JP2008053510A - Rear surface protecting sheet for solar cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rear surface protecting sheet for a solar cell which has long-term durability against severe natural environment being excellent in heat resistance, weather resistance, water resistance, damp-proofing, wind pressure-proof property, hailstorm-proof property, chemical resistance, antifouling property, light reflective property, optical diffusivity, and other properties; and makes it possible to maintain output power and to extend life. <P>SOLUTION: In the rear surface protecting sheet for solar cell of a laminated body; an inside substrate layer, an intermediate barrier layer, and an outside substrate layer are sequentially laminated through an adhesion layer. The protecting sheet is composed of a base material film or a sheet of chlorine system resin or fluorine system resin, in which a polyvinylalcohol layer is formed at least in one side of the intermediate barrier layer. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention provides heat resistance, weather resistance, water resistance, moisture resistance, wind pressure resistance, drought resistance, chemical resistance, antifouling properties, light reflectivity, light diffusibility, etc. that can withstand harsh natural environments over a long period of time. It is related with the back surface protection sheet for solar cells which is excellent in these characteristics, and is capable of maintaining output and extending life.

  In recent years, various efforts have been made in various fields in order to suppress the emission of carbon dioxide while the interests of various countries in and out of the global warming issue have increased. It is said that the increase in the consumption of fossil fuels causes an increase in atmospheric carbon dioxide, the temperature of the earth rises due to the greenhouse effect, and is said to have a serious impact on the global environment. And while various energy alternatives to fossil fuels are being studied, solar cells, which are clean energy sources, are attracting attention, and expectations are increasing day by day.

  A solar cell constitutes the heart of a solar power generation system that directly converts sunlight energy into electricity, and is made of a semiconductor.

  Moreover, the structure does not use a single solar cell element as it is, but generally several to several tens of solar cell elements are wired in series or in parallel, and the elements are arranged for a long time (about 20 years). ), Various kinds of parsing for protection are performed and unitized.

  The unit incorporated in this package is called a solar cell module, and generally the surface that receives sunlight is covered with glass, and the gap is filled with a filler made of thermoplastic. The back surface is protected by a sheet of heat resistant, moisture resistant, water resistant, weather resistant plastic material or the like.

  Since these solar cell modules are used outdoors, in their configuration, material structure, etc., sufficient heat resistance, weather resistance, water resistance, moisture resistance, wind pressure resistance, light resistance, rainfall resistance, chemical resistance, Moisture resistance, antifouling properties, light reflectivity, light diffusibility, and other properties are required.

  In particular, the back protective sheet is required to have a weather resistance and a low water vapor transmission rate. This is because if the filler is peeled off or discolored due to the permeation of moisture or the wiring is corroded, the output of the module itself may be affected.

  Conventionally, as this back surface protection sheet for solar cells, there are many back surface protection sheets having a laminated structure in which an aluminum foil is sandwiched between white polyvinyl fluoride film (PVF) [manufactured by DuPont, trade name: Tedlar (registered trademark)]. It was used. However, this polyvinyl fluoride film has low mechanical strength and is softened by heat of a hot press at 140 to 150 ° C. applied at the time of producing a solar cell module.

  And the protrusion of a solar cell element electrode part penetrates a filler layer, further penetrates a polyvinyl fluoride film on the inner surface constituting the back surface protection sheet, and contacts with the aluminum foil in the back surface protection sheet, whereby the solar cell There are drawbacks such as short circuit between the element and aluminum foil, which adversely affects battery performance. Furthermore, it is expensive and is an obstacle in terms of reducing the cost of solar cell modules.

(1) Prior art 1
As a back protection sheet for solar cells, heat resistant, weather resistant, wind pressure resistant, light resistant, moisture proof, and other required functions were laminated, and an inexpensive heat resistant and weather resistant plastic film made of polyester resin was laminated. A back surface protection sheet having a configuration (for example, see Patent Document 1) is known.

  As shown in FIG. 4, the back surface protection sheet 100 is made of a polyester resin having an intrinsic viscosity of 0.6 (dl / g) or more and a cyclic trimer content of 0.5% by weight or less. An inorganic oxide thin film layer 102 is applied to one surface of a weatherproof, lightproof, and moistureproof plastic film 101. Then, another heat resistance, weather resistance, light resistance, and moisture proof plastic film 101 is laminated on the surface of the thin film layer 102 via an adhesive layer 103.

(2) Prior art 2
Excellent strength and weather resistance, heat resistance, water resistance, light resistance, wind pressure resistance, rain resistance, chemical resistance, moisture resistance, antifouling, light reflectivity, light diffusibility, design, etc. A back surface protection sheet for solar cell modules (see, for example, Patent Document 2) that is excellent in various characteristics and is safer at lower cost is also known.

  As shown in FIG. 5, the back protective sheet 200 has a heat seal resin layer 104 laminated on the front side surface of the base film 105. The rear side surface is provided with an inorganic oxide vapor deposition film 106, and a heat-resistant polypropylene resin film 107 is laminated on the surface of the vapor deposition film 106. Further, a weather-resistant black outermost layer 108 is provided.

(3) Prior art 3
In addition, it has a heat resistance, weather resistance, moisture proof and other required functions, and is a laminate having a structure in which an inexpensive heat resistance, weather resistance, water resistance, and light resistance plastic film made of polyester resin is laminated. The back surface protection sheet for solar cells (for example, refer patent document 3) is also known.

  This back surface protective sheet 300 has a heat resistance composed of a polyester resin having an intrinsic viscosity of 0.6 (dl / g) or more and a cyclic trimer content of 0.5% by weight or less, as shown in FIG. A weather-resistant, water-resistant, and light-resistant plastic film 109 is formed by laminating a front side surface and a back side surface of a metal foil 111 with an adhesive layer 110 interposed therebetween.

(4) Prior art 4
In addition, a back sheet for a solar cell cover material that is lightweight and has excellent water resistance and voltage resistance, is excellent in incident light reflectivity, is lightweight, inexpensive, and has excellent durability (for example, (See Patent Document 4).

  As shown in FIG. 7, this solar cell cover material backsheet 400 is resistant to hydrolysis via an adhesive layer 113 on one surface of a resin film 116 in which a base film 114 is coated with a metal oxide 115. A functional resin film 117 is laminated. Also, the other surface has a structure composed of a two-layer to three-layer resin film laminate in which a white resin film 112 is laminated via an adhesive layer 113. The base film 114 is made of a polyester film, the metal oxide 115 film is made of aluminum oxide, and the white pigment is made of titanium oxide.

Prior art documents are shown below.
JP 2002-134771 A JP 2003-152212 A JP 2002-134770 A Japanese Patent Laid-Open No. 2002-10078

(1) About Prior Art 1 In Prior Art 1, an inorganic oxide thin film layer is formed on one surface of a heat-resistant, weather-resistant, light-resistant, and moisture-proof plastic film. And, it is a laminate in which other heat resistance, weather resistance, light resistance and moisture proof plastic film are laminated on the surface of the thin film layer through an adhesive layer, and metal foil such as aluminum foil is not used. .

  For this reason, when manufacturing a solar cell, there are few bad effects, such as causing a short circuit between a solar cell element, aluminum foil, etc. which a protective sheet gets damaged, and a battery performance falls.

  However, the work process becomes complicated, such as forming an inorganic oxide thin film layer on a base film or the like. And there exists a problem that manufacturing cost rises.

  Further, the inorganic oxide thin film layer is easily damaged by bending or the like. And there exists a problem that gas barrier property falls remarkably. For this reason, there are defects such as lack of gas barrier resistance and hydrolysis resistance, poor dielectric breakdown strength and partial discharge voltage, and poor electrical insulation.

(2) About Prior Art 2 In Prior Art 2, a heat-sealable resin layer is laminated on the front side surface of the base film. And the thin film vapor deposition film layer which consists of inorganic oxides is formed in the back side surface. Furthermore, it is a laminate in which a heat-resistant polypropylene resin film is laminated on the surface of the deposited film layer.

  As described above, when a solar cell is manufactured because a metal foil such as an aluminum foil is not used for the back surface protection sheet, a short circuit occurs between the solar cell element and the aluminum foil, which is generated when the protection sheet is damaged. There is no adverse effect such as deterioration of battery performance.

  However, like the prior art 1, the work process is complicated and the work efficiency is poor, such as forming a thin film vapor deposition film layer made of an inorganic oxide on a base film or the like. And there exists a problem that manufacturing cost rises.

  In addition, a thin film deposited film layer made of an inorganic oxide is easily damaged by bending or the like. And there exists a problem that gas barrier property falls remarkably. For this reason, the dielectric breakdown strength and the partial discharge voltage are deteriorated. And there are drawbacks such as poor electrical insulation.

(3) Prior Art 3 A metal foil is sandwiched with a weather-resistant plastic film. For this reason, the light which has entered the back surface protective sheet can be reflected and returned to the solar cell element to improve the power conversion efficiency.

  In addition, because of the use of metal foil, etc., it has excellent strength, weather resistance, heat resistance, water resistance, moisture resistance, light resistance, chemical resistance, puncture resistance, impact resistance, and other robustness. Excellent in properties. Further, there are advantages such that the surface hardness is high, the surface is excellent in antifouling property to prevent the accumulation of dirt, dust and the like, and the protective ability is extremely high.

However, since metal foil is used, when manufacturing a solar cell, the protective sheet is damaged, causing a short circuit between the solar cell element and aluminum foil, etc., and adversely affecting battery performance. There is. Moreover, since metal foil is used, there exists a problem that material cost is high and sales cost becomes high.

  Furthermore, there are problems of lack of plasticity, lightness, light reflectivity, light diffusibility, design and the like, and inferior workability or workability.

(4) Prior Art 4 A white resin film in which an aluminum oxide film is provided on the back side of the resin film and titanium oxide is added to the front side is used without using a metal foil such as an aluminum foil on the back protective sheet. ing.

  For this reason, when manufacturing a solar cell, it seems that there are few bad influences, such as causing a short circuit between a solar cell element, aluminum foil, etc. which a protective sheet gets damaged, and a battery performance falls.

  However, as in the prior arts 1 and 2, the work process is complicated and the work efficiency is poor, such as forming a metal oxide film layer on the base film or the like. And there exists a problem that manufacturing cost rises.

  Furthermore, the metal oxide film layer is easily damaged by bending or the like. And there exists a problem that gas barrier property falls remarkably.

  Moreover, since the white resin film used for the protective sheet is added with titanium oxide or the like, there is a problem that the gas barrier property is remarkably lowered. And problems, such as an electrical insulation fall, arise.

  This invention is made | formed in view of the said conventional problem, and it aims at providing the back surface protection sheet for solar cells as follows.

  That is, the first object of the present invention is excellent in strength, weather resistance, heat resistance, moisture resistance, water resistance, light resistance, chemical resistance, puncture resistance, impact resistance, and other various fastness properties. Furthermore, it has a high surface hardness and excellent antifouling properties that prevent accumulation of dirt, dust, and the like. And the back surface for solar cells that has high protective ability, is excellent in plasticity, lightness, light reflectivity, light diffusibility, design, etc., and has good workability or workability, etc. It is to provide a protective sheet.

  In addition, the second object of the present invention is that when a solar cell is manufactured, the protective sheet is damaged, a short circuit is caused between the solar cell element and the aluminum foil, and the battery performance is deteriorated. It is providing the back surface protection sheet for solar cells which does not have.

  The third object of the present invention is to easily, efficiently and inexpensively produce a known coating machine or laminator without forming a vapor deposition film layer or the like without going through complicated work steps. It is providing the back surface protection sheet for solar cells with good power conversion efficiency.

  Moreover, the 4th objective of this invention is to provide the back surface protection sheet for solar cells which can be shape | molded and processed by a general purpose method, and also can be mass-produced.

In order to solve the above problems, first, the invention according to claim 1 of the present invention is:
A back protective sheet for solar cells of a laminate in which an inner surface base material layer, an intermediate barrier layer, and an outer surface base material layer are sequentially laminated via an adhesive layer,
A back protective sheet for a solar cell comprising a base film or sheet of a chlorine-based resin or a fluorine-based resin in which a polyvinyl alcohol layer is formed on at least one side surface of the intermediate barrier layer.

Next, the invention according to claim 2 of the present invention is
2. The back protective sheet for solar cell according to claim 1, wherein the base resin of the inner base layer and the outer base layer is made of the same resin as the base film or sheet of the intermediate barrier layer.

  The back surface protective sheet for solar cells of the present invention is a laminate in which an inner surface base material layer, an intermediate barrier layer, and an outer surface base material layer are sequentially laminated via an adhesive layer. For this reason, it can manufacture easily, efficiently, and cheaply with a well-known coating machine and a laminator machine, without passing through a complicated operation process.

  Moreover, since the polyvinyl alcohol layer is formed on at least one side surface of the base film or sheet of the chlorine-based resin or fluorine-based resin, the intermediate barrier layer has excellent gas barrier properties, particularly water vapor barrier properties, and is resistant to water. Excellent environmental resistance such as degradability and weather resistance.

  The same resin as the base film or sheet of the intermediate barrier layer is used for the inner base layer and the outer base layer. For this reason, dimensional stability is good, and high electrical insulation and good adhesiveness with a filler are obtained. And when unitizing using the back surface protection sheet for solar cells, the stable quality which a wiring does not bend or a battery does not shift | deviate is obtained. Furthermore, it can be molded by a general-purpose method, and large-scale solar cell modules can be mass-produced at low cost.

  Furthermore, when the solar cell is manufactured, the protective sheet is damaged, and there is no adverse effect on the battery performance due to short circuit, and there is no deterioration of various functions for a long period (about 20 years), and it can be used outdoors.

  The back surface protection sheet for solar cells of this invention is demonstrated in detail, referring drawings below along embodiment. 1 to 3 show an embodiment of the present invention.

  FIG. 1 is a schematic cross-sectional view showing a cross-section of one example illustrating the layer configuration of the back protective sheet for solar cells according to the present invention.

  First, as shown in FIG. 1, the back surface protection sheet 10 for solar cells according to one embodiment of the present invention has an inner surface base material layer 5 formed in an upper direction in which solar cell elements are provided. The intermediate barrier layer 3 is formed through the adhesive layer 4, and the outer surface base material layer 6 is formed through the adhesive layer 4.

  The intermediate barrier layer 3 has a polyvinyl alcohol (PVA) layer 2 formed on the upper surface of the base film or sheet 1. Although this polyvinyl alcohol (PVA) layer 2 is not shown in the drawing, it may be formed on the lower surface or both side surfaces of the base film or sheet 1 and is not particularly limited.

In addition, the base film or sheet 1 of the intermediate barrier layer 3 shown in FIG. 1 has at least one chlorine atom in the repeating unit of the molecular chain. For example, polyvinyl chloride resin (PVC) Polyvinylidene chloride resin (PVDC), ethylene tetrachloroethylene resin (ETCE), and other chlorinated resin films or sheets can be used. The thickness of the film or sheet of chlorinated resin is appropriately determined from the required insulating properties, etc., but a film of about 20 to 40 μm is used.

  Since the above-described resin has a chlorine atom in the molecule, the intramolecular interaction is very strong and the critical surface tension is very low. For this reason, molecular chains are not easily broken even under the influence of temperature, humidity, ultraviolet rays, and the like due to outdoor exposure, and deterioration with time is difficult.

  Chlorine resins have some water vapor and oxygen barrier properties. For this reason, a higher barrier property can be imparted by applying a barrier coat. In the present invention, a polyvinyl alcohol layer 2 is formed by applying polyvinyl alcohol as a barrier coat formed on the base film of the chlorine-based resin or the upper surface of the sheet 1.

  For the coating, a direct gravure roll method, a gravure roll method, a kiss coat method, a reverse roll method, a fountain method, a transfer roll method, or the like is used.

  Polyvinyl alcohol (PVA) has a large amount of hydroxyl groups in the molecule, so it is easy to build a network by hydrogen bonding between molecules, and high water vapor and oxygen barrier properties are formed on the coated surface. Is done.

  Further, by coating polyvinyl alcohol (PVA) on the upper surface of the chlorine-based resin base film or sheet 1, the chlorine-based resin base film or sheet having functionality having both weather resistance and barrier properties can be obtained. An intermediate barrier layer 3 is formed.

  Further, butanetetracarboxylic acid (BTC) is added as an additive to the polyvinyl alcohol (PVA) that forms the polyvinyl alcohol layer 3 formed on the upper surface of the base film or sheet 1 of the chlorine-based resin. Thus, it is possible to prevent a decrease in barrier properties at high humidity, which is also called a disadvantage of polyvinyl alcohol (PVA). The proportion of butanetetracarboxylic acid (BTC) added is preferably about 5 to 95%.

  Next, the base film or sheet forming the inner base layer 5 and the outer base layer 6 has excellent strength and weather resistance, heat resistance, water resistance, light resistance, wind pressure resistance, and yield resistance. Those having excellent fastness such as chemical resistance are preferred. In particular, it has excellent moisture resistance to prevent intrusion of moisture, oxygen, etc., has high surface hardness, and excellent antifouling property to prevent the accumulation of dirt and dust on the surface. Various resin films or sheets having characteristics such as high ability can be used.

  Examples of the various resin films or sheets include polyethylene resins, polypropylene resins, cyclic polyolefin resins, polystyrene resins, acrylonitrile-styrene copolymers (AS resins), acrylonitrile-butadiene-styrene copolymers. Polymer (ABS resin), polyvinyl chloride resin, fluorine resin, poly (meth) acrylic resin, polycarbonate resin, polyester resin such as polyethylene terephthalate or polyethylene naphthalate, Various polyamide resins such as nylon, polyimide resins, polyamide imide resins, polyaryl phthalate resins, silicone resins, polysulfone resins, polyphenylene sulfide resins, polyether sulfone resins, polyurethane resins , Acetal resin, Carlo - scan resins, other film or sheet of various resins - can be used and.

The various resin films or sheets may be, for example, one or more of the above-mentioned various resins, extrusion method, cast molding method, T-die method, inflation method, and other film forming methods. , A method of forming a film of various resins alone, a method of forming a multilayer coextrusion film using two or more kinds of resins, or a process of using two or more kinds of resins, Various resin films or sheets are produced by a method of forming a film by mixing before film formation. The film thickness of various resin films or sheets is preferably about 12 to 300 μm, more preferably about 50 to 200 μm.

  Among the various resin films or sheets described above, in the solar cell back surface protective sheet 10 of the present invention, it is used for the base film or sheet 1 of the chlorinated resin of the intermediate barrier layer 3. It is preferable to use a film or sheet 1 of a chlorine-based resin having a certain water vapor and oxygen barrier property, for example, a polyvinyl chloride resin, a polyvinylidene chloride resin, an ethylenetetrachloroethylene resin or the like.

  Flame retardants, antioxidants, ultraviolet absorbers, antistatic agents, etc. are added to the film or sheet 1 of chlorinated resin such as polyvinyl chloride resin, polyvinylidene chloride resin, ethylene tetrachloroethylene resin, etc. as necessary. You can also

  Moreover, the method of laminating | stacking the inner surface base material layer 5, the intermediate | middle barrier layer 3, and the outer surface base material layer 6 shown in FIG. 1 in order is a dry lamination method, a non-solvent dry lamination method, a hot-melt lamination method, an extrusion, for example. A known method such as a sandwich / extrusion lamination method using a lamination method can be appropriately used.

  The adhesive used in the dry lamination method is required to have an adhesive strength that deteriorates after long-term outdoor use, does not cause delamination, and the adhesive does not yellow due to solar heat. A laminate adhesive such as polyurethane, polyacrylic, polyester, epoxy, polyvinyl acetate, cellulose, or the like can be used.

  In order to prevent deterioration of the adhesive due to the long-term outdoor exposure, a deterioration inhibitor may be used. Examples of the deterioration preventing agent include additives such as isocyanate additives (TDI, XDI, etc.), carbodiimine, and epoxy.

  Moreover, the said additive can also be added with the butane tetracarboxylic acid (BTC) added to the polyvinyl alcohol of the polyvinyl alcohol layer 2 which forms the intermediate | middle barrier layer 3. FIG. And the barrier property of the polyvinyl alcohol layer 2 can be maintained without deteriorating for a long time. Furthermore, the quality of barrier property and weather resistance is satisfied at the same time, and the solar cell back surface protective sheet 10 of the present invention with higher functionality is produced.

  Next, FIG. 2 is a schematic cross-sectional view showing a cross-section of another example illustrating the layer configuration of the solar cell back surface protective sheet according to the present invention.

  First, as shown in FIG. 2, the back surface protection sheet 20 for solar cells according to another embodiment of the present invention has an inner surface base material layer 11 formed in an upper direction in which solar cell elements are provided. An intermediate barrier layer 9 is formed through the adhesive layer 4, and an outer surface base material layer 12 is formed through the adhesive layer 4.

  In the intermediate barrier layer 9, a polyvinyl alcohol (PVA) layer 8 is formed on the upper side surface of a fluororesin base film or sheet 7. The polyvinyl alcohol (PVA) layer 8 may be formed on the lower side surface or both side surfaces of the fluororesin base film or sheet 7 and is not particularly limited.

In addition, the fluororesin base film or sheet 7 of the intermediate barrier layer 9 shown in FIG. 2 has at least one fluorine atom in the repeating unit of the molecular chain. For example, polyvinyl fluoride (PVF), polyvinylidene fluoride (PVDF), ethylenetetrafluoroethylene (ETFE), and other fluororesins can be used. The thickness of the fluororesin base film or sheet 7 is determined as appropriate from the required insulating properties, but a thickness of about 20 to 40 μm is used.

  Since the above-described resin has a fluorine atom in the molecule, the intramolecular interaction is very strong and the critical surface tension is very low. For this reason, molecular chains are not easily broken even under the influence of temperature, humidity, ultraviolet rays, and the like due to outdoor exposure, and deterioration with time is difficult. Further, since the fluororesin has almost no barrier property, it is necessary to apply a barrier coat.

  As the barrier coat, a polyvinyl alcohol layer 8 is formed on the upper surface of the fluororesin base film or sheet 7 using polyvinyl alcohol.

  Furthermore, butanetetracarboxylic acid (BTC) is added as an additive to the polyvinyl alcohol (PVA) that forms the polyvinyl alcohol layer 8 formed on the upper surface of the fluororesin base film or sheet 7. Thus, it is possible to prevent a decrease in barrier properties at high humidity, which is also called a disadvantage of polyvinyl alcohol (PVA). The proportion of butanetetracarboxylic acid (BTC) added is preferably about 5 to 95%.

  Next, the base film or sheet forming the inner base layer 11 and the outer base layer 12 is excellent in strength and weather resistance, heat resistance, water resistance, light resistance, wind pressure resistance, and yield resistance. Those having excellent fastness such as chemical resistance are preferred. In particular, it has excellent moisture resistance to prevent intrusion of moisture, oxygen, etc., has high surface hardness, and excellent antifouling property to prevent the accumulation of dirt and dust on the surface. Various resin films or sheets having characteristics such as high ability can be used.

  Examples of the various resin films or sheets include polyethylene resins, polypropylene resins, cyclic polyolefin resins, polystyrene resins, acrylonitrile-styrene copolymers (AS resins), acrylonitrile-butadiene-styrene copolymers. Polymer (ABS resin), polyvinyl chloride resin, fluorine resin, poly (meth) acrylic resin, polycarbonate resin, polyester resin such as polyethylene terephthalate or polyethylene naphthalate, Various polyamide resins such as nylon, polyimide resins, polyamideimide resins, polyaryl phthalate resins, silicone resins, polysulfone resins, polyphenylene sulfide resins, polyethersulfone resins, polyurethane resins , Acetal resin, Carlo - scan resins, other film or sheet of various resins - can be used and.

  The various resin films or sheets may be, for example, one or more of the above-mentioned various resins, extrusion method, cast molding method, T-die method, inflation method, and other film forming methods. , A method of forming a film of various resins alone, a method of forming a multilayer coextrusion film using two or more kinds of resins, or a process of using two or more kinds of resins, Various resin films or sheets are produced by a method of forming a film by mixing before film formation. The film thickness of various resin films or sheets is preferably about 50 to 300 μm, more preferably about 50 to 200 μm.

  Among the various resin films or sheets described above, in the solar cell back surface protection sheet 20 of the present invention, for example, polyfluoride used for the base film or sheet 7 of the intermediate barrier layer 9. It is preferable to use a film or sheet 7 of vinyl, polyvinylidene fluoride, ethylenetetrafluoroethylene, other fluorine-based resin or weather-resistant polyethylene terephthalate resin.

  The fluororesin or weather resistant polyethylene terephthalate resin film or sheet 7 may be transparent, but a white film or sheet that reflects light may be used in consideration of the power generation efficiency of the solar cell element.

  The method for producing this white film is such that 5 to 20 parts by weight of a white pigment such as titanium oxide, silica, alumina, calcium carbonate or barium sulfate is used with respect to 100 parts by weight of the fluororesin or weather-resistant polyethylene terephthalate resin. It is prepared by kneading, melt extrusion by a T-die method, or an inflation method. Further, a foam layer may be provided for whitening.

  Depending on the color, the white pigment and carbon black may be used in combination. For amorphous solar cells, a black film or sheet kneaded with carbon black can also be used.

  In addition, the film or sheet 1 of polyvinyl fluoride, polyvinylidene fluoride, ethylene tetrafluoroethylene, other fluorine-based resin or weather-resistant polyethylene terephthalate resin may be provided with a flame retardant, an antioxidant, or an ultraviolet absorber as necessary. An agent, an antistatic agent, etc. can also be added.

  Furthermore, the method of sequentially laminating the inner surface base material layer 11, the intermediate barrier layer 9, and the outer surface base material layer 12 shown in FIG. 2 includes, for example, a dry lamination method, a non-solvent dry lamination method, a hot melt lamination method, and an extrusion. A known method such as a sandwich / extrusion lamination method using a lamination method can be appropriately used.

  The adhesive used in the dry lamination method is required to have an adhesive strength that deteriorates after long-term outdoor use, does not cause delamination, and the adhesive does not yellow due to solar heat. Then, polyurethane, polyacrylic, polyester, epoxy, polyvinyl acetate, cellulose, and other laminating adhesives can be used.

  In order to prevent deterioration of the adhesive due to the long-term outdoor exposure, a deterioration inhibitor may be used. Examples of the deterioration preventing agent include additives such as isocyanate additives (TDI, XDI, etc.), carbodiimine, and epoxy.

  Moreover, the said additive can also be added with the butane tetracarboxylic acid (BTC) added to the polyvinyl alcohol of the polyvinyl alcohol layer 8 which forms the intermediate | middle barrier layer 9. FIG. Furthermore, the barrier property of the polyvinyl alcohol layer 8 can be maintained without deteriorating for a long time. And the quality called barrier property and a weather resistance is satisfied simultaneously, and the more highly functional solar cell back surface protection sheet 20 of this invention is produced. And it is used as a member which comprises a solar cell module.

  Next, FIG. 3 is a schematic cross-sectional view of a solar cell module 80 unitized using the solar cell back surface protection sheets 10 and 20 according to the present invention described above.

The solar cell module 80 is formed of the upper transparent material 13, the fillers 14 and 15, the cell 30 constituted by the solar cell element 40 and the wiring 50, the solar cell back surface protection sheets 10 and 20, and the frame body 60. And the back surface protection sheets 10 and 20 for solar cells are the inner surface base material layers 5 and 11.
The side is used with the filler 14 side.

  The upper transparent material 13 has good light transmittance, excellent weather resistance over a long period of time (about 20 years), little decrease in light transmittance, dust and the like are less likely to adhere, and scratches are not easily scratched. And various functions such as extremely low water vapor transmission rate, and glass, acrylic resin, polycarbonate resin, silicone resin, fluorine resin and the like can be used.

  In addition, the fillers 14 and 15 have high transmittance of sunlight, no change in physical properties such as reduction in light transmittance due to long-term outdoor standing, etc., high insulation resistance, and corrosion of other materials. And has various functions such as no cracking of the resin due to a sudden change in outside air conditions, interfacial peeling, etc., and ethylene-vinyl acetate copolymer (EVA), polyvinyl butyral resin, silicone resin Vinyl chloride resin, polyurethane resin, etc. can be used.

  Further, the frame 60 is generally made of a mold material such as aluminum or an aluminum alloy.

  The solar cell module 80 is usually manufactured by sandwiching a cell 30 composed of the solar cell elements 40 previously wired 50 in a sandwich between two fillers 14 and 15 sheets, and then on one filler 15 sheet. Place the top transparent material 13. And the said back surface protection sheets 10 and 20 for solar cells are covered on the filler 14 sheet | seat of an other side so that the outer surface base material layers 6 and 12 surface may become an outer side.

  Furthermore, after preheating the whole under reduced pressure from both sides, hot pressing is performed to fuse and integrate the back protection sheets 10 and 20 for solar cells. And it fixes with the frame body 60 made from aminium, and the solar cell module 80 is produced.

  The solar cell back surface protective sheet of the present invention is an excellent invention that can be used in a wide range of fields, such as roof members for automobiles such as poultry houses and barns in summer and automobile covers, as well as being excellent as a back surface protective sheet for solar cells.

It is a schematic sectional drawing which shows the outline of the layer structure of one Example of the back surface protection sheet for solar cells of this invention. It is a schematic sectional drawing which shows the outline of the layer structure of other one Example of the back surface protection sheet for solar cells of this invention. It is explanatory drawing for demonstrating one Example of the solar cell module using the back surface protection sheet for solar cells of this invention. It is a schematic sectional drawing which shows the outline of the layer structure of the back surface protection sheet for solar cells used conventionally. It is a schematic sectional drawing which shows the outline of the layer structure of the back surface protection sheet for solar cells used conventionally. It is a schematic sectional drawing which shows the outline of the layer structure of the back surface protection sheet for solar cells used conventionally. It is a schematic sectional drawing which shows the outline of the layer structure of the back surface protection sheet for solar cells used conventionally.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Chlorine-based resin film or sheet 2 ... Polyvinyl alcohol layer 3 ... Intermediate barrier layer 4 ... Adhesive layer 5 ... Inner surface base material layer 6 ... Outer surface base material layer 7 ... Fluorine resin film or sheet 8 DESCRIPTION OF SYMBOLS ... Polyvinyl alcohol layer 9 ... Intermediate | middle barrier layer 10 ... Back surface protection sheet for solar cells 11 ... Inner surface base material layer 12 ... Outer surface base material layer 13 ... Upper transparent material 14 ... Filler 15 ... Filler 20 ... Surface protection for solar cells Sheet 30 ... Cell 40 ... Solar cell element 50 ... Wiring 60 ... Formwork 80 ... Solar cell module

Claims (2)

A back protective sheet for solar cells of a laminate in which an inner surface base material layer, an intermediate barrier layer, and an outer surface base material layer are sequentially laminated via an adhesive layer,
A back protective sheet for solar cells, comprising a base film or sheet of a chlorine-based resin or a fluorine-based resin in which a polyvinyl alcohol layer is formed on at least one side surface of the intermediate barrier layer.   The back surface protection sheet for solar cells according to claim 1, wherein the base material resin of the inner surface base material layer and the outer surface base material layer is made of the same resin as the base film or sheet of the intermediate barrier layer.

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