crotonyl alcohol, (b) for example ethylene glycol, ethylene oxide, propylene glycol, propylene oxide, butylene glycol, butylene oxide, 1,4-bis (hydroxymethyl) cyclohexane, phenylglycidyl Dihydric alcohols or epoxy compounds such as ether, glycidyl decanoate, Plaxel FM-1 (manufactured by Daicel Chemical Industries, Ltd.) and, for example, acrylic acid, methacrylic acid, maleic acid, fumaric acid, Tonsan, and the like hydroxyl group-containing unsaturated monomers obtained by reaction of an unsaturated carboxylic acid such as itaconic acid. One or more selected from these hydroxyl group-containing unsaturated monomers can be polymerized to produce a polyol.

  The polyols described above are ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, tert-butyl acrylate, ethyl hexyl acrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, N-butyl methacrylate, tert-butyl methacrylate, ethyl hexyl methacrylate, glycidyl methacrylate, cyclohexyl methacrylate, styrene, vinyl toluene, 1-methylstyrene, acrylic acid, methacrylic acid, acrylonitrile, vinyl acetate, vinyl propionate, stearin Vinyl acid, allyl acetate, diallyl adipate, diallyl itaconate, diethyl maleate, vinyl chloride, vinylidene chloride, acrylamide, N-methylol acrylamide, N-butyl One or more ethylenically unsaturated monomers selected from xymethyl acrylamide, diacetone acrylamide, ethylene, propylene, isoprene and the like, and a hydroxyl group-containing non-functional group selected from the above (a) and (b) It can also be produced by polymerizing a saturated monomer.

  The number average molecular weight of a polyol obtained by polymerizing a monomer component containing a hydroxyl group-containing unsaturated monomer is from 1,000 to 500,000, preferably from 5,000 to 100,000. The hydroxyl value is 5 or more and 300 or less, preferably 10 or more and 200 or less, more preferably 20 or more and 150 or less.

  The polyester polyol obtained under the condition of excess hydroxyl group is (c), for example, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl. Glycol, hexamethylene glycol, decamethylene glycol, 2,2,4-trimethyl-1,3-pentanediol, trimethylolpropane, hexanetriol, glycerin, pentaerythritol, cyclohexanediol, hydrogenated bisphenol A, bis (hydroxymethyl) Polyhydric alcohols such as cyclohexane, hydroquinone bis (hydroxyethyl ether), tris (hydroxyethyl) isosinurate, xylylene glycol, and (d) maleic acid, for example. Polybasic acids such as fumaric acid, succinic acid, adipic acid, sebacic acid, azelaic acid, trimetic acid, terephthalic acid, phthalic acid, isophthalic acid, and other polyvalent acids such as propanediol, hexanediol, polyethylene glycol, and trimethylolpropane It can be produced by reacting under conditions where the number of hydroxyl groups in the alcohol is greater than the number of carboxyl groups of the polybasic acid.

  The number average molecular weight of the polyester polyol obtained under the above hydroxyl group-excess conditions is 500 or more and 300,000 or less, preferably 2000 or more and 100,000 or less. The hydroxyl value is 5 or more and 300 or less, preferably 10 or more and 200 or less, more preferably 20 or more and 150 or less.

  The polyol used as the polymer material of the polymer composition is obtained by polymerizing the above-described polyester polyol and a monomer component containing the above-mentioned hydroxyl group-containing unsaturated monomer, and is a (meth) acryl unit. Etc. are preferred. By using such polyester polyol or acrylic polyol as a polymer material, weather resistance can be improved, and yellowing of the optical structure layer 15 can be suppressed. In addition, any one of this polyester polyol and acrylic polyol may be used, and both may be used.

  The number of hydroxyl groups in the above-described polyester polyol and acrylic polyol is not particularly limited as long as it is 2 or more per molecule, but if the hydroxyl value in the solid content is 10 or less, the number of crosslinking points decreases, and the solvent resistance Film properties such as heat resistance, water resistance, heat resistance and surface hardness tend to decrease.

Further, by adding a filler to the material forming the optical structure layer 15, it is possible to impart scattering properties and reduce the influence of the re-condensing efficiency due to the incident angle of external light. Moreover, it becomes possible to improve heat resistance by containing a filler.
When a filler is mixed in the material forming the optical structure layer 15, it is desirable to select a material having a refractive index that can improve the heat resistance of the optical structure layer 15 and that is suitable for the required scattering properties. . The inorganic material constituting the filler is not particularly limited, and an inorganic oxide is preferable. As the inorganic oxide, metal oxides such as silicon oxide and zinc sulfide can be used, but metal oxides such as titanium oxide and aluminum oxide are particularly desirable. Silicon oxide hollow particles can also be used. Of these, titanium oxide is preferable because of its high refractive index and easy dispersibility. The shape of the filler may be any particle shape such as a spherical shape, a needle shape, a plate shape, a scale shape, and a crushed shape, and is not particularly limited.

  The lower limit of the average particle diameter of the filler is preferably 0.1 μm, and the upper limit is preferably 30 μm. If the average particle diameter is smaller than 0.1 μm, light is not sufficiently reflected. Further, if the average particle size is larger than 30 μm, the moldability is poor.

  As a minimum of the compounding quantity with respect to 100 parts of polymer compositions of a filler, 30 parts is preferable in conversion of solid content. On the other hand, the upper limit of the amount of the filler described above is preferably 100 parts. This is because if the blending amount of the filler is less than 30 parts, light cannot be sufficiently reflected. On the contrary, if the blending amount exceeds the above range, the moldability is poor.

  As the above-mentioned filler, a material having an organic polymer fixed on its surface may be used. Thus, by using the filler fixed to the organic polymer, the dispersibility in the polymer composition and the affinity with the polymer composition can be improved. The organic polymer is not particularly limited with respect to its molecular weight, shape, composition, presence or absence of a functional group, and any organic polymer can be used. Moreover, about the shape of an organic polymer, the thing of arbitrary shapes, such as a linear form, a branched form, and a crosslinked structure, can be used.

  Specific resins constituting the above-mentioned organic polymer include, for example, (meth) acrylic resin, polystyrene, polyvinyl acetate, polyolefin such as polyethylene and polypropylene, polyester such as polyvinyl chloride, polyvinylidene chloride, polyethylene terephthalate, and the like. And a resin partially modified with a functional group such as an amino group, an epoxy group, a hydroxyl group, or a carboxyl group. Among them, those having an organic polymer containing a (meth) acryl unit such as a (meth) acrylic resin, a (meth) acrylic-styrene resin, and a (meth) acrylic-polyester resin have a film forming ability. Is preferred. On the other hand, a resin having compatibility with the above-described polymer composition is preferable, and therefore, a resin having the same composition as the material forming the optical structure layer 15 is most preferable.

  As a material for forming the optical structure layer 15, it is particularly preferable to use a polyol having a cycloalkyl group. By introducing a cycloalkyl group into the polyol as the polymer composition, the hydrophobicity of the polymer composition, such as water repellency and water resistance, is increased, and the flexibility and dimensional stability under high temperature and high humidity conditions are improved. Can be improved. Further, the basic properties of the coating film such as weather resistance, hardness, feeling of holding, and solvent resistance of the optical structure layer 15 are improved. Furthermore, the affinity with the filler having the organic polymer fixed on the surface and the dispersibility of the filler are further improved.

  Moreover, it is good to contain isocyanate as a hardening | curing agent in a polymer composition. Thus, by containing an isocyanate hardening | curing agent in a polymer composition, it becomes a much stronger bridge | crosslinking structure and the film physical property of the optical structure layer 15 further improves. As this isocyanate, the same substance as the above-mentioned polyfunctional isocyanate compound is used. Of these, aliphatic isocyanates that prevent yellowing of the coating are preferred.

  The filler may contain an organic polymer inside. Thereby, moderate softness and toughness can be imparted to the inorganic material that is the core of the filler.

  An organic polymer containing an alkoxy group may be used as the organic polymer, and the content is not particularly limited, but is preferably 0.01 mmol or more and 50 mmol or less per 1 g of filler. The alkoxy group can improve the affinity with the polymer composition and the dispersibility in the polymer composition.

  The above-described alkoxy group represents an RO group bonded to a metal element that forms a fine particle skeleton. R is an alkyl group which may be substituted, and the RO groups in the fine particles may be the same or different. Specific examples of R include methyl, ethyl, n-propyl, isopropyl, n-butyl and the like. The same metal alkoxy group as the metal constituting the filler is preferably used. When the filler is colloidal silica, it is preferable to use an alkoxy group having silicon as a metal.

  The content of the organic polymer in the filler to which the organic polymer is fixed is not particularly limited, but is preferably 0.5% by mass or more and 50% by mass or less based on the filler.

The concavo-convex shape integrally formed on the back side of the optical structure layer 15 is formed for the purpose of adjusting light by reflecting incident light in a specific direction, and can be suitably reflected. The shape may be a so-called faceted shape or conical shape such as a V-shaped groove or a polygonal pyramid shape, or may be a shape in which the tops of the faceted shape and the conical shape are rounded.
Such an uneven shape of the optical structure layer 15 may be formed over the entire back surface of the optical structure layer 15, or the front surface so as to correspond to the arrangement position of the cells 4 in the semiconductor power generator main body 1. You may form in the arrangement | positioning position which satisfy | fills the clearance gap between these adjacent cells 4 in view.

3A to 3C show examples of the uneven shape of the optical structure layer 15. The concave / convex shape of the optical structure layer 15 is determined according to the type and installation location of the semiconductor power generation device 100. The pyramid shape shown in FIG. 3 (a), the V-groove shape shown in FIG. 5 (b), and FIG. The conical shape shown in c) is preferable.
Further, since sunlight that is a light source of the semiconductor power generation device 100 is approximated to a light source located at infinity from the semiconductor power generation device 100, the sunlight is a rooftop, a roof, or the like where the semiconductor power generation device 100 is installed. Then, the light enters the semiconductor power generation device 100 as parallel light. Note that not all light is parallel light, but scattered light that is reflected by the surrounding objects is present, but most of the light is incident as parallel light. A prism shape having a flat surface is effective for dimming such parallel light.

4A and 4B are side views showing the apex angle of an example of the concavo-convex shape of the optical structure layer 15. The apex angle θ of the concavo-convex shape indicates an angle formed by the line L1 and the line L2 that are parallel to the linearly formed region on the two opposing side surfaces that form the concavo-convex shape. The same applies to a shape having a rounded top as shown in FIG.
That is, the concavo-convex shape is formed by alternately arranging a plurality of convex portions and concave portions, and the apex angle θ is in the range of 111 ° to 137 °, preferably in the range of 120 ° to 135 °. Is set to

  As a method for forming the irregular shape of the optical structure layer 15, a plastic raw material is fed into a heating cylinder with a screw or a plunger, heated and fluidized, passed through a die at the tip, given a shape, and cooled and solidified with water or air. There is an extrusion method to make a long product.

  In addition, as another method of forming the uneven shape, for example, a relief pattern is drawn by electron beam on a resin or the like, or a relief pattern is formed by cutting tools, etc., and the relief pattern thus formed is formed into a metal plate by electroforming. Relief patterns can be replicated in large quantities by preparing an original by raising it and transferring the pattern from the original by an embossing method. Further, instead of transferring by the embossing method, the pattern may be transferred by a molding method using an ultraviolet curable resin.

  The reflective film 14 is disposed on the surface of the concavo-convex shape of the optical structure layer 15 as described above so as to follow the shape thereof, and thus the reflective structure layer 16 is corrugated according to the shape of the concavo-convex shape. It has a shape.

  The reflective film 14 has a function of reflecting incident light, and the material of the reflective film 14 is not particularly limited as long as it has reflectivity and can be deposited. (Al), gold (Au), silver (Ag), platinum (Pt), nickel (Ni), tin (Sn), chromium (Cr), zirconium (Zr), and other metals, and alloys thereof. . Further, a high refractive index material such as zinc oxide or zinc sulfide may be included. Among these, aluminum has a high reflectance in the ultraviolet, visible, and near infrared regions, and it is possible to prevent internal erosion by forming an oxide film on the surface. Moreover, there exists an advantage that it has high water vapor | steam barrier property. Further, silver has an advantage that the reflectance is higher than that of aluminum in the visible and near infrared regions. Gold absorbs on the short wavelength side of the visible region, but has a higher reflectance than aluminum at wavelengths of 600 nm or longer. Furthermore, these three types of metals have an advantage that they are very difficult to be eroded, so that they are desirable as materials used for the reflective film 14.

  The reflective film 14 is formed by evaporating the metal along the uneven shape of the optical structure layer 15. The deposition means is not particularly limited as long as the metal can be deposited without causing deterioration such as shrinkage and yellowing to the uneven shape. (A) Vacuum deposition method, sputtering method, ion plating method, ion cluster Physical vapor deposition method (Physical Vapor Deposition method; PVD method) such as beam method, (b) Chemical vapor deposition method (Chemical, such as plasma chemical vapor deposition method, thermal chemical vapor deposition method, photochemical vapor deposition method) Vapor Deposition method (CVD method) is employed. Among these vapor deposition methods, a vacuum vapor deposition method and an ion plating method that can form a high-quality reflective film 14 with high productivity are preferable.

  The reflective film 14 may have a single layer structure or a multilayer structure of two or more layers. Thus, by making the reflective film 14 have a multilayer structure, the deterioration of the uneven shape can be reduced by reducing the heat load applied during vapor deposition, and the adhesion between the uneven shape and the reflective film 14 can be improved. . At this time, a metal oxide layer may be provided on the metal film. The vapor deposition conditions in the physical vapor deposition method and the chemical vapor deposition method described above are appropriately designed according to the resin type of the reflective structure layer 16, the thickness of the reflective film 14, and the like.

  The lower limit of the thickness of the reflective film 14 is preferably 10 nm, and particularly preferably 20 nm. On the other hand, the upper limit of the thickness of the reflective film 14 is preferably 200 nm, and particularly preferably 100 nm. If the thickness of the reflective film 14 is smaller than the lower limit of 10 nm, the light incident on the reflective film 14 cannot be sufficiently reflected. Moreover, even if the thickness is 20 nm or more, the light reflected by the reflective film 14 does not increase. On the other hand, when the thickness of the reflective film 14 exceeds the upper limit of 200 nm, cracks that can be visually confirmed occur in the reflective film 14, and cracks that cannot be visually confirmed occur if the thickness is 100 nm or less.

  In addition, as the thickness of the base on which the reflective film 14 is formed, that is, the layer in contact with the reflective film 14, the thickness of the thinnest portion is desirably 100 μm or more. When the thickness is less than 100 μm, the base material is easily bent, and the reflective film is easily cracked. In the present embodiment, since the transmissive protective layer 17 and the optical structure layer 15 serve as a base on which the reflective film 14 is formed, the total thickness of both is preferably 100 μm or more.

  Moreover, it is preferable that the outer surface of the reflective film 14 is subjected to a top coat treatment. Thus, by performing a top coat process on the outer surface of the reflective film 14, the reflective film 14 is sealed and protected, and deterioration over time can be suppressed.

  Examples of the topcoat agent used in the above-described topcoat treatment include a polyester topcoat agent, a polyamide topcoat agent, a polyurethane topcoat agent, an epoxy topcoat agent, a phenol topcoat agent, and a (meth) acrylic top. Examples thereof include a coating agent, a polyvinyl acetate top coating agent, a polyolefin top coating agent such as polyethylene aly polypropylene, and a cellulose top coating agent. Among such topcoat agents, a polyester-based topcoat agent that has high adhesive strength with the reflective film 14 and contributes to surface protection of the reflective film 14, sealing of defects, and the like is particularly preferable.

The coating amount (in terms of solid content) of the above-mentioned topcoat agent is preferably 3 g / m ² or more and 7 g / m ² or less. If the coating amount of the top coat agent is smaller than 3 g / m ² , the effect of sealing and protecting the reflective film 14 may be reduced. On the other hand, even if the coating amount of the top coat agent exceeds 7 g / m ² above, the sealing and protecting effect of the reflective film 14 does not increase so much, and the thickness of the reflective protective sheet 10 increases.

  In addition, in the above-mentioned top coat agent, various additives such as a silane coupling agent for improving tight adhesion, an ultraviolet absorber for improving weather resistance and the like, an inorganic filler for improving heat resistance and the like Can be mixed as appropriate. The amount of the additive to be mixed is preferably 0.1% by weight or more and 10% by weight or less from the balance between the effect expression of the additive and the function inhibition of the topcoat agent. If the above-mentioned additive is less than 0.1% by weight, close adhesion, weather resistance and heat resistance cannot be sufficiently obtained, and if it is more than 10% by weight, the function of the topcoat agent is inhibited.

  In addition, in order to improve the tight adhesion between the reflective film 14 and the optical structure layer 15, it is preferable to perform a surface treatment on the concavo-convex shape surface of the optical structure layer 15 that is the deposition target surface of the reflective film 14. Examples of such surface treatment include (a) corona discharge treatment, ozone treatment, low temperature plasma treatment using oxygen gas or nitrogen gas, glow discharge treatment, oxidation treatment using chemicals, and (b) primer. Examples of the coating treatment include undercoating, anchor coating, vapor deposition anchor coating, and the like. Among these surface treatments, corona discharge treatment and anchor coat treatment that improve adhesion strength with the uneven shape and contribute to the formation of a dense and uniform reflective film 14 are preferable.

  Examples of the anchor coating agent used in the above-described anchor coating treatment include a polyester anchor coating agent, a polyamide anchor coating agent, a polyurethane anchor coating agent, an epoxy anchor coating agent, a phenol anchor coating agent, and a (meth) acrylic anchor. Examples thereof include a coating agent, a polyvinyl acetate anchor coating agent, a polyolefin anchor coating agent such as polyethylene aly polypropylene, and a cellulose anchor coating agent. Among these anchor coating agents, polyester anchor coating agents that can further improve the adhesive strength of the reflective film 14 are particularly preferable.

The coating amount (in terms of solid content) of the above-described anchor coating agent is preferably 1 g / m ² or more and 3 g / m ² or less. When the coating amount of the anchor coating agent is less than 1 g / m ^{2, the} effect of improving the adhesion of the reflective film 14 is reduced. On the other hand, when the coating amount of the anchor coating agent is more than 3 g / m ² , the strength, durability and the like of the reflection protection sheet 10 may be reduced.

  In the above-mentioned anchor coating agent, various additives such as a silane coupling agent for improving tight adhesion, an anti-blocking agent for preventing blocking, and an ultraviolet absorber for improving weather resistance, etc. It can mix suitably.

  It is desirable that the permeable protective layer 17 has excellent heat resistance, moisture resistance, electrical characteristics (particularly overall voltage resistance) and mechanical characteristics. Specific examples include a fluororesin film, a fluororesin coating film, and PET for electrical insulation. The thickness of the permeable protective layer 17 is desirably 180 μm to 350 μm from the viewpoint of electrical insulation and cost.

As an example of a method for producing the reflection protection sheet 10 composed of the above members, first, an optical structure layer having a concavo-convex shape on a transparent protective layer 17 by a UV molding method using a metal plate or an extrusion molding method. 15 is formed, and the reflective film 14 is formed on the uneven shape by vapor deposition or the like. Then, the barrier layer 13 is formed on the reflective film 14 by vapor deposition or the like, and the barrier layer 13 and the outer layer 11 are bonded using the intermediate layer 12.
In such a reflection protective sheet 10, the portion of the optical structure layer 15 where the reflective film 14 is formed on the concave and convex shape is the light reflecting concave and convex portion, and the light incident from the semiconductor power generator main body 1 is incident on the semiconductor power generator main body 1. Will be reflected.

  As described above, the reflection protective sheet 10 of the present embodiment includes the transmissive protective layer 17 that transmits the light emitted from the back surface of the semiconductor power generation device main body 1 through the semiconductor power generation device main body 1 and the transmission. A reflective structure layer 16 that is disposed on the back side of the reflective protective layer 17 and reflects the light transmitted through the transparent protective layer 17 toward the transparent protective layer 17; and a reflective structure layer 16 that is disposed on the back side of the reflective structural layer 16. The outer layer 11 that protects the reflective structure layer 16 is provided.

  In the semiconductor power generation device 100 having the reflection protective sheet 10 having the above-described configuration, the light transmitted through the filling layer 3 and the cell 4 of the semiconductor power generation device main body 1 is reflected on the back surface of the semiconductor power generation device main body 1. Incident on the sheet 10. The light incident on the reflection protection sheet 10 passes through the transmissive protection layer 17 and is reflected toward the semiconductor power generation device 100 by the light reflection concavo-convex portion including the concavo-convex shape in the reflective structure layer 16 and the reflective film 14. . Then, the light recursed in the semiconductor power generation device main body 1 is received by the cell 4 to contribute to power generation, thereby improving the light use efficiency.

In the reflection protection sheet 10 of the present embodiment, the reflection structure 14 is formed by laminating the reflection film 14 on the concave and convex shape of the optical structure layer 15 to reflect light with high efficiency toward the front side. Can do. By making this reflected light enter from the back side of the semiconductor power generator main body 1, it is possible to improve power generation efficiency.
Further, since the material for forming the optical structure layer 15 is a thermosetting resin or a thermoplastic resin having a Vicat softening temperature of 95 ° C. or higher, the optical structure is assembled when assembling the semiconductor power generation device 100 mounted with the reflection protection sheet 10. There is little deformation of the layer, and a constant quality can be maintained.

Moreover, since the barrier layer 13 having a water vapor transmission rate of 0 to 0.5 g / m ² is provided between the reflective film 14 and the outer layer 11, the semiconductor power generator in which the reflective protection sheet 10 is disposed on the back side. It is possible to prevent water vapor from penetrating into the main body 1 and prevent corrosion of the electrodes used in the semiconductor power generator main body 1 and deterioration of the sealing resin.
Note that if the water vapor permeability exceeds 0.5 g / m ² , corrosion of the electrode or deterioration of the sealing resin may occur, which is not desirable. In this respect, by setting the water vapor transmission density within the above range, corrosion of the electrode and deterioration of the sealing resin can be surely avoided.
Furthermore, by disposing the barrier layer 13 between the reflective structure layer 16 and the outer layer 11, it is possible to suppress the absorption of light until the incident light reaches the reflective structure layer 16 as much as possible.

  Furthermore, since the barrier layer 13 contains an inorganic oxide, the oxygen barrier property and the water vapor barrier property can be improved, and further, the heat resistance can be improved.

Further, when the uneven shape of the optical structure layer 15 is a prism shape such as a facet shape or a conical shape, the reflectance can be improved. On the other hand, when the concavo-convex shape is an aspherical lens having a high aspect ratio, it is not preferable because it has a scattering property but absorbs light so much that it may cause a decrease in retroreflectance.
In addition, when the concavo-convex shape is a shape with a rounded top of the facet shape, or when the top of the conical shape is rounded, the concavo-convex shape is maintained in the manufacturing process while maintaining good reflectance. It is possible to prevent the shape from being damaged.

  Moreover, in the reflection protection sheet 10, when the angle θ of the top of the concavo-convex shape is set in the range of 111 ° to 137 °, the refractive index of the sealing resin and glass used in the semiconductor power generation device 100 is about In the case of 1.5, it is possible to prevent total reflection at the interface between the glass and air and the incidence of the reflected light on the optical structure layer 15. On the other hand, when the apex angle θ exceeds 137 °, total reflection is less likely to occur at the interface between glass and air, which is not preferable because the possibility that the re-condensing efficiency is lowered is increased. Further, when the apex angle θ is less than 111 °, there is a high possibility that a part of the light reflected by the concavo-convex shape will collide in the optical structure layer 15, and the possibility that the re-condensing efficiency is reduced is not preferable. .

  Furthermore, when the angle θ of the top of the concavo-convex shape is set in the range of 120 ° to 135 °, it can be stably formed at an angle in the range of total reflection at the interface between glass and air, Since a part of the light reflected by the uneven shape does not collide in the optical structure layer 15, the reflectance is not lowered and the re-condensing efficiency can be maintained high.

  Then, according to the semiconductor power generation device 100 of the present embodiment, since the reflection protection sheet 10 is provided, light can be efficiently incident on the cells 4 of the semiconductor power generation device main body 1. When assembling, there is little deformation of the optical structure layer, and a certain quality can be maintained.

  Next, the reflection protection sheet 20 of 2nd Embodiment is demonstrated using FIG. FIG. 5 is a longitudinal sectional view showing a schematic configuration of the reflection protection sheet 20 of the second embodiment. In FIG. 5, the same components as those in FIG. 2 are denoted by the same reference numerals, and detailed description thereof is omitted.

In the reflection protection sheet 10 of the first embodiment, the barrier layer 13 is disposed only between the intermediate layer 12 and the reflection film 14, whereas the reflection protection sheet 20 of the fifth embodiment has the barrier layer 13. The layer 13 is also disposed between the reflective film 14 and the uneven shape of the optical structure layer 15.
In other words, the reflection protection sheet 20 of the second embodiment has a structure in which the reflection film 14 is sandwiched between the barrier layers 13 and 13, and the reflection film 14 and the optical structure layer 15 are between the two barrier layers 13. The barrier layer 13 is a part of the reflective structure layer 16. In other words, in the second embodiment, the reflective structure layer 26 is composed of the optical structure layer 15, the barrier layer 13, and the reflective film 14.

  Thus, by making the reflective film 14 sandwiched between the pair of barrier layers 13, contact of the reflective film 14 with water vapor and oxygen can be suppressed as much as possible, and oxidation of the reflective film can be reliably prevented. Is possible.

  Next, the reflection protection sheet 30 of 3rd Embodiment is demonstrated using FIG. FIG. 6 is a longitudinal sectional view showing a schematic configuration of the reflection protection sheet 30 of the third embodiment. In FIG. 6, the same components as those in FIG. 2 are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the reflection protective sheet 10 of the first embodiment, the uneven shape of the optical structure layer 15 of the reflective structure layer 16 faces the back side, and the reflective film 14 is laminated in the uneven shape facing the back side. The reflection protection sheet 30 of the third embodiment has a reflection structure layer 16 in which the uneven shape of the optical structure layer 15 faces the front surface side, and the reflection film 14 is laminated in the uneven shape facing the front surface side. Yes. A barrier layer 13 and a transmissive protective layer 17 are stacked on the reflective film 14.

In the reflection protection sheet 30 of the third embodiment, since the reflection film 14 is disposed on the front side of the reflection structure layer 16, the material used for the optical structure layer 15 does not need to be transmissive. This makes it possible to select a material that satisfies other required characteristics other than the permeability.
In addition, since the barrier layer 13 is disposed between the transmissive protective layer 17 and the reflective film 14, it is possible to suppress the deterioration of the reflective film due to acetic acid generated by crosslinking of the filling layer.

  Thus, it is preferable that the front surface of the transparent protective layer 17 laminated on the reflective film 14 via the barrier layer 13 is generally smooth, and the most when the reflective protective sheet 30 is viewed from the cross section. It is desirable that the upper surface and the lowermost surface (in this embodiment, the front surface of the transmissive protective layer 17 and the back surface of the outer layer 11) are substantially parallel.

  If the front surface of the permeable protective layer 17 is not smooth, it is likely to be scratched by friction during transportation and assembly, and the re-condensing efficiency may decrease due to a decrease in transmittance due to the scratch. . In addition, there is a high possibility that air bubbles will be involved during assembly, due to phenomena such as refraction, scattering, reflection, etc. due to the occurrence of peeling starting from the air bubbles involved and the difference in refractive index between the bubbles and the material in contact with the air bubbles. There is a possibility that the re-condensing efficiency is lowered. In addition, there is a high possibility that fine dust such as dust will be entrained during transportation and peeling will occur.

  In addition, when the uppermost surface and the lowermost surface when the reflection protection sheet 30 is viewed from a cross section are not substantially parallel, there is a high possibility that air bubbles will be involved at the time of assembly. In addition, there is a possibility that the re-condensing efficiency is lowered due to a phenomenon such as refraction, scattering, and reflection due to a difference in refractive index between the bubble and the material in contact with the bubble. Moreover, when storing in the state in which the reflection protection sheet 30 is laminated, there is a possibility that the pressure load is locally increased and the smoothness of the reflection protection sheet 30 cannot be maintained.

  As a specific numerical value relating to the smoothness, the surface roughness Ra is desirably 20 μm or less, and more desirably 5 μm or less. When Ra exceeds 5 μm, dust and the like are likely to adhere, and when Ra exceeds 20 μm, scratches due to friction and the like are likely to occur.

  As mentioned above, although embodiment in this invention was described in detail, unless it deviates from the technical idea of this invention, it is not limited to these, A some design change etc. are possible.

(Measurement of power generation)
Next, examples will be described. The reflection protection sheet 10 of Example and the sheets of Comparative Examples 1 to 3 were prepared, and these were disposed on the back surface of the semiconductor power generator main body 1 to measure the amount of power generation.

(Reflective protective sheet of Example 1)
A reflection protective sheet 20 of the first embodiment shown in FIG. 2 was produced. In this reflection protective sheet, the unevenness of the optical structure layer 15 is a V-shaped prism having an apex angle of 120 °, the average pitch of the protrusions is 200 μm, and the length of the unevenness of the unevenness is added to the thickness of the reflection film 14 In other words, the height of the light reflection uneven portion composed of the uneven shape and the reflective film 14 was set to 58 μm.
The transparent protective layer 17 was formed from a PET film, and a concave-convex shape was prepared using the PET film and an ultraviolet curable acrylic resin as the molding base material of the optical structural layer 15 in the reflective structural layer 16. In addition, aluminum deposition was performed as the reflective film 14. Further, a PET film was used for the outer layer 11.

(Sheet of Comparative Example 1)
A black paper was used as the sheet of Comparative Example 1 assuming no reflection at all.

(Sheet of Comparative Example 2)
White PET was used as the sheet of Comparative Example 2 assuming a scattering pattern without a reflective film.

(Sheet of Comparative Example 3)
The reflective film 14 was removed from the reflective protective sheet 20 of Example 1, and a sheet in which 40% of a titanium oxide filler was mixed in the optical structure layer 15 was produced.

(Measuring method)
FIG. 7 shows a schematic diagram of the measuring method. Assuming noon sunlight, the light source 101 was installed using parallel light having an incident angle of about 0 degrees as a measurement light source. Further, the power meter 102 was used for the measurement of the refocusing efficiency. Assuming the configuration of the semiconductor power generation device 100, the reflection protection sheet 20 of the example or the sheets of Comparative Examples 1 to 3, the power meter 102, and the blue plate glass 103 were laminated in this order. In addition, each layer was immersed using glycerin 104 in order to match the refractive index.

(Measurement result)
The measurement results are shown in Table 1. The rate of increase indicates the rate of increase in the amount of power generation based on Comparative Example 1.

From Table 1, it can confirm that the electric power generation amount is improving rather than the comparative example 1 which is Example 1 and the comparative example 2 and the comparative example 3 which are black paper.
However, Comparative Example 3 in which the reflective film is removed and a titanium oxide filler is added shows almost the same value as Comparative Example 2 that is white PET, whereas Example 1 of the reflective protective sheet 10 of the first embodiment. Showed a very high power generation rate and an increase rate relative to Comparative Examples 2 and 3. Therefore, it has been confirmed that it is effective to improve the power generation amount of the semiconductor power generation device 100 by forming an uneven shape and providing a reflective film like the reflection protection sheet 10 of the embodiment.

(Evaluation of changes in the amount of power generated by the shape of the light reflection unevenness)
(Reflective protective sheet of Example 1)
A reflection protective sheet 20 of the embodiment shown in FIG. 2 was produced. In this reflection protective sheet, the unevenness of the optical structure layer 15 is a V-shaped prism having an apex angle of 120 °, the average pitch of the protrusions is 200 μm, and the length of the unevenness of the unevenness is added to the thickness of the reflection film 14 In other words, the height of the light reflection uneven portion composed of the uneven shape and the reflective film 14 was set to 58 μm.
The transparent protective layer 17 is formed from a PET film, and is formed into a PET film using the molding substrate of the optical structural layer 15 in the reflective structural layer 16 as the transparent protective layer 17. The transparent protective layer 17 is uneven using an ultraviolet curable acrylic resin. A shape was made. In addition, aluminum deposition was performed as the reflective film 15. Further, a PET film was used as the outer layer 11.

(Sheet of Comparative Example 1)
A black paper was used as the sheet of Comparative Example 1 assuming no reflection at all.

(Sheet of Comparative Example 2)
White PET was used as the sheet of Comparative Example 2 assuming a scattering pattern without a reflective film.

(Sheet of Comparative Example 3)
Assuming a case where the top of the uneven shape of the optical structure layer 15 in the reflection protective sheet of Example 1 is crushed, a sheet having a shape in which the tip of the uneven shape of the optical structure layer 15 is flattened by 25% is produced. It was set as Comparative Example 3.

(Sheet of Comparative Example 4)
Assuming a case where the top of the uneven shape of the optical structure layer 15 in the reflection protection sheet of Example 1 is crushed, a sheet having a shape in which the tip of the uneven shape of the optical structure layer 15 is 50% flat is produced, It was set as Comparative Example 4.

(Measuring method)
FIG. 7 shows a schematic diagram of the measuring method. Assuming noon sunlight, the light source 101 was installed using parallel light having an incident angle of about 0 degrees as a measurement light source. Further, the power meter 102 was used for the measurement of the refocusing efficiency. Assuming the configuration of the semiconductor power generation device 100, the reflection protection sheet 20 of the example or the sheets of Comparative Examples 1 to 3, the power meter 102, and the blue plate glass 103 were laminated in this order. In addition, each layer was immersed using glycerin 104 in order to match the refractive index.

(Measurement result)
The measurement results are shown in Table 2. The rate of increase indicates the rate of increase in the amount of power generation based on Comparative Example 1.

From Table 2, it can be seen that in Comparative Examples 3 and 4, the amount of power generation is lower than that in Example 1, although there is no deterioration up to Comparative Example 2.
Therefore, it was confirmed that the power generation efficiency deteriorates when the shape of the light reflection uneven portion is deformed.

(Shape change evaluation)
Regarding the reflection protection sheet 30 of the third embodiment, an optical structure layer 15 having a V-groove uneven shape with an apex angle of 120 ° was produced.
The material for forming the optical structure layer 15 includes (a) polyurethane resin and epoxy resin which are thermosetting resins, (b) polystyrene which is a Vicat softening temperature 79 ° C. and chloride which is a Vicat softening temperature 85 ° C. which is a thermoplastic resin. Vinyl, polystyrene with Vicat softening temperature 88 ° C, acrylic with Vicat softening temperature 98 ° C, polystyrene with Vicat softening temperature 99 ° C, acrylic with Vicat softening temperature 115 ° C, polypropylene with Vicat softening temperature 131 ° C, polycarbonate with Vicat softening temperature 148 ° C Using.
And the reflective protection sheet 30 of 3rd Embodiment was produced using the optical structure layer 15 formed from these each material, and it installed in the environment of 150 degreeC-30min-1atm. Then, the presence or absence of the change of the shape of the reflective film 14 was evaluated using the microscope from the transparent protective layer 17 side.

Table 3 shows the evaluation results.

  From Table 3, the shape of the reflective film 14 was crushed only for polystyrene with a Vicat softening temperature of 79 ° C, vinyl chloride with a Vicat softening temperature of 85 ° C, and polystyrene with a Vicat softening temperature of 88 ° C. For other resins, It was confirmed that there was no deformation. Therefore, regarding the reflection protection sheet 30 having the reflection structure layer 16 formed by laminating the optical structure layer 15 having the uneven shape and the reflection film 14, the material for forming the optical structure layer 15 is a thermosetting resin. Alternatively, it was confirmed that the thermoplastic resin required to have a Vicat softening temperature exceeding 88 ° C. In particular, it is presumed that deformation can be reliably prevented if the Vicat softening temperature is 98 ° C. or higher, and can be prevented if the Vicat softening temperature is 95 ° C. or higher.

DESCRIPTION OF SYMBOLS 1 Semiconductor power generation device main body 2 Front plate 3 Filling layer 4 Cell 10 Reflective protective sheet 11 Outer layer 12 Intermediate layer 13 Barrier layer 14 Reflective film 15 Optical structure layer 16 Reflective structure layer 17 Transmissive protective layer 20 Reflective protective sheet 26 Reflective structure layer 30 Reflective protection sheet 36 Reflective structure layer 100 Semiconductor power generator 101 Light source 102 Power meter 103 Blue plate glass 104 Glycerin

Claims (8)

A reflection protection sheet disposed on the back side of the semiconductor power generator main body that generates light by receiving light from the front surface,
At least a transmissive protective layer that transmits light emitted from the back surface of the semiconductor power generation device through the semiconductor power generation device;
A reflective structure layer that is disposed on the back side of the transmissive protective layer and reflects light transmitted through the transmissive protective layer toward the front side;
An outer layer disposed on the back side of the reflective structure layer and protecting the reflective structure layer;
The reflective structure layer is composed of an optical structure layer formed with a concavo-convex shape on the front surface or the back surface, and a reflective film laminated along the concavo-convex shape,
The reflection protective sheet, wherein the optical structure layer is formed of a thermosetting resin or a thermoplastic resin having a Vicat softening temperature of 95 ° C. or higher. The concavo-convex shape is formed on the front surface of the optical structure layer, and the water vapor transmission rate is 0 to 0.5 g / m ² between the reflective film and the transmissive protective layer laminated in the concavo-convex shape. The reflection protective sheet according to claim 1, further comprising a barrier layer. The concavo-convex shape is formed on the back surface of the optical structure layer, and a water vapor transmission rate of 0 to 0 is formed between the reflective film and the outer layer between the reflective film and the outer layer. The reflection protective sheet according to claim 1, further comprising a barrier layer of 0.5 g / m ² .   The reflection protective sheet according to claim 2, wherein the barrier layer comprises an inorganic oxide.   The concavo-convex shape is any one of a facet shape, a cone shape, a shape in which the top of the facet shape is rounded, a shape in which the top of the cone shape is rounded, or a reverse type of these shapes. The reflection protection sheet as described in any one of Claim 1 to 4.   The reflection protective sheet according to claim 5, wherein an apex angle of the uneven shape is set in a range of 111 ° to 137 °.   The reflection protective sheet according to claim 5 or 6, wherein an apex angle of the concavo-convex shape is set in a range of 120 ° to 135 °. A front plate for incident light;
A filling layer that transmits light transmitted through the front plate;
On the back side of the semiconductor power generation device main body, which is sealed inside the filling layer and includes a cell that receives light transmitted through the filling layer from a light receiving surface and converts it into electricity,
A semiconductor power generation device, wherein the reflection protection sheet according to any one of claims 1 to 7 is laminated.

Images