JP2012089631A - Protective sheet for solar cells, manufacturing method of the same, and solar cell module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a protective sheet for solar cells which is excellent in the adhesiveness of a sealing material and suppresses warpage occurred in a solar cell module, a manufacturing method of the protective sheet, and a solar cell module which is excellent in the adhesiveness between the sealing material and the protective sheet and suppresses the warpage.SOLUTION: A protective sheet 1 for solar cells includes a base material 11 and a thermoplastic resin layer 12 laminated on at least one side of the base material 11. The density of the thermoplastic resin layer 12 is 875 to 920 kg/m, and the thermoplastic resin layer 12 is mainly composed of an olefin-based resin having the melting calorie ΔH which is equal to or less than 100.0 J/g and is measured by a differential scanning calorimeter.

Description

  The present invention relates to a solar cell protective sheet used as a surface protective sheet or a back surface protective sheet of a solar cell module, a method for producing the same, and a solar cell module using the solar cell protective sheet.

  Solar cell modules that convert solar light energy into electrical energy are attracting attention as a clean energy source that can generate electricity without emitting carbon dioxide in response to environmental problems such as air pollution and global warming.

  Generally, a solar cell module is composed of a solar cell made of crystalline silicon, amorphous silicon, or the like that performs photoelectric conversion, a sealing material (filling layer) made of an electrical insulator that seals the solar cell, and the surface of the sealing material. It is comprised from the surface protection sheet (front sheet) laminated | stacked on (light-receiving surface) and the back surface protection sheet (back sheet) laminated | stacked on the back surface of the sealing material. In order to provide the solar module with the weather resistance and durability that can withstand long-term use outdoors and indoors, the solar cells and sealing material are protected from wind, rain, moisture, dust, mechanical shock, etc. It is necessary to keep the inside of the battery module sealed from the outside air. For this reason, the protection sheet for solar cells is required to have moisture resistance and weather resistance that can withstand long-term use.

  Patent Document 1 discloses a solar cell module in which a silicon power generation element is sealed with a sealing material made of an ethylene-vinyl acetate copolymer sheet, and a back sheet is laminated on the back surface of the sealing material. As a back sheet, a sheet in which a fluorine-based plastic film having weather resistance (Tedlar film manufactured by DuPont) is bonded to one side or both sides of a layer that prevents water vapor permeation, such as metal, is disclosed. This back sheet is heat-bonded to the sealing material.

  However, the conventional back sheet as disclosed in Patent Document 1 has a problem in that the back sheet peels off from the sealing material and water vapor enters the sealing material because of low adhesion to the sealing material. Thus, it has been proposed to improve the adhesion (adhesion) to the above-mentioned sealing material by providing a heat-fusible layer on the back sheet.

  Specifically, Patent Document 2 discloses a back sheet laminated on the back surface of a filler in a solar cell module using an ethylene-vinyl acetate copolymer as a filler, and includes an epoxy compound and / or a silane compound. A heat-fusible layer made of a heat-fusible resin composed mainly of a graft-modified ethylene- (meth) acrylic acid ester copolymer, ethylene-vinyl acetate copolymer, or a mixture thereof is laminated on a heat-resistant film. Has been disclosed.

Japanese Patent Laid-Open No. 6-177412 JP 2008-108947 A

  In patent document 2, when manufacturing a back sheet, a heat-fusible layer is laminated | stacked with an extrusion coating method with respect to a heat resistant film. Such a method of forming a heat-fusible layer has high productivity, but has a problem that shrinkage occurs due to cooling of the heat-fusible layer and curls occur in the width direction or the flow direction of the roll. If the solar cell module is warped along with the curl of the back sheet, not only will the malfunction occur when the solar cell module is installed, but the solar cell module may be damaged.

  This invention is made | formed in view of such an actual condition, While being excellent in the adhesiveness with respect to the sealing material of a solar cell module, the protective sheet for solar cells which can suppress the curvature which arises in a solar cell module, and its It is an object of the present invention to provide a solar cell module that is excellent in the manufacturing method and the adhesiveness between the sealing material and the protective sheet and in which the warpage is suppressed.

In order to achieve the above object, first, the present invention provides a solar cell protective sheet comprising a base material and a thermoplastic resin layer laminated on at least one surface of the base material, The plastic resin layer has a density of 875 to 920 g / m ³ and a main component of an olefin resin having a heat of fusion ΔH obtained by a differential scanning calorimeter of 100.0 J / g or less. A protective sheet is provided (Invention 1).

  In the solar cell protective sheet according to the above invention (Invention 1), the thermoplastic resin layer is mainly composed of an olefin resin, so that the solar cell module has excellent adhesion to the sealing material. In addition, due to the low density and low crystallinity of the olefin resin that satisfies the above requirements, the shrinkage rate of the thermoplastic resin layer is small, so that the curl amount of the protective sheet for solar cells is small. The solar cell module can be prevented from warping due to the curling of the protective sheet.

  In the said invention (invention 1), it is preferable that the said olefin resin contains 60-100 mass% of ethylene as a monomer unit (invention 2).

  In the said invention (invention 1 and 2), it is preferable that the said thermoplastic resin layer is formed by extrusion coating (invention 3).

  In the said invention (invention 1-3), it is preferable that the said thermoplastic resin layer is a single layer (invention 4).

  In the said invention (invention 1-4), it is preferable that the said thermoplastic resin layer is a layer adhere | attached with the sealing material which comprises a solar cell module (invention 5).

2ndly this invention is a manufacturing method of the protection sheet for solar cells provided with the base material and the thermoplastic resin layer laminated | stacked on the at least one surface of the said base material, Comprising: A density is 880-915 g / m. ^{3. A} thermoplastic resin composition mainly composed of an olefin resin having a heat of fusion ΔH of 100.0 J / g or less obtained by a differential scanning calorimeter is extrusion coated on at least one surface of the substrate. Then, the manufacturing method of the protection sheet for solar cells characterized by forming the said thermoplastic resin layer is provided (invention 6).

  3rdly this invention is a solar cell module provided with the photovoltaic cell, the sealing material which seals the said photovoltaic cell, and the protective sheet laminated | stacked on the said sealing material, Comprising: The said protective sheet is And a solar cell module comprising the protective sheet for solar cells (invention 5), wherein the protective sheet is bonded to the sealing material via the thermoplastic resin layer (invention 7). ).

  The solar cell protective sheet according to the present invention is excellent in adhesion to the sealing material of the solar cell module, and can suppress warping that occurs in the solar cell module because the curl amount is small. Moreover, according to the manufacturing method of the protection sheet for solar cells which concerns on this invention, the protection sheet for solar cells which has the above outstanding effects is obtained. Furthermore, in the solar cell module according to the present invention, the adhesiveness between the sealing material and the protective sheet is excellent, and warpage due to curling of the protective sheet is suppressed.

It is a schematic sectional drawing of the protection sheet for solar cells which concerns on one Embodiment of this invention. It is a schematic sectional drawing of the protection sheet for solar cells which concerns on other embodiment of this invention. It is a schematic sectional drawing of the protection sheet for solar cells which concerns on other embodiment of this invention. It is a schematic sectional drawing of the protection sheet for solar cells which concerns on other embodiment of this invention. It is a schematic sectional drawing of the solar cell module which concerns on one Embodiment of this invention. It is a schematic sectional drawing of the solar cell module which concerns on other embodiment of this invention.

Hereinafter, embodiments of the present invention will be described.
[Protective sheet for solar cell]
As shown in FIG. 1, the solar cell protective sheet 1 according to this embodiment includes a base material 11 and a thermoplastic resin layer 12 laminated on one surface of the base material 11 (upper surface in FIG. 1). I have. This solar cell protective sheet 1 is used as a surface protective sheet (front sheet) or a back surface protective sheet (back sheet) of a solar cell module.

  As the base material 11, any material that has electrical insulation and can be laminated with the thermoplastic resin layer 12 may be used. Usually, a material mainly composed of a resin film is used.

  As a resin film used for the base material 11, what is generally used as the resin film in the solar cell module backsheet is selected. Examples of such resin films include polyolefin resins such as polyethylene and polypropylene, polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate, polyamide resins such as nylon (trade name), polycarbonate resins, and polystyrene. A film or sheet made of a resin such as a resin, a polyacrylonitrile resin, a polyvinyl chloride resin, a polyvinyl acetal resin, a polyvinyl butyral resin, or a fluorine resin is used. Among these resin films, a film made of a polyester resin is preferable, and a PET film is particularly preferable.

  In addition, the said resin film may contain various additives, such as a pigment, a ultraviolet absorber, a ultraviolet stabilizer, a flame retardant, a plasticizer, an antistatic agent, a lubricant, and an antiblocking agent, as needed. Examples of the pigment include titanium dioxide and carbon black. Examples of the ultraviolet absorber include benzophenone series, benzotriazole series, oxalic acid anilide series, cyanoacrylate series, and triazine series.

  Here, when using the solar cell protective sheet 1 according to this embodiment as a back sheet of a solar cell module, the resin film preferably contains a pigment that reflects visible light. Moreover, when using the solar cell protective sheet 1 according to the present embodiment as a front sheet of a solar cell module, it is preferable not to contain a pigment that reduces the light transmittance in the visible light region, thereby improving the weather resistance. It is more preferable to contain an ultraviolet absorber for the purpose.

  The surface of the resin film on which the thermoplastic resin layer 12 is laminated is preferably subjected to surface treatment such as corona treatment, plasma treatment, and primer treatment in order to improve adhesion to the thermoplastic resin layer 12. .

  The thickness of the base material 11 is appropriately set based on the electrical insulation required for the solar cell module. For example, when the substrate 11 is a resin film, the thickness is preferably 10 to 300 μm. More specifically, when the base material 11 is a PET film, the thickness is preferably 10 to 300 μm, more preferably 20 to 250 μm, from the viewpoint of electrical insulation and weight reduction. It is especially preferable that it is -200 micrometers.

Although the thermoplastic resin layer 12 in this embodiment is for adhere | attaching the solar cell protective sheet 1 on the sealing material of a solar cell module, this invention is not limited to this. The thermoplastic resin layer 12 in this embodiment has a density of 875 to 920 g / m ³ , preferably 880 to 915 g / m ³ , and a heat of fusion ΔH obtained by a differential scanning calorimeter is preferably 100.0 J / g or less, preferably Is mainly composed of an olefin resin of 95 J / g or less. The density is a value obtained by measurement according to JIS K7112. Here, the lower limit of the heat of fusion ΔH is naturally determined by the relationship with the density and the skeleton of each resin, but is theoretically preferably 0.

  The thermoplastic resin layer 12 mainly composed of an olefin resin has high adhesiveness to the sealing material of the solar cell module due to the excellent heat-sealing action of the olefin resin. Further, as described above, an olefin resin having a low density or an ultra-low density and a low heat of fusion, that is, low crystallinity, has a small shrinkage rate even when cooled from a heated and melted state. Therefore, by using the olefin-based resin as a main component of the thermoplastic resin layer 12, even when the thermoplastic resin layer 12 is formed on the base material 11 by extrusion coating, stress acting toward the base material 11 is hardly generated. Therefore, the curl amount of the protective sheet 1 for solar cells is small. Thereby, it can suppress that curvature arises in a solar cell module resulting from the curl of the protection sheet 1 for solar cells. Specifically, when the solar cell protective sheet 1 is cut into a 300 mm × 300 mm square and placed on a horizontal table, the warpage of the solar cell module is suppressed when the vertical curl amount is 20 mm or less. However, according to the solar cell protective sheet 1 including the thermoplastic resin layer 12 mainly composed of the olefin-based resin, the curl amount can be suppressed to 20 mm or less.

When the density of the olefin-based resin is less than 875 g / m ³ , the thermoplastic resin layer 12 is tacked, blocking occurs in the wound solar cell protective sheet 1, and the solar cell protective sheet 1 is blocked. Or the wound solar cell protective sheet 1 cannot be unwound. On the other hand, when the density of the olefin resin exceeds 920 g / m ³ , the curl amount of the solar cell protective sheet 1 increases. Further, even when the heat of fusion ΔH of the olefin resin exceeds 100.0 J / g, the curl amount of the solar cell protective sheet 1 increases. When the amount of curl of the solar cell protective sheet 1 is increased, a large warp is generated in the obtained solar cell module, and a problem occurs when the solar cell module is installed, or the solar cell module is damaged.

  The melt flow rate (MFR) of the olefin resin is preferably 1 to 20 g / 10 min, and particularly preferably 2 to 10 g / 10 min. When the MFR of the olefin resin is within the above range, the thermoplastic resin layer 12 can be formed by extrusion coating.

As the olefin resin, for example, low density polyethylene (LDPE, density: 910 g / cm ³ or more and less than 915 g / cm ^3), very low density polyethylene (VLDPE, density: 880 g / cm ³ or more and less than 910 g / cm ³⁾ Such as polyethylene resin, polypropylene resin (PP), polyethylene-polypropylene polymer, olefin elastomer (TPO), cycloolefin resin, ethylene-vinyl acetate copolymer (EVA), ethylene-vinyl acetate-maleic anhydride copolymer , Ethylene- (meth) acrylic acid copolymer, ethylene-butyl acrylate copolymer (EBA), ethylene- (meth) acrylic acid ester-maleic anhydride copolymer, and the like. Two or more kinds can be mixed and used. In the present specification, (meth) acrylic acid means both acrylic acid and methacrylic acid. The same applies to other similar terms.

  Among the olefin-based resins, a polyethylene-based resin containing 60 to 100% by mass, particularly 70 to 99.5% by mass of ethylene as a monomer unit is preferable, and further, ethylene as a monomer unit is preferably 60 to 100% by mass. %, In particular 70 to 99.5% by mass of ultra-low density polyethylene is preferred. Such a polyethylene resin has excellent processability and has a high affinity for a sealing material for a solar cell module, particularly a sealing material made of an ethylene-vinyl acetate copolymer, which is the same ethylene type, and has a very high adhesiveness. Excellent.

  Even if the thermoplastic resin layer 12 in the present embodiment is a single layer, curling of the solar cell protective sheet 1 can be suppressed, so that it is preferable that the thermoplastic resin layer 12 is also a single layer in terms of material cost and manufacturing cost.

  The thermoplastic resin layer 12 should just contain the olefin resin mentioned above as a main component, Specifically, it is preferable to contain 60 mass% or more of the said olefin resin, and to contain 80 mass% or more. Is more preferable, and it is particularly preferable to contain 90% by mass or more. Naturally, the thermoplastic resin layer 12 may be made of only an olefin resin.

  In addition to the olefin-based resin, the thermoplastic resin layer 12 may include various additives such as pigments, ultraviolet absorbers, ultraviolet stabilizers, flame retardants, plasticizers, antistatic agents, lubricants, and antiblocking agents as necessary. May be included.

  The thickness of the thermoplastic resin layer 12 is not particularly limited as long as it exhibits desired adhesion to the adherend and does not impair the effects of the present invention. Specifically, the thickness of the thermoplastic resin layer 12 is preferably 1 to 200 μm, more preferably 10 to 180 μm, and 50 to 150 μm from the viewpoint of electrical insulation and weight reduction. Is more preferable, and it is especially preferable that it is 80-120 micrometers.

  Here, as shown in FIG. 2, it is preferable that a fluororesin layer 13 is provided on the surface of the base material 11 on which the thermoplastic resin layer 12 is not laminated (the lower surface in FIG. 2). By providing the fluororesin layer 13 in this manner, the weather resistance and chemical resistance of the solar cell protective sheet 1 are improved. In addition, when the base material 11 consists of a resin film, in order to improve the adhesiveness with the fluororesin layer 13, the surface by which the fluororesin layer 13 of the said resin film is laminated | stacked is a corona treatment, a plasma treatment, a primer. Surface treatment such as treatment is preferably performed.

  The fluororesin layer 13 is not particularly limited as long as it contains fluorine. For example, the fluororesin layer 13 is constituted by a sheet having a fluorine-containing resin (fluorine-containing resin sheet), a coating film formed by applying a paint containing the fluorine-containing resin, or the like. Is done. Among these, from the viewpoint of making the fluororesin layer 13 thinner in order to reduce the weight of the solar cell protective sheet 1, a coating film formed by applying a paint having a fluorine-containing resin is preferable.

  As the fluorine-containing resin sheet, for example, a sheet obtained by processing a resin mainly composed of polyvinyl fluoride (PVF), ethylene chlorotrifluoroethylene (ECTFE), or ethylene tetrafluoroethylene (ETFE) is used. Examples of the resin mainly composed of PVF include E.I. I. “Tedlar” (trade name) manufactured by du Pont de Nemours and Company. Examples of the resin mainly composed of ECTFE include “Halar” (trade name) manufactured by Solvay Solexis. Examples of the resin mainly composed of ETFE include “Fluon” (trade name) manufactured by Asahi Glass Co., Ltd.

  When the fluororesin layer 13 is a fluorine-containing resin sheet, the fluororesin layer 13 is laminated on the base material 11 via an adhesive layer. The adhesive layer is composed of an adhesive having adhesiveness to the substrate 11 and the fluorine-containing resin sheet. Examples of such adhesives include acrylic adhesives, polyurethane adhesives, epoxy adhesives, polyester adhesives, and polyester polyurethane adhesives. These adhesives may be used individually by 1 type, and may be used in combination of 2 or more type.

  On the other hand, when the fluororesin layer 13 is a coating film formed by applying a paint having a fluorine-containing resin, the paint containing the fluorine-containing resin is usually applied directly to the substrate 11 without using an adhesive layer. The fluororesin layer 13 is laminated on the base material 11.

  The paint containing the fluorine-containing resin is not particularly limited as long as it is dissolved in a solvent or dispersed in water and can be applied.

  The fluorine-containing resin contained in the paint is not particularly limited as long as it does not impair the effects of the present invention and contains fluorine. However, it is usually soluble in a paint solvent (organic solvent or water) and can be crosslinked. Things are used. As the fluorine-containing resin, it is preferable to use a fluoroolefin resin having a curable functional group. Examples of such a fluoroolefin resin include tetrafluoroethylene (TFE), isobutylene, vinylidene fluoride (VdF), a copolymer comprising hydroxybutyl vinyl ether and other monomers, or TFE, VdF, hydroxybutyl vinyl ether and other Examples thereof include a copolymer composed of monomers.

  Specific examples of fluoroolefin resins include “LUMIFLON” (trade name) manufactured by Asahi Glass Co., “CEFRAL COAT” (trade name) manufactured by Central Glass Co., Ltd., and “FLUONATE” (trade name) manufactured by DIC Corporation. Polymers mainly composed of fluoroethylene (CTFE), polymers mainly composed of tetrafluoroethylene (TFE) such as “ZEFFLE” (trade name) manufactured by Daikin Industries, Ltd .; I. Polymers having a fluoroalkyl group, such as “Zonyl” (trade name) manufactured by du Pont de Nemours and Company, “Unidyne” (trade name) manufactured by Daikin Industries, Ltd. Can be mentioned. Among these, from the viewpoint of weather resistance, pigment dispersibility, and the like, a polymer containing CTFE as a main component and a polymer containing TFE as a main component are preferable, and “LUMIFLON” and “ZEFFLE” are particularly preferable.

  “LUMIFLON” is an amorphous resin containing CTFE and several types of specific alkyl vinyl ethers (VE) or hydroxyalkyl vinyl ethers as main structural units. A resin having a monomer unit of hydroxyalkyl vinyl ether such as “LUMIFLON” is preferable because it is excellent in solvent solubility, cross-linking reactivity, substrate adhesion, pigment dispersibility, hardness and flexibility.

  “ZEFFLE” is a copolymer of TFE and organic solvent-soluble hydrocarbon olefins. Among them, those containing hydrocarbon olefins with highly reactive hydroxyl groups are solvent-soluble, crosslinking reactivity, and substrate adhesion. And pigment dispersibility is preferable.

  Examples of the copolymerizable monomer that forms the fluorine-containing resin contained in the paint include vinyl acetate, vinyl propionate, butyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl caproate, vinyl versatate, vinyl laurate, Vinyl esters of carboxylic acids such as vinyl stearate, vinyl cyclohexyl carboxylate and vinyl benzoate, alkyl vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, butyl vinyl ether and cyclohexyl vinyl ether, CTFE, vinyl fluoride (VF), VdF and fluorine And fluorine-containing monomers such as fluorinated vinyl ethers.

  Further, the fluorine-containing resin contained in the paint may be a resin composed of one or more monomers or a terpolymer. Examples of the terpolymer include “Dyneon THV” (trade name) manufactured by 3M Company, which is a terpolymer of VdF, TFE, and hexafluoropropylene. Such a terpolymer is preferable because it can impart the properties of each monomer to the resin. In particular, “Dyneon THV” is preferable because it can be produced at a relatively low temperature, can be bonded to an elastomer or a hydrocarbon-based plastic, and is excellent in flexibility and optical transparency.

  The coating material may contain a crosslinking agent, a curing catalyst, a solvent and the like in addition to the fluorine-containing resin described above, and may further contain an inorganic compound such as a pigment and a filler, if necessary.

  The solvent contained in the paint is not particularly limited as long as it does not impair the effects of the present invention. For example, methyl ethyl ketone (MEK), cyclohexanone, acetone, methyl isobutyl ketone (MIBK), toluene, xylene, methanol, isopropanol, ethanol , Heptane, ethyl acetate, isopropyl acetate, n-butyl acetate or n-butyl alcohol, and a solvent containing any one or more organic solvents is preferably used.

  The pigment or filler contained in the paint is not particularly limited as long as it does not impair the effects of the present invention. For example, titanium dioxide, carbon black, perylene pigment, mica, polyamide powder, boron nitride, zinc oxide, aluminum oxide Silica, ultraviolet absorbers, preservatives, desiccants and the like are used. Specifically, as pigments and fillers, E.I. is rutile titanium dioxide treated with silicon oxide in order to impart durability. I. “Ti-Pure R105” (trade name) manufactured by du Pont de Nemours and Company, and “CAB-O-SIL TS” manufactured by Cabot, which is a hydrophobic silica in which hydroxyl groups on the silica surface are modified by surface treatment of dimethyl silicone. “720” (trade name) is preferably used.

  The coating film of the fluorine-containing resin is preferably cured with a crosslinking agent in order to improve weather resistance and scratch resistance. The crosslinking agent is not particularly limited as long as the effects of the present invention are not impaired, and metal chelates, silanes, isocyanates, or melamines are preferably used. Assuming that the solar cell protective sheet 1 is used outdoors for a long period of time, aliphatic isocyanates are preferable as the crosslinking agent from the viewpoint of weather resistance.

  The curing catalyst contained in the coating is not particularly limited as long as it does not impair the effects of the present invention, and examples thereof include tin dibutyldilaurate for promoting the crosslinking between the fluorine-containing resin and isocyanate.

  The composition of the coating is not particularly limited as long as the effects of the present invention are not impaired. For example, the coating composition is prepared by mixing a fluorine-containing resin, a pigment, a crosslinking agent, a solvent, and a catalyst. As composition ratio, when the whole coating material is 100 mass%, it is preferable that the content rate of fluorine-containing resin is 3-80 mass%, especially 25-50 mass%, and the content rate of a pigment is 5-60 mass%. %, Particularly 10 to 30% by mass, and the solvent content is preferably 20 to 80% by mass, and particularly preferably 25 to 65% by mass.

As a method of applying the paint to the substrate 11, a known method is used, for example,
What is necessary is just to apply | coat the fluororesin layer 13 obtained by bar coating method, knife coating method, roll coating method, blade coating method, die coating method, gravure coating method, etc. so that it may become desired thickness.

  The drying temperature of the coating material applied to the substrate 11 may be any temperature that does not impair the effects of the present invention, and is preferably in the range of 50 to 130 ° C. from the viewpoint of reducing the influence on the substrate 11.

  The thickness of the fluororesin layer 13 is set in consideration of weather resistance, chemical resistance, weight reduction, and the like, and is preferably 5 to 50 μm, and particularly preferably 10 to 30 μm.

  Further, a vapor deposition layer 14 may be provided between the base material 11 and the fluororesin layer 13 on the surface of the base material 11 on which the thermoplastic resin layer 12 is not laminated, as shown in FIG. 4, the metal sheet 16 may be laminated via the adhesive layer 15, and the surface of the vapor deposition layer 14 or the metal sheet 16 (the lower surface in FIGS. 3 and 4) is the same as described above. A fluororesin layer 13 may be provided. Thus, by providing the vapor deposition layer 14 or the metal sheet 16, the moisture-proof property and weather resistance of the protection sheet 1 for solar cells can be improved.

  In addition, when the base material 11 consists of a resin film, in order to improve the adhesiveness with the vapor deposition layer 14 or the contact bonding layer 15, the surface by which the vapor deposition layer 14 or the contact bonding layer 15 of the said resin film is laminated | stacked is a corona. Surface treatment such as treatment, plasma treatment, and primer treatment is preferably performed.

  The vapor deposition layer 14 is comprised from inorganic materials, such as a metal or a semimetal, or an oxide, nitride, silicide, etc. of a metal or a semimetal, By being comprised from such material, the base material 11 (protective sheet for solar cells) It is possible to impart moisture resistance (water vapor barrier property) and weather resistance to 1).

  Examples of the vapor deposition method for forming the vapor deposition layer 14 include chemical vapor deposition such as plasma chemical vapor deposition, thermal chemical vapor deposition, and photochemical vapor deposition, or vacuum vapor deposition, sputtering, and ion plating. A physical vapor phase method such as a method is used. Among these methods, the sputtering method is preferable in consideration of operability and controllability of the layer thickness.

  Examples of the metal used as the raw material of the vapor deposition layer 14 include aluminum (Al), magnesium (Mg), calcium (Ca), potassium (K), tin (Sn), sodium rim (Na), titanium (Ti), and lead. (Pb), zirconium (Zr), yttrium (Y) and the like. Examples of the semimetal include silicon (Si) and boron (B). Examples of these metal or metalloid oxides, nitrides, and oxynitrides include aluminum oxide, tin oxide, silicon oxide, silicon nitride, silicon oxynitride, and aluminum oxynitride.

  The vapor deposition layer 14 may be made of one kind of inorganic material or may be made of a plurality of kinds of inorganic materials. When the vapor deposition layer 14 is made of a plurality of types of inorganic materials, it may be a vapor deposition layer having a laminated structure in which the layers made of the respective inorganic materials are sequentially vapor deposited, or may be a vapor deposition layer in which a plurality of types of inorganic materials are vapor deposited simultaneously. May be.

  The thickness of the vapor deposition layer 14 is appropriately set in consideration of the water vapor barrier property, and is changed depending on the type of inorganic material used, vapor deposition density, and the like. Usually, it is preferable that the thickness of the vapor deposition layer 14 is 5-200 nm, and it is especially preferable that it is 10-100 nm.

  On the other hand, the metal sheet 16 can also provide moisture resistance (water vapor barrier property) and weather resistance to the base material 11 (protective sheet 1 for solar cells), similarly to the vapor deposition layer 14. The material of the metal sheet 16 is not particularly limited as long as it has such a function, and examples thereof include metals such as aluminum and aluminum alloys such as aluminum-iron alloys.

  The thickness of the metal sheet 16 is not particularly limited as long as the effects of the present invention are not impaired, but from the viewpoint of low pinhole occurrence frequency, high mechanical strength, high water vapor barrier properties, and weight reduction, etc. It is preferable that it is 5-100 micrometers, and it is especially preferable that it is 10-50 micrometers.

  The adhesive layer 15 is composed of an adhesive having adhesiveness to the base material 11 and the metal sheet 16. As the adhesive constituting the adhesive layer 15, for example, an acrylic adhesive, a polyurethane adhesive, an epoxy adhesive, a polyester adhesive, a polyester polyurethane adhesive, or the like is used. These adhesives may be used individually by 1 type, and may be used in combination of 2 or more type.

  Although the thickness of the contact bonding layer 15 is not specifically limited unless the effect of this invention is impaired, Usually, it is preferable that it is 1-20 micrometers, and it is especially preferable that it is 3-10 micrometers.

  In addition, in the above embodiment, although the solar cell protective sheet 1 in which the thermoplastic resin layer 12 was laminated on one surface of the base material 11 was illustrated, the solar cell protective sheet of the present invention is not limited thereto. The thermoplastic resin layer may also be laminated on the other surface of the substrate 11 (the surface opposite to the one surface).

[Method for producing protective sheet for solar cell]
In order to manufacture the solar cell protective sheet 1 according to the present embodiment (as an example, the solar cell protective sheet 1 shown in FIG. 1), the thermoplastic resin composition constituting the thermoplastic resin layer 12 is used as the base material 11. It is preferable to form the thermoplastic resin layer 12 on the substrate 11 by extrusion coating on at least one surface of the substrate 11. According to such an extrusion coating method, the protection sheet 1 for solar cells can be manufactured with high productivity and at low cost. Moreover, since it is not necessary to separately provide an adhesive layer for adhering the solar cell protective sheet 1 to the sealing material of the solar cell module, it is possible to prevent deterioration over time due to decomposition of the adhesive or the like.

  Specifically, using a T-die extruder or a T-die film forming machine, the resin composition for forming the thermoplastic resin layer 12 is melted and kneaded, and the substrate 11 is moved at a constant speed. Then, the molten resin composition is extruded and laminated on one surface of the base material 11 to form the thermoplastic resin layer 12 on the base material 11, thereby obtaining the solar cell protective sheet 1.

  In addition, as shown in FIGS. 2-4, when the other layer is formed in the base material 11, it is a thermoplastic resin layer in the surface of the side in which the said other layer of the base material 11 is not formed. 12 may be formed.

  The temperature at which the resin composition forming the thermoplastic resin layer 12 is melted is such that the base material 11 is not deformed by the temperature (heat) of the molten resin composition, and is preferably 80 to 350 ° C., and preferably 150 to 300 It is particularly preferable that the temperature is C.

  Moreover, the discharge amount from the T-die extruder (T-die film forming machine) of the resin composition forming the thermoplastic resin layer 12 depends on the thickness of the target thermoplastic resin layer 12 and the moving speed of the substrate 11. Are adjusted accordingly.

  The base material 11 is moved (conveyed) in the longitudinal direction at a constant speed by, for example, a roll-to-roll method, and the moving speed is determined by a T-die extruder (T of a resin material forming the thermoplastic resin layer 12 (T It adjusts suitably according to the discharge amount from a die-forming machine.

  According to the above extrusion coating method, the resin composition for forming the molten thermoplastic resin layer 12 is extruded and laminated on one surface of the substrate 11 from a T-die extruder (T-die film forming machine). As a result, the thermoplastic resin layer 12 can be firmly bonded to the substrate 11, and the solar cell protective sheet 1 can be manufactured with high productivity.

[Solar cell module]
FIG. 5 is a schematic cross-sectional view of a solar cell module according to an embodiment of the present invention. The solar cell module 10 according to the present embodiment includes a plurality of solar cells 2 made of crystalline silicon, amorphous silicon, or the like, which are photoelectric conversion elements, and a sealing material made of an electrical insulator that seals the solar cells 2 ( Packing layer) 3, a glass plate 4 laminated on the surface (upper surface in FIG. 5) of the sealing material 3, and a back surface protection sheet (laminated on the lower surface in FIG. 5) It is comprised from the protection sheet 1 for solar cells as a back sheet | seat.

  In addition, the protective sheet 1 for solar cells is laminated | stacked on the sealing material 3 so that the thermoplastic resin layer 12 may become the sealing material 3 side, and it adheres with respect to the sealing material 3 by this thermoplastic resin layer 12 Power is high. Moreover, since the solar cell protective sheet 1 in the present embodiment has a small amount of curl, warping of the obtained solar cell module 10 is suppressed. Therefore, it is possible to prevent problems caused when the solar cell module 10 is installed or damage of the solar cell module 10 due to warpage of the solar cell module 10.

  The material of the sealing material 3 is preferably an olefin resin, for example, preferably an olefin resin exemplified as a main component of the thermoplastic resin layer 12, having a high gas barrier property against oxygen or the like, and having a crosslinking. From the viewpoints of ease and availability, an ethylene-vinyl acetate copolymer (EVA) is particularly preferable. When the material of the sealing material 3 is an olefin resin, the affinity with the thermoplastic resin layer 12 mainly composed of the olefin resin is increased, and the adhesive force between the thermoplastic resin layer 12 and the sealing material 3 is increased. Get higher.

  The method for producing the solar cell module 10 is not particularly limited. For example, the solar cell 2 is sandwiched between two sheets constituting the encapsulant 3, and the solar cell protective sheet is provided on one exposed surface of the sheet. 1. The solar cell module 10 can be manufactured by installing the glass plate 4 on the other exposed surface and pressing and integrating them while heating. At this time, the protective sheet 1 for solar cells is joined to the sealing material 3 by thermal fusion of the thermoplastic resin layer 12 and the sealing material 3.

  In addition, as shown in FIG. 6, instead of the glass plate 4, the solar cell protective sheet 1 can be used as a surface protective sheet (front sheet). In this case, if a flexible substrate is used for the solar battery cell, a solar battery module having flexibility can be obtained. Thus, by making the solar cell module flexible, it becomes possible to mass-produce by roll-to-roll. In addition, since the flexible solar cell module can be fitted to an object having an arched or parabolic wall surface, it can be installed on a dome-shaped building or a soundproof wall of an expressway. .

  The embodiment described above is described for facilitating understanding of the present invention, and is not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

  EXAMPLES Hereinafter, although an Example etc. demonstrate this invention further more concretely, the scope of the present invention is not limited to these Examples etc.

[Example 1]
One side of a PET film (trade name: Melinex S, thickness 125 μm, manufactured by Teijin DuPont Films Ltd.) as a substrate is subjected to corona treatment (output 2000 W), and a T-die film forming machine (cylinder temperature: 230 to 300 ° C.). , T die temperature: 300 ° C.), a PET resin corona-treated surface having a density of 880 g / m ³ polyethylene resin (manufactured by Sumitomo Chemical Co., Ltd., trade name: Excelen CX4002) as a thickness of 100 μm. A thermoplastic resin layer was formed by extrusion coating to obtain a solar cell protective sheet having the configuration shown in FIG.

[Example 2]
In Example 1, the same operation as in Example 1 was performed except that a polyethylene resin having a density of 890 g / m ³ (product name: Evolue SP900100) was used as the olefin resin of the thermoplastic resin layer. It performed and the protective sheet for solar cells of the structure shown in FIG. 1 was obtained.

Example 3
In Example 1, as the olefin resin of the thermoplastic resin layer, a polyethylene resin having a density of 895 g / m ³ (manufactured by Sumitomo Chemical Co., Ltd., trade name: Excellen EUL731-M) was used. Operation was performed to obtain a solar cell protective sheet having the configuration shown in FIG.

Example 4
In Example 1, the same operation as in Example 1 except that a polyethylene resin having a density of 905 g / m ³ (trade name: Lumitac 43-1) was used as the olefin resin of the thermoplastic resin layer. The solar cell protective sheet having the configuration shown in FIG. 1 was obtained.

Example 5
In Example 1, as the olefin-based resin of the thermoplastic resin layer, polyethylene resin density of 905 g / ^{m 3} (manufactured by Tosoh Corporation, trade name: Rumitakku 43-1) and 50 parts by weight, a polyethylene of density of 895 g / ^{m 3} Except for using 50 parts by mass of resin (manufactured by Sumitomo Chemical Co., Ltd., trade name: Excellen EUL731-M) (blend resin density: 900 g / m ³ ), the same operation as in Example 1 was performed. A solar cell protective sheet having the structure shown in FIG. 1 was obtained.

Example 6
In Example 1, the same operation as in Example 1 except that a polyethylene resin having a density of 915 g / m ³ (trade name: Lumitac 54-1) was used as the olefin resin of the thermoplastic resin layer. The solar cell protective sheet having the configuration shown in FIG. 1 was obtained.

Example 7
In Example 1, as the olefin resin of the thermoplastic resin layer, the same operation as in Example 1 except that a polyethylene resin having a density of 900 g / m ³ (trade name: Lumitac 22-6, manufactured by Tosoh Corporation) was used. The solar cell protective sheet having the configuration shown in FIG. 1 was obtained.

Example 8
In Example 1, as the olefin-based resin of the thermoplastic resin layer, a polypropylene resin Density 890 g / ^{m 3} (Prime Polymer Co., Ltd., trade name: Prime Polypro F-744NP) and 50 parts by weight, polyethylene having a density of 905 g / ^{m 3} The same operation as in Example 1 was carried out except that 50 parts by mass of a resin based on Tosoh Corporation (trade name: Lumitac 43-1) was used (density of blend resin: 898 g / m ³ ). A solar cell protective sheet having the structure shown in FIG. 1 was obtained.

[Comparative Example 1]
In Example 1, as the olefin resin of the thermoplastic resin layer, the same operation as in Example 1 was performed except that a polyethylene resin having a density of 918 g / m ³ (trade name: Novatec LC605Y, manufactured by Nippon Polyethylene Co., Ltd.) was used. It performed and the protective sheet for solar cells of the structure shown in FIG. 1 was obtained.

[Comparative Example 2]
In Example 1, 70 parts by mass of a polypropylene resin having a density of 922 g / m ³ (trade name: Petrocene 204) manufactured by Tosoh Corporation and a polyethylene resin having a density of 895 g / m ³ (Tosoh Corporation) were used as the olefin resin of the thermoplastic resin layer. Except for using a blend of 30 parts by mass (trade name: Excellen EUL 731-M) manufactured by the company (density of blend resin: 914 g / m ³ ), the same operation as in Example 1 was performed, and FIG. A solar cell protective sheet having the structure shown was obtained.

[Comparative Example 3]
In Example 1, as the olefin resin of the thermoplastic resin layer, a polyethylene resin having a density of 870 g / m ³ (trade name: TAFMER P-0180, manufactured by Mitsui Chemicals) was used. Operation was performed to obtain a solar cell protective sheet having the configuration shown in FIG.

[Comparative Example 4]
In Example 1, 65 parts by mass of a polyethylene resin having a density of 918 g / m ³ (manufactured by Nippon Polyethylene Co., Ltd., trade name: Novatec LC605Y) and an ethylene-acrylic having a density of 930 g / m ³ are used as the olefin resin of the thermoplastic resin layer. The same operation as in Example 1 was performed except that 35 parts by mass of butyl acid copolymer resin (trade name: LOTRYL 30BA02, manufactured by Arkema Co., Ltd.) was used (density of blend resin: 922 g / m ³ ). The solar cell protective sheet having the structure shown in FIG. 1 was obtained.

[Test Example 1] <Measurement of heat of fusion>
About the olefin resin which comprises the thermoplastic resin layer in an Example and a comparative example, the measurement of a calorie | heat amount is measured on condition of the following using a differential scanning calorimeter (the TI instrument company make, model number: Q2000). And data was collected.
-Sample adjustment conditions Heating was performed from -40 ° C to 250 ° C at a heating rate of 20 ° C / min.
Measurement conditions After holding at 250 ° C. for 5 minutes, the sample was cooled to −40 ° C. at a temperature drop rate of 20 ° C./min, and the change in the amount of heat was measured.
The area of the peak accompanying solidification was calculated from the obtained data, and this was defined as the heat of fusion ΔH (J / g). The results are shown in Table 1.

[Test Example 2] <Density measurement>
About the olefin resin which comprises the thermoplastic resin layer in an Example and a comparative example, the density (g / m < ³ >) was measured according to JISK7112. When measuring a blend of two or more kinds of resins, after kneading at 210 ° C. with a biaxial kneader (manufactured by Toyo Seiki Seisakusho Co., Ltd., product name: Labo Plast Mill) and quenching in a water bath Measurements were again made on the pellets processed again. The results are shown in Table 1.

[Test Example 3] <MFR measurement>
About the olefin resin which comprises the thermoplastic resin layer in an Example and a comparative example, based on JISK7210: 1999, using a flow tester (made by Shimadzu Corporation, product name: CFT-100D), a load of 2.16 kg, MFR (g / 10 min) was measured at a test temperature of 190 ° C. The results are shown in Table 1.

[Test Example 4] <Measurement of curl amount>
The protective sheet for a solar cell produced in the example or the comparative example was cut into a 300 mm × 300 mm square, placed on a horizontal table, and the vertical distance (mm) from the table surfaces at the four corners was measured. The average value of each distance of the obtained four places was calculated, and this was taken as the curl amount (mm). The results are shown in Table 1.

[Test Example 5] <Blocking evaluation>
The protective sheet for a solar cell produced in the example or the comparative example was wound 100 m on a paper tube having a diameter of 3 inches and a width of 350 mm to produce an evaluation sample. The evaluation sample was stored in an atmosphere of 40 ° C. for one week, and then the situation when it was unwound again was evaluated according to the following criteria. The results are shown in Table 1.
○: Can be unwound without resistance.
Δ: Can be unwound but partially blocked, leaving a blocking mark on the sheet surface.
X: Blocking occurs partially or entirely, and unwinding is not possible.

  As can be seen from Table 1, the solar cell protective sheet of the example satisfying the conditions of the present invention had a small curl amount and no blocking problem.

  The solar cell protective sheet according to the present invention is suitably used as a back sheet of a solar cell module, for example.

DESCRIPTION OF SYMBOLS 1 ... Protective sheet for solar cells 11 ... Base material 12 ... Thermoplastic resin layer 13 ... Fluorine resin layer 14 ... Deposition layer 15 ... Adhesion layer 16 ... Metal sheet 2 ... Solar cell 3 ... Sealing material 4 ... Glass plate 10 ... Solar cell module

  The present invention relates to a solar cell protective sheet used as a surface protective sheet or a back surface protective sheet of a solar cell module, a method for producing the same, and a solar cell module using the solar cell protective sheet.

  Solar cell modules that convert solar light energy into electrical energy are attracting attention as a clean energy source that can generate electricity without emitting carbon dioxide in response to environmental problems such as air pollution and global warming.

  Generally, a solar cell module is composed of a solar cell made of crystalline silicon, amorphous silicon, or the like that performs photoelectric conversion, a sealing material (filling layer) made of an electrical insulator that seals the solar cell, and the surface of the sealing material. It is comprised from the surface protection sheet (front sheet) laminated | stacked on (light-receiving surface) and the back surface protection sheet (back sheet) laminated | stacked on the back surface of the sealing material. In order to provide the solar module with the weather resistance and durability that can withstand long-term use outdoors and indoors, the solar cells and sealing material are protected from wind, rain, moisture, dust, mechanical shock, etc. It is necessary to keep the inside of the battery module sealed from the outside air. For this reason, the protection sheet for solar cells is required to have moisture resistance and weather resistance that can withstand long-term use.

  Patent Document 1 discloses a solar cell module in which a silicon power generation element is sealed with a sealing material made of an ethylene-vinyl acetate copolymer sheet, and a back sheet is laminated on the back surface of the sealing material. As a back sheet, a sheet in which a fluorine-based plastic film having weather resistance (Tedlar film manufactured by DuPont) is bonded to one side or both sides of a layer that prevents water vapor permeation, such as metal, is disclosed. This back sheet is heat-bonded to the sealing material.

  However, the conventional back sheet as disclosed in Patent Document 1 has a problem in that the back sheet peels off from the sealing material and water vapor enters the sealing material because of low adhesion to the sealing material. Thus, it has been proposed to improve the adhesion (adhesion) to the above-mentioned sealing material by providing a heat-fusible layer on the back sheet.

  Specifically, Patent Document 2 discloses a back sheet laminated on the back surface of a filler in a solar cell module using an ethylene-vinyl acetate copolymer as a filler, and includes an epoxy compound and / or a silane compound. A heat-fusible layer made of a heat-fusible resin composed mainly of a graft-modified ethylene- (meth) acrylic acid ester copolymer, ethylene-vinyl acetate copolymer, or a mixture thereof is laminated on a heat-resistant film. Has been disclosed.

Japanese Patent Laid-Open No. 6-177412 JP 2008-108947 A

  In patent document 2, when manufacturing a back sheet, a heat-fusible layer is laminated | stacked with an extrusion coating method with respect to a heat resistant film. Such a method of forming a heat-fusible layer has high productivity, but has a problem that shrinkage occurs due to cooling of the heat-fusible layer and curls occur in the width direction or the flow direction of the roll. If the solar cell module is warped along with the curl of the back sheet, not only will the malfunction occur when the solar cell module is installed, but the solar cell module may be damaged.

  This invention is made | formed in view of such an actual condition, While being excellent in the adhesiveness with respect to the sealing material of a solar cell module, the protective sheet for solar cells which can suppress the curvature which arises in a solar cell module, and its It is an object of the present invention to provide a solar cell module that is excellent in the manufacturing method and the adhesiveness between the sealing material and the protective sheet and in which the warpage is suppressed.

In order to achieve the above object, first, the present invention provides a solar cell protective sheet comprising a base material and a thermoplastic resin layer laminated on at least one surface of the base material, The solar resin characterized in that the plastic resin layer has a density of 875 to 920 kg / m ³ and has as its main component an olefin resin having a heat of fusion ΔH obtained by a differential scanning calorimeter of 100.0 J / g or less. A protective sheet for a battery is provided (Invention 1).

  In the solar cell protective sheet according to the above invention (Invention 1), the thermoplastic resin layer is mainly composed of an olefin resin, so that the solar cell module has excellent adhesion to the sealing material. In addition, due to the low density and low crystallinity of the olefin resin that satisfies the above requirements, the shrinkage rate of the thermoplastic resin layer is small, so that the curl amount of the protective sheet for solar cells is small. The solar cell module can be prevented from warping due to the curling of the protective sheet.

  In the said invention (invention 1), it is preferable that the said olefin resin contains 60-100 mass% of ethylene as a monomer unit (invention 2).

  In the said invention (invention 1 and 2), it is preferable that the said thermoplastic resin layer is formed by extrusion coating (invention 3).

  In the said invention (invention 1-3), it is preferable that the said thermoplastic resin layer is a single layer (invention 4).

  In the said invention (invention 1-4), it is preferable that the said thermoplastic resin layer is a layer adhere | attached with the sealing material which comprises a solar cell module (invention 5).

2ndly this invention is a manufacturing method of the protection sheet for solar cells provided with the base material and the thermoplastic resin layer laminated | stacked on the at least one surface of the said base material, Comprising: A density is 875-920 kg / m. ^{3. A} thermoplastic resin composition mainly composed of an olefin resin having a heat of fusion ΔH of 100.0 J / g or less obtained by a differential scanning calorimeter is extrusion coated on at least one surface of the substrate. Then, the manufacturing method of the protection sheet for solar cells characterized by forming the said thermoplastic resin layer is provided (invention 6).

  3rdly this invention is a solar cell module provided with the photovoltaic cell, the sealing material which seals the said photovoltaic cell, and the protective sheet laminated | stacked on the said sealing material, Comprising: The said protective sheet is And a solar cell module comprising the protective sheet for solar cells (invention 5), wherein the protective sheet is bonded to the sealing material via the thermoplastic resin layer (invention 7). ).

  The solar cell protective sheet according to the present invention is excellent in adhesion to the sealing material of the solar cell module, and can suppress warping that occurs in the solar cell module because the curl amount is small. Moreover, according to the manufacturing method of the protection sheet for solar cells which concerns on this invention, the protection sheet for solar cells which has the above outstanding effects is obtained. Furthermore, in the solar cell module according to the present invention, the adhesiveness between the sealing material and the protective sheet is excellent, and warpage due to curling of the protective sheet is suppressed.

It is a schematic sectional drawing of the protection sheet for solar cells which concerns on one Embodiment of this invention. It is a schematic sectional drawing of the protection sheet for solar cells which concerns on other embodiment of this invention. It is a schematic sectional drawing of the protection sheet for solar cells which concerns on other embodiment of this invention. It is a schematic sectional drawing of the protection sheet for solar cells which concerns on other embodiment of this invention. It is a schematic sectional drawing of the solar cell module which concerns on one Embodiment of this invention. It is a schematic sectional drawing of the solar cell module which concerns on other embodiment of this invention.

Hereinafter, embodiments of the present invention will be described.
[Protective sheet for solar cell]
As shown in FIG. 1, the solar cell protective sheet 1 according to this embodiment includes a base material 11 and a thermoplastic resin layer 12 laminated on one surface of the base material 11 (upper surface in FIG. 1). I have. This solar cell protective sheet 1 is used as a surface protective sheet (front sheet) or a back surface protective sheet (back sheet) of a solar cell module.

  As the base material 11, any material that has electrical insulation and can be laminated with the thermoplastic resin layer 12 may be used. Usually, a material mainly composed of a resin film is used.

  As a resin film used for the base material 11, what is generally used as the resin film in the solar cell module backsheet is selected. Examples of such resin films include polyolefin resins such as polyethylene and polypropylene, polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate, polyamide resins such as nylon (trade name), polycarbonate resins, and polystyrene. A film or sheet made of a resin such as a resin, a polyacrylonitrile resin, a polyvinyl chloride resin, a polyvinyl acetal resin, a polyvinyl butyral resin, or a fluorine resin is used. Among these resin films, a film made of a polyester resin is preferable, and a PET film is particularly preferable.

  In addition, the said resin film may contain various additives, such as a pigment, a ultraviolet absorber, a ultraviolet stabilizer, a flame retardant, a plasticizer, an antistatic agent, a lubricant, and an antiblocking agent, as needed. Examples of the pigment include titanium dioxide and carbon black. Examples of the ultraviolet absorber include benzophenone series, benzotriazole series, oxalic acid anilide series, cyanoacrylate series, and triazine series.

  Here, when using the solar cell protective sheet 1 according to this embodiment as a back sheet of a solar cell module, the resin film preferably contains a pigment that reflects visible light. Moreover, when using the solar cell protective sheet 1 according to the present embodiment as a front sheet of a solar cell module, it is preferable not to contain a pigment that reduces the light transmittance in the visible light region, thereby improving the weather resistance. It is more preferable to contain an ultraviolet absorber for the purpose.

  The surface of the resin film on which the thermoplastic resin layer 12 is laminated is preferably subjected to surface treatment such as corona treatment, plasma treatment, and primer treatment in order to improve adhesion to the thermoplastic resin layer 12. .

  The thickness of the base material 11 is appropriately set based on the electrical insulation required for the solar cell module. For example, when the substrate 11 is a resin film, the thickness is preferably 10 to 300 μm. More specifically, when the base material 11 is a PET film, the thickness is preferably 10 to 300 μm, more preferably 20 to 250 μm, from the viewpoint of electrical insulation and weight reduction. It is especially preferable that it is -200 micrometers.

Although the thermoplastic resin layer 12 in this embodiment is for adhere | attaching the solar cell protective sheet 1 on the sealing material of a solar cell module, this invention is not limited to this. The thermoplastic resin layer 12 in the present embodiment has a density of 875 to 920 kg / m ³ , preferably 880 to 915 kg / m ³ , and a heat of fusion ΔH obtained by a differential scanning calorimeter is 100.0 J / g or less. The main component is an olefin resin, preferably 95 J / g or less. The density is a value obtained by measurement according to JIS K7112. Here, the lower limit of the heat of fusion ΔH is naturally determined by the relationship with the density and the skeleton of each resin, but is theoretically preferably 0.

  The thermoplastic resin layer 12 mainly composed of an olefin resin has high adhesiveness to the sealing material of the solar cell module due to the excellent heat-sealing action of the olefin resin. Further, as described above, an olefin resin having a low density or an ultra-low density and a low heat of fusion, that is, low crystallinity, has a small shrinkage rate even when cooled from a heated and melted state. Therefore, by using the olefin-based resin as a main component of the thermoplastic resin layer 12, even when the thermoplastic resin layer 12 is formed on the base material 11 by extrusion coating, stress acting toward the base material 11 is hardly generated. Therefore, the curl amount of the protective sheet 1 for solar cells is small. Thereby, it can suppress that curvature arises in a solar cell module resulting from the curl of the protection sheet 1 for solar cells. Specifically, when the solar cell protective sheet 1 is cut into a 300 mm × 300 mm square and placed on a horizontal table, the warpage of the solar cell module is suppressed when the vertical curl amount is 20 mm or less. However, according to the solar cell protective sheet 1 including the thermoplastic resin layer 12 mainly composed of the olefin-based resin, the curl amount can be suppressed to 20 mm or less.

When the density of the olefin-based resin is less than 875 kg / m ³ , the thermoplastic resin layer 12 is tacked, and the wound solar cell protective sheet 1 is blocked, and the solar cell protective sheet 1 is blocked. A mark may be attached, or the wound solar cell protective sheet 1 may not be unwound. On the other hand, when the density of the olefin resin exceeds 920 kg / m ³ , the curl amount of the solar cell protective sheet 1 increases. Further, even when the heat of fusion ΔH of the olefin resin exceeds 100.0 J / g, the curl amount of the solar cell protective sheet 1 increases. When the amount of curl of the solar cell protective sheet 1 is increased, a large warp is generated in the obtained solar cell module, and a problem occurs when the solar cell module is installed, or the solar cell module is damaged.

  The melt flow rate (MFR) of the olefin resin is preferably 1 to 20 g / 10 min, and particularly preferably 2 to 10 g / 10 min. When the MFR of the olefin resin is within the above range, the thermoplastic resin layer 12 can be formed by extrusion coating.

Examples of the olefin resin include low-density polyethylene (LDPE, density: 910 kg / m ³ or more, less than 915 kg / m ³ ), very low-density polyethylene (VLDPE, density: 880 kg / m ³ or more, 910 kg / m ³⁾ polyethylene resins such as polypropylene resin (PP), polyethylene - polypropylene polymer, an olefin-based elastomer (TPO), cycloolefin resins, ethylene - vinyl acetate copolymer (EVA), ethylene - vinyl acetate - maleic anhydride Examples include acid copolymers, ethylene- (meth) acrylic acid copolymers, ethylene-butyl acrylate copolymers (EBA), ethylene- (meth) acrylic acid esters-maleic anhydride copolymers, and the like. Can be used alone or in admixture of two or more. In the present specification, (meth) acrylic acid means both acrylic acid and methacrylic acid. The same applies to other similar terms.

  Among the olefin-based resins, a polyethylene-based resin containing 60 to 100% by mass, particularly 70 to 99.5% by mass of ethylene as a monomer unit is preferable, and further, ethylene as a monomer unit is preferably 60 to 100% by mass. %, In particular 70 to 99.5% by mass of ultra-low density polyethylene is preferred. Such a polyethylene resin has excellent processability and has a high affinity for a sealing material for a solar cell module, particularly a sealing material made of an ethylene-vinyl acetate copolymer, which is the same ethylene type, and has a very high adhesiveness. Excellent.

  Even if the thermoplastic resin layer 12 in the present embodiment is a single layer, curling of the solar cell protective sheet 1 can be suppressed, so that it is preferable that the thermoplastic resin layer 12 is also a single layer in terms of material cost and manufacturing cost.

  The thermoplastic resin layer 12 should just contain the olefin resin mentioned above as a main component, Specifically, it is preferable to contain 60 mass% or more of the said olefin resin, and to contain 80 mass% or more. Is more preferable, and it is particularly preferable to contain 90% by mass or more. Naturally, the thermoplastic resin layer 12 may be made of only an olefin resin.

  In addition to the olefin-based resin, the thermoplastic resin layer 12 may include various additives such as pigments, ultraviolet absorbers, ultraviolet stabilizers, flame retardants, plasticizers, antistatic agents, lubricants, and antiblocking agents as necessary. May be included.

  The thickness of the thermoplastic resin layer 12 is not particularly limited as long as it exhibits desired adhesion to the adherend and does not impair the effects of the present invention. Specifically, the thickness of the thermoplastic resin layer 12 is preferably 1 to 200 μm, more preferably 10 to 180 μm, and 50 to 150 μm from the viewpoint of electrical insulation and weight reduction. Is more preferable, and it is especially preferable that it is 80-120 micrometers.

  Here, as shown in FIG. 2, it is preferable that a fluororesin layer 13 is provided on the surface of the base material 11 on which the thermoplastic resin layer 12 is not laminated (the lower surface in FIG. 2). By providing the fluororesin layer 13 in this manner, the weather resistance and chemical resistance of the solar cell protective sheet 1 are improved. In addition, when the base material 11 consists of a resin film, in order to improve the adhesiveness with the fluororesin layer 13, the surface by which the fluororesin layer 13 of the said resin film is laminated | stacked is a corona treatment, a plasma treatment, a primer. Surface treatment such as treatment is preferably performed.

  The fluororesin layer 13 is not particularly limited as long as it contains fluorine. For example, the fluororesin layer 13 is constituted by a sheet having a fluorine-containing resin (fluorine-containing resin sheet), a coating film formed by applying a paint containing the fluorine-containing resin, or the like. Is done. Among these, from the viewpoint of making the fluororesin layer 13 thinner in order to reduce the weight of the solar cell protective sheet 1, a coating film formed by applying a paint having a fluorine-containing resin is preferable.

  As the fluorine-containing resin sheet, for example, a sheet obtained by processing a resin mainly composed of polyvinyl fluoride (PVF), ethylene chlorotrifluoroethylene (ECTFE), or ethylene tetrafluoroethylene (ETFE) is used. Examples of the resin mainly composed of PVF include E.I. I. “Tedlar” (trade name) manufactured by du Pont de Nemours and Company. Examples of the resin mainly composed of ECTFE include “Halar” (trade name) manufactured by Solvay Solexis. Examples of the resin mainly composed of ETFE include “Fluon” (trade name) manufactured by Asahi Glass Co., Ltd.

  When the fluororesin layer 13 is a fluorine-containing resin sheet, the fluororesin layer 13 is laminated on the base material 11 via an adhesive layer. The adhesive layer is composed of an adhesive having adhesiveness to the substrate 11 and the fluorine-containing resin sheet. Examples of such adhesives include acrylic adhesives, polyurethane adhesives, epoxy adhesives, polyester adhesives, and polyester polyurethane adhesives. These adhesives may be used individually by 1 type, and may be used in combination of 2 or more type.

  On the other hand, when the fluororesin layer 13 is a coating film formed by applying a paint having a fluorine-containing resin, the paint containing the fluorine-containing resin is usually applied directly to the substrate 11 without using an adhesive layer. The fluororesin layer 13 is laminated on the base material 11.

  The paint containing the fluorine-containing resin is not particularly limited as long as it is dissolved in a solvent or dispersed in water and can be applied.

  The fluorine-containing resin contained in the paint is not particularly limited as long as it does not impair the effects of the present invention and contains fluorine. However, it is usually soluble in a paint solvent (organic solvent or water) and can be crosslinked. Things are used. As the fluorine-containing resin, it is preferable to use a fluoroolefin resin having a curable functional group. Examples of such a fluoroolefin resin include tetrafluoroethylene (TFE), isobutylene, vinylidene fluoride (VdF), a copolymer comprising hydroxybutyl vinyl ether and other monomers, or TFE, VdF, hydroxybutyl vinyl ether and other Examples thereof include a copolymer composed of monomers.

  Specific examples of fluoroolefin resins include “LUMIFLON” (trade name) manufactured by Asahi Glass Co., “CEFRAL COAT” (trade name) manufactured by Central Glass Co., Ltd., and “FLUONATE” (trade name) manufactured by DIC Corporation. Polymers mainly composed of fluoroethylene (CTFE), polymers mainly composed of tetrafluoroethylene (TFE) such as “ZEFFLE” (trade name) manufactured by Daikin Industries, Ltd .; I. Polymers having a fluoroalkyl group, such as “Zonyl” (trade name) manufactured by du Pont de Nemours and Company, “Unidyne” (trade name) manufactured by Daikin Industries, Ltd. Can be mentioned. Among these, from the viewpoint of weather resistance, pigment dispersibility, and the like, a polymer containing CTFE as a main component and a polymer containing TFE as a main component are preferable, and “LUMIFLON” and “ZEFFLE” are particularly preferable.

  “LUMIFLON” is an amorphous resin containing CTFE and several types of specific alkyl vinyl ethers (VE) or hydroxyalkyl vinyl ethers as main structural units. A resin having a monomer unit of hydroxyalkyl vinyl ether such as “LUMIFLON” is preferable because it is excellent in solvent solubility, cross-linking reactivity, substrate adhesion, pigment dispersibility, hardness and flexibility.

  “ZEFFLE” is a copolymer of TFE and organic solvent-soluble hydrocarbon olefins. Among them, those containing hydrocarbon olefins with highly reactive hydroxyl groups are solvent-soluble, crosslinking reactivity, and substrate adhesion. And pigment dispersibility is preferable.

  Examples of the copolymerizable monomer that forms the fluorine-containing resin contained in the paint include vinyl acetate, vinyl propionate, butyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl caproate, vinyl versatate, vinyl laurate, Vinyl esters of carboxylic acids such as vinyl stearate, vinyl cyclohexyl carboxylate and vinyl benzoate, alkyl vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, butyl vinyl ether and cyclohexyl vinyl ether, CTFE, vinyl fluoride (VF), VdF and fluorine And fluorine-containing monomers such as fluorinated vinyl ethers.

  Further, the fluorine-containing resin contained in the paint may be a resin composed of one or more monomers or a terpolymer. Examples of the terpolymer include “Dyneon THV” (trade name) manufactured by 3M Company, which is a terpolymer of VdF, TFE, and hexafluoropropylene. Such a terpolymer is preferable because it can impart the properties of each monomer to the resin. In particular, “Dyneon THV” is preferable because it can be produced at a relatively low temperature, can be bonded to an elastomer or a hydrocarbon-based plastic, and is excellent in flexibility and optical transparency.

  The coating material may contain a crosslinking agent, a curing catalyst, a solvent and the like in addition to the fluorine-containing resin described above, and may further contain an inorganic compound such as a pigment and a filler, if necessary.

  The solvent contained in the paint is not particularly limited as long as it does not impair the effects of the present invention. For example, methyl ethyl ketone (MEK), cyclohexanone, acetone, methyl isobutyl ketone (MIBK), toluene, xylene, methanol, isopropanol, ethanol , Heptane, ethyl acetate, isopropyl acetate, n-butyl acetate or n-butyl alcohol, and a solvent containing any one or more organic solvents is preferably used.

  The pigment or filler contained in the paint is not particularly limited as long as it does not impair the effects of the present invention. For example, titanium dioxide, carbon black, perylene pigment, mica, polyamide powder, boron nitride, zinc oxide, aluminum oxide Silica, ultraviolet absorbers, preservatives, desiccants and the like are used. Specifically, as pigments and fillers, E.I. is rutile titanium dioxide treated with silicon oxide in order to impart durability. I. “Ti-Pure R105” (trade name) manufactured by du Pont de Nemours and Company, and “CAB-O-SIL TS” manufactured by Cabot, which is a hydrophobic silica in which hydroxyl groups on the silica surface are modified by surface treatment of dimethyl silicone. “720” (trade name) is preferably used.

  The coating film of the fluorine-containing resin is preferably cured with a crosslinking agent in order to improve weather resistance and scratch resistance. The crosslinking agent is not particularly limited as long as the effects of the present invention are not impaired, and metal chelates, silanes, isocyanates, or melamines are preferably used. Assuming that the solar cell protective sheet 1 is used outdoors for a long period of time, aliphatic isocyanates are preferable as the crosslinking agent from the viewpoint of weather resistance.

  The curing catalyst contained in the coating is not particularly limited as long as it does not impair the effects of the present invention, and examples thereof include tin dibutyldilaurate for promoting the crosslinking between the fluorine-containing resin and isocyanate.

  The composition of the coating is not particularly limited as long as the effects of the present invention are not impaired. For example, the coating composition is prepared by mixing a fluorine-containing resin, a pigment, a crosslinking agent, a solvent, and a catalyst. As composition ratio, when the whole coating material is 100 mass%, it is preferable that the content rate of fluorine-containing resin is 3-80 mass%, especially 25-50 mass%, and the content rate of a pigment is 5-60 mass%. %, Particularly 10 to 30% by mass, and the solvent content is preferably 20 to 80% by mass, and particularly preferably 25 to 65% by mass.

As a method of applying the paint to the substrate 11, a known method is used, for example,
What is necessary is just to apply | coat the fluororesin layer 13 obtained by bar coating method, knife coating method, roll coating method, blade coating method, die coating method, gravure coating method, etc. so that it may become desired thickness.

  The drying temperature of the coating material applied to the substrate 11 may be any temperature that does not impair the effects of the present invention, and is preferably in the range of 50 to 130 ° C. from the viewpoint of reducing the influence on the substrate 11.

  The thickness of the fluororesin layer 13 is set in consideration of weather resistance, chemical resistance, weight reduction, and the like, and is preferably 5 to 50 μm, and particularly preferably 10 to 30 μm.

  Further, a vapor deposition layer 14 may be provided between the base material 11 and the fluororesin layer 13 on the surface of the base material 11 on which the thermoplastic resin layer 12 is not laminated, as shown in FIG. 4, the metal sheet 16 may be laminated via the adhesive layer 15, and the surface of the vapor deposition layer 14 or the metal sheet 16 (the lower surface in FIGS. 3 and 4) is the same as described above. A fluororesin layer 13 may be provided. Thus, by providing the vapor deposition layer 14 or the metal sheet 16, the moisture-proof property and weather resistance of the protection sheet 1 for solar cells can be improved.

  In addition, when the base material 11 consists of a resin film, in order to improve the adhesiveness with the vapor deposition layer 14 or the contact bonding layer 15, the surface by which the vapor deposition layer 14 or the contact bonding layer 15 of the said resin film is laminated | stacked is a corona. Surface treatment such as treatment, plasma treatment, and primer treatment is preferably performed.

  The vapor deposition layer 14 is comprised from inorganic materials, such as a metal or a semimetal, or an oxide, nitride, silicide, etc. of a metal or a semimetal, By being comprised from such material, the base material 11 (protective sheet for solar cells) It is possible to impart moisture resistance (water vapor barrier property) and weather resistance to 1).

  Examples of the vapor deposition method for forming the vapor deposition layer 14 include chemical vapor deposition such as plasma chemical vapor deposition, thermal chemical vapor deposition, and photochemical vapor deposition, or vacuum vapor deposition, sputtering, and ion plating. A physical vapor phase method such as a method is used. Among these methods, the sputtering method is preferable in consideration of operability and controllability of the layer thickness.

  Examples of the metal used as the raw material of the vapor deposition layer 14 include aluminum (Al), magnesium (Mg), calcium (Ca), potassium (K), tin (Sn), sodium rim (Na), titanium (Ti), and lead. (Pb), zirconium (Zr), yttrium (Y) and the like. Examples of the semimetal include silicon (Si) and boron (B). Examples of these metal or metalloid oxides, nitrides, and oxynitrides include aluminum oxide, tin oxide, silicon oxide, silicon nitride, silicon oxynitride, and aluminum oxynitride.

  The vapor deposition layer 14 may be made of one kind of inorganic material or may be made of a plurality of kinds of inorganic materials. When the vapor deposition layer 14 is made of a plurality of types of inorganic materials, it may be a vapor deposition layer having a laminated structure in which the layers made of the respective inorganic materials are sequentially vapor deposited, or may be a vapor deposition layer in which a plurality of types of inorganic materials are vapor deposited simultaneously. May be.

  The thickness of the vapor deposition layer 14 is appropriately set in consideration of the water vapor barrier property, and is changed depending on the type of inorganic material used, vapor deposition density, and the like. Usually, it is preferable that the thickness of the vapor deposition layer 14 is 5-200 nm, and it is especially preferable that it is 10-100 nm.

  On the other hand, the metal sheet 16 can also provide moisture resistance (water vapor barrier property) and weather resistance to the base material 11 (protective sheet 1 for solar cells), similarly to the vapor deposition layer 14. The material of the metal sheet 16 is not particularly limited as long as it has such a function, and examples thereof include metals such as aluminum and aluminum alloys such as aluminum-iron alloys.

  The thickness of the metal sheet 16 is not particularly limited as long as the effects of the present invention are not impaired, but from the viewpoint of low pinhole occurrence frequency, high mechanical strength, high water vapor barrier properties, and weight reduction, etc. It is preferable that it is 5-100 micrometers, and it is especially preferable that it is 10-50 micrometers.

  The adhesive layer 15 is composed of an adhesive having adhesiveness to the base material 11 and the metal sheet 16. As the adhesive constituting the adhesive layer 15, for example, an acrylic adhesive, a polyurethane adhesive, an epoxy adhesive, a polyester adhesive, a polyester polyurethane adhesive, or the like is used. These adhesives may be used individually by 1 type, and may be used in combination of 2 or more type.

  Although the thickness of the contact bonding layer 15 is not specifically limited unless the effect of this invention is impaired, Usually, it is preferable that it is 1-20 micrometers, and it is especially preferable that it is 3-10 micrometers.

  In addition, in the above embodiment, although the solar cell protective sheet 1 in which the thermoplastic resin layer 12 was laminated on one surface of the base material 11 was illustrated, the solar cell protective sheet of the present invention is not limited thereto. The thermoplastic resin layer may also be laminated on the other surface of the substrate 11 (the surface opposite to the one surface).

[Method for producing protective sheet for solar cell]
In order to manufacture the solar cell protective sheet 1 according to the present embodiment (as an example, the solar cell protective sheet 1 shown in FIG. 1), the thermoplastic resin composition constituting the thermoplastic resin layer 12 is used as the base material 11. It is preferable to form the thermoplastic resin layer 12 on the substrate 11 by extrusion coating on at least one surface of the substrate 11. According to such an extrusion coating method, the protection sheet 1 for solar cells can be manufactured with high productivity and at low cost. Moreover, since it is not necessary to separately provide an adhesive layer for adhering the solar cell protective sheet 1 to the sealing material of the solar cell module, it is possible to prevent deterioration over time due to decomposition of the adhesive or the like.

  Specifically, using a T-die extruder or a T-die film forming machine, the resin composition for forming the thermoplastic resin layer 12 is melted and kneaded, and the substrate 11 is moved at a constant speed. Then, the molten resin composition is extruded and laminated on one surface of the base material 11 to form the thermoplastic resin layer 12 on the base material 11, thereby obtaining the solar cell protective sheet 1.

  In addition, as shown in FIGS. 2-4, when the other layer is formed in the base material 11, it is a thermoplastic resin layer in the surface of the side in which the said other layer of the base material 11 is not formed. 12 may be formed.

  The temperature at which the resin composition forming the thermoplastic resin layer 12 is melted is such that the base material 11 is not deformed by the temperature (heat) of the molten resin composition, and is preferably 80 to 350 ° C., and preferably 150 to 300 It is particularly preferable that the temperature is C.

  Moreover, the discharge amount from the T-die extruder (T-die film forming machine) of the resin composition forming the thermoplastic resin layer 12 depends on the thickness of the target thermoplastic resin layer 12 and the moving speed of the substrate 11. Are adjusted accordingly.

  The base material 11 is moved (conveyed) in the longitudinal direction at a constant speed by, for example, a roll-to-roll method, and the moving speed is determined by a T-die extruder (T of a resin material forming the thermoplastic resin layer 12 (T It adjusts suitably according to the discharge amount from a die-forming machine.

  According to the above extrusion coating method, the resin composition for forming the molten thermoplastic resin layer 12 is extruded and laminated on one surface of the substrate 11 from a T-die extruder (T-die film forming machine). As a result, the thermoplastic resin layer 12 can be firmly bonded to the substrate 11, and the solar cell protective sheet 1 can be manufactured with high productivity.

[Solar cell module]
FIG. 5 is a schematic cross-sectional view of a solar cell module according to an embodiment of the present invention. The solar cell module 10 according to the present embodiment includes a plurality of solar cells 2 made of crystalline silicon, amorphous silicon, or the like, which are photoelectric conversion elements, and a sealing material made of an electrical insulator that seals the solar cells 2 ( Packing layer) 3, a glass plate 4 laminated on the surface (upper surface in FIG. 5) of the sealing material 3, and a back surface protection sheet (laminated on the lower surface in FIG. 5) It is comprised from the protection sheet 1 for solar cells as a back sheet | seat.

  In addition, the protective sheet 1 for solar cells is laminated | stacked on the sealing material 3 so that the thermoplastic resin layer 12 may become the sealing material 3 side, and it adheres with respect to the sealing material 3 by this thermoplastic resin layer 12 Power is high. Moreover, since the solar cell protective sheet 1 in the present embodiment has a small amount of curl, warping of the obtained solar cell module 10 is suppressed. Therefore, it is possible to prevent problems caused when the solar cell module 10 is installed or damage of the solar cell module 10 due to warpage of the solar cell module 10.

  The material of the sealing material 3 is preferably an olefin resin, for example, preferably an olefin resin exemplified as a main component of the thermoplastic resin layer 12, having a high gas barrier property against oxygen or the like, and having a crosslinking. From the viewpoints of ease and availability, an ethylene-vinyl acetate copolymer (EVA) is particularly preferable. When the material of the sealing material 3 is an olefin resin, the affinity with the thermoplastic resin layer 12 mainly composed of the olefin resin is increased, and the adhesive force between the thermoplastic resin layer 12 and the sealing material 3 is increased. Get higher.

  The method for producing the solar cell module 10 is not particularly limited. For example, the solar cell 2 is sandwiched between two sheets constituting the encapsulant 3, and the solar cell protective sheet is provided on one exposed surface of the sheet. 1. The solar cell module 10 can be manufactured by installing the glass plate 4 on the other exposed surface and pressing and integrating them while heating. At this time, the protective sheet 1 for solar cells is joined to the sealing material 3 by thermal fusion of the thermoplastic resin layer 12 and the sealing material 3.

  In addition, as shown in FIG. 6, instead of the glass plate 4, the solar cell protective sheet 1 can be used as a surface protective sheet (front sheet). In this case, if a flexible substrate is used for the solar battery cell, a solar battery module having flexibility can be obtained. Thus, by making the solar cell module flexible, it becomes possible to mass-produce by roll-to-roll. In addition, since the flexible solar cell module can be fitted to an object having an arched or parabolic wall surface, it can be installed on a dome-shaped building or a soundproof wall of an expressway. .

  The embodiment described above is described for facilitating understanding of the present invention, and is not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

  EXAMPLES Hereinafter, although an Example etc. demonstrate this invention further more concretely, the scope of the present invention is not limited to these Examples etc.

[Example 1]
One side of a PET film (trade name: Melinex S, thickness 125 μm, manufactured by Teijin DuPont Films Ltd.) as a substrate is subjected to corona treatment (output 2000 W), and a T-die film forming machine (cylinder temperature: 230 to 300 ° C.). , T die temperature: 300 ° C.), PET film corona treatment with a density of 880 kg / m ³ of polyethylene resin (manufactured by Sumitomo Chemical Co., Ltd., trade name: Excelen CX4002) as an olefin resin to a thickness of 100 μm. A thermoplastic resin layer was formed by extrusion coating on the surface to obtain a solar cell protective sheet having the structure shown in FIG.

[Example 2]
In Example 1, the same operation as in Example 1 was used except that a polyethylene resin having a density of 890 kg / m ³ (trade name: Evolue SP900100) was used as the olefin resin of the thermoplastic resin layer. The solar cell protective sheet having the configuration shown in FIG. 1 was obtained.

Example 3
In Example 1, a polyethylene resin having a density of 895 kg / m ³ (manufactured by Sumitomo Chemical Co., Ltd., trade name: Excellen EUL731-M) was used as the olefin resin of the thermoplastic resin layer. The solar cell protective sheet having the configuration shown in FIG. 1 was obtained.

Example 4
In Example 1, as the olefin resin of the thermoplastic resin layer, the same as in Example 1 except that a polyethylene resin having a density of 905 kg / m ³ (trade name: LumiTac 43-1 manufactured by Tosoh Corporation) was used. Operation was performed to obtain a solar cell protective sheet having the configuration shown in FIG.

Example 5
In Example 1, 50 parts by mass of a polyethylene resin having a density of 905 kg / m ³ (manufactured by Tosoh Corporation, trade name: Lumitac 43-1) as an olefin resin of the thermoplastic resin layer and a density of 895 kg / m ³ The same operation as in Example 1 except that a blend of 50 parts by mass of polyethylene resin (manufactured by Sumitomo Chemical Co., Ltd., trade name: Excellen EUL731-M) (density of blend resin: 900 kg / m ³ ) was used. The solar cell protective sheet having the configuration shown in FIG. 1 was obtained.

Example 6
In Example 1, as the olefin resin of the thermoplastic resin layer, a polyethylene resin having a density of 915 kg / m ³ (manufactured by Tosoh Corporation, trade name: LumiTac 54-1) was used. Operation was performed to obtain a solar cell protective sheet having the configuration shown in FIG.

Example 7
In Example 1, as the olefin resin of the thermoplastic resin layer, the same as Example 1 except that a polyethylene resin having a density of 900 kg / m ³ (manufactured by Tosoh Corporation, trade name: LumiTac 22-6) was used. Operation was performed to obtain a solar cell protective sheet having the configuration shown in FIG.

Example 8
In Example 1, 50 parts by mass of a polypropylene resin (manufactured by Prime Polymer Co., Ltd., trade name: Prime Polypro F-744NP) having a density of 890 kg / m ³ as an olefin resin of the thermoplastic resin layer and a density of 905 kg / m ³ The same operation as in Example 1 except that 50 parts by mass of polyethylene resin (trade name: Lumitac 43-1, manufactured by Tosoh Corporation) was blended (the density of the blended resin: 898 kg / m ³ ). The solar cell protective sheet having the configuration shown in FIG. 1 was obtained.

[Comparative Example 1]
In Example 1, as the olefin resin of the thermoplastic resin layer, the same operation as in Example 1 except that a polyethylene resin having a density of 918 kg / m ³ (manufactured by Nippon Polyethylene Co., Ltd., trade name: Novatec LC605Y) was used. The solar cell protective sheet having the configuration shown in FIG. 1 was obtained.

[Comparative Example 2]
In Example 1, 70 parts by mass of a polypropylene resin having a density of 922 kg / m ³ (trade name: Petrocene 204, manufactured by Tosoh Corporation) and a polyethylene resin having a density of 895 kg / m ³ are used as the olefin resin of the thermoplastic resin layer. (Tosoh Corporation, trade name: Excellen EUL 731-M) The same operation as in Example 1 was carried out except that 30 parts by mass (blend resin density: 914 kg / m ³ ) was used. A solar cell protective sheet having the structure shown in FIG. 1 was obtained.

[Comparative Example 3]
In Example 1, as the olefin resin of the thermoplastic resin layer, the same as Example 1 except that a polyethylene resin having a density of 870 kg / m ³ (trade name: TAFMER P-0180, manufactured by Mitsui Chemicals, Inc.) was used. The solar cell protective sheet having the configuration shown in FIG. 1 was obtained.

[Comparative Example 4]
In Example 1, 65 parts by mass of polyethylene resin having a density of 918 kg / m ³ (manufactured by Nippon Polyethylene Co., Ltd., trade name: Novatec LC605Y) and ethylene having a density of 930 kg / m ³ were used as the olefin resin of the thermoplastic resin layer. -Butyl acrylate copolymer resin (manufactured by Arkema, trade name: LOTLYL 30BA02) 35 parts by mass (blend resin density: 922 kg / m ³ ) Operation was performed to obtain a solar cell protective sheet having the configuration shown in FIG.

[Test Example 1] <Measurement of heat of fusion>
About the olefin resin which comprises the thermoplastic resin layer in an Example and a comparative example, the measurement of a calorie | heat amount is measured on condition of the following using a differential scanning calorimeter (the TI instrument company make, model number: Q2000). And data was collected.
-Sample adjustment conditions Heating was performed from -40 ° C to 250 ° C at a heating rate of 20 ° C / min.
Measurement conditions After holding at 250 ° C. for 5 minutes, the sample was cooled to −40 ° C. at a temperature drop rate of 20 ° C./min, and the change in the amount of heat was measured.
The area of the peak accompanying solidification was calculated from the obtained data, and this was defined as the heat of fusion ΔH (J / g). The results are shown in Table 1.

[Test Example 2] <Density measurement>
About the olefin resin which comprises the thermoplastic resin layer in an Example and a comparative example, the density ( kg / m < ³ > ) was measured according to JISK7112. When measuring a blend of two or more kinds of resins, after kneading at 210 ° C. with a biaxial kneader (manufactured by Toyo Seiki Seisakusho Co., Ltd., product name: Labo Plast Mill) and quenching in a water bath Measurements were again made on the pellets processed again. The results are shown in Table 1.

[Test Example 3] <MFR measurement>
About the olefin resin which comprises the thermoplastic resin layer in an Example and a comparative example, based on JISK7210: 1999, using a flow tester (made by Shimadzu Corporation, product name: CFT-100D), a load of 2.16 kg, MFR (g / 10 min) was measured at a test temperature of 190 ° C. The results are shown in Table 1.

[Test Example 4] <Measurement of curl amount>
The protective sheet for a solar cell produced in the example or the comparative example was cut into a 300 mm × 300 mm square, placed on a horizontal table, and the vertical distance (mm) from the table surfaces at the four corners was measured. The average value of each distance of the obtained four places was calculated, and this was taken as the curl amount (mm). The results are shown in Table 1.

[Test Example 5] <Blocking evaluation>
The protective sheet for a solar cell produced in the example or the comparative example was wound 100 m on a paper tube having a diameter of 3 inches and a width of 350 mm to produce an evaluation sample. The evaluation sample was stored in an atmosphere of 40 ° C. for one week, and then the situation when it was unwound again was evaluated according to the following criteria. The results are shown in Table 1.
○: Can be unwound without resistance.
Δ: Can be unwound but partially blocked, leaving a blocking mark on the sheet surface.
X: Blocking occurs partially or entirely, and unwinding is not possible.

  As can be seen from Table 1, the solar cell protective sheet of the example satisfying the conditions of the present invention had a small curl amount and no blocking problem.

  The solar cell protective sheet according to the present invention is suitably used as a back sheet of a solar cell module, for example.

DESCRIPTION OF SYMBOLS 1 ... Protective sheet for solar cells 11 ... Base material 12 ... Thermoplastic resin layer 13 ... Fluorine resin layer 14 ... Deposition layer 15 ... Adhesion layer 16 ... Metal sheet 2 ... Solar cell 3 ... Sealing material 4 ... Glass plate 10 ... Solar cell module

Claims (7)

A solar cell protective sheet comprising a substrate and a thermoplastic resin layer laminated on at least one surface of the substrate,
The thermoplastic resin layer is mainly composed of an olefin resin having a density of 875 to 920 g / m ³ and a heat of fusion ΔH obtained by a differential scanning calorimeter of 100.0 J / g or less. Protection sheet for solar cells.   The said olefin resin contains 60-100 mass% of ethylene as a monomer unit, The protective sheet for solar cells of Claim 1 characterized by the above-mentioned.   The solar cell protective sheet according to claim 1, wherein the thermoplastic resin layer is formed by extrusion coating.   The said thermoplastic resin layer is a single layer, The protection sheet for solar cells as described in any one of Claims 1-3 characterized by the above-mentioned.   The said thermoplastic resin layer is a layer adhere | attached with the sealing material which comprises a solar cell module, The protective sheet for solar cells as described in any one of Claims 1-4 characterized by the above-mentioned. A method for producing a protective sheet for a solar cell, comprising: a base material; and a thermoplastic resin layer laminated on at least one surface of the base material,
A thermoplastic resin composition mainly composed of an olefin resin having a density of 880 to 915 g / m ³ and a heat of fusion ΔH obtained by a differential scanning calorimeter of 100.0 J / g or less is at least of the substrate. A method for producing a protective sheet for a solar cell, comprising subjecting one surface to extrusion coating to form the thermoplastic resin layer. A solar battery module comprising a solar battery cell, a sealing material for sealing the solar battery cell, and a protective sheet laminated on the sealing material,
The protective sheet is a solar cell protective sheet according to claim 5,
The said protection sheet is adhere | attached on the said sealing material through the said thermoplastic resin layer, The solar cell module characterized by the above-mentioned.

Images