JP2010232294A - Protective sheet for solar cell module and solar cell module - Google Patents

Abstract

Provided is a protective sheet for a solar cell module, which can improve water vapor barrier properties as compared with a conventional sheet.
A protective sheet for a solar cell module, wherein a gas barrier layer made of aluminum nitride is laminated on at least one surface of a base sheet, and a fluororesin layer is laminated on the other side of the base sheet or the gas barrier layer.
[Selection] Figure 1

Description

  The present invention relates to a surface protection sheet for a solar cell module, a back surface protection sheet, and a solar cell module including the same.

A solar cell module, which is a device that converts solar light energy into electrical energy, has attracted attention as a system that can generate power without discharging carbon dioxide. The solar cell module is required to have high power generation efficiency and durability that can withstand long-term use even when used outdoors.
The main configuration of the solar cell module is a photovoltaic cell that is a photovoltaic element, a sealing material that is an electrical insulator that seals the solar cell, and a light receiving surface side (front surface side) and a back surface side of the sealing material, respectively. It consists of the provided surface protection sheet and back surface protection sheet, and these protection sheets prevent the permeation of water vapor into the solar cell module. Such a protective sheet for a solar cell module is required to have excellent water vapor barrier properties and weather resistance. In particular, with the rapid progress of related technologies such as the development of thin film solar cells, solar cell module protective sheets are required to have better water vapor barrier properties.
Conventionally, as a technique for improving water vapor barrier properties and weather resistance as a protective sheet for a solar cell module, for example, a technique disclosed in Patent Document 1 has been proposed.

Patent Document 1, is used as the protective layer of the solar cell module, silicon oxide on the surface (silica) is a sheet containing a fluororesin film layer including a thin film, the oxygen permeability of the sheet is 5 cc / m ² · day · atm or less, water vapor transmission rate of 5 g / m ² · day or less, light transmittance of 80% or more, silica thin film thickness of 150 to 500 mm, and adhesion strength of the film of 200 g / 15 mm or more A protective sheet for a solar cell module is disclosed.

JP-A-10-308521

  However, the conventional sheet on which the silica thin film is formed has insufficient water vapor barrier properties, and it is difficult to satisfy the water vapor barrier performance required for future protective sheets for solar cell modules.

  This invention is made | formed in view of the said situation, and aims at provision of the protection sheet for solar cell modules which can improve water vapor | steam barrier property compared with the conventional sheet | seat.

  In order to achieve the above object, the present invention provides a protective sheet for a solar cell module, wherein a gas barrier layer made of aluminum nitride is laminated on at least one surface of a base sheet.

  In the solar cell module protective sheet of the present invention, it is preferable that a fluororesin layer is laminated on the other surface of the base sheet or the gas barrier layer.

  In the solar cell module protective sheet of the present invention, the fluororesin layer may include titanium dioxide.

  In the protective sheet for a solar cell module of the present invention, it is preferable that an adhesive layer made of a heat-adhesive resin is laminated.

  In the protective sheet for a solar cell module of the present invention, the gas barrier layer is formed on the base sheet by a reactive sputtering method using aluminum as a target in an inert gas atmosphere containing nitrogen gas. Is preferred.

  The present invention also provides a solar cell module in which the protective sheet for a solar cell module is bonded to one or both of the front surface and the back surface.

Since the back surface protection sheet for solar cell modules of the present invention has a gas barrier layer made of aluminum nitride laminated on at least one surface of the base material sheet, it has a water vapor barrier property as compared with a sheet on which a conventional silica thin film is formed. Can be improved.
Moreover, the back surface protection sheet for solar cell modules of this invention can improve electrical insulation compared with the sheet | seat in which the conventional silica thin film was formed.

Since the solar cell module of the present invention is formed by adhering the protective sheet for solar cell module according to the present invention to the front or back surface of the module, it has excellent water vapor barrier properties and weather resistance, and can be used outdoors for a long period of time. It will be durable.
Moreover, the electrical insulation of a solar cell module can be improved by adhere | attaching the said sheet | seat with high electrical insulation.

It is sectional drawing of 1st Embodiment of the protection sheet for solar cell modules of this invention. It is sectional drawing of 2nd Embodiment of the protection sheet for solar cell modules of this invention. It is sectional drawing of 3rd Embodiment of the protection sheet for solar cell modules of this invention. It is sectional drawing of 4th Embodiment of the protection sheet for solar cell modules of this invention. It is a schematic block diagram of the solar cell module of this invention. It is a schematic block diagram of the reactive sputtering apparatus used for the film-forming of aluminum nitride.

FIG. 5 is a schematic configuration diagram of a solar cell module using the solar cell module protective sheet (hereinafter abbreviated as a protective sheet) of the present invention.
As illustrated in FIG. 5, the configuration of the solar cell module 50 includes a solar cell 40, a sealing material 30 covering the solar cell 40, and a surface fixed to the surface (light-receiving surface) side of the sealing material 30. The protection sheet 10 and the back surface protection sheet 20 fixed to the back surface (back surface) side of the sealing material 30 are included. In order to give the solar cell module the weather resistance and durability that can withstand long-term use outdoors and indoors, the solar cell 40 and the sealing material 30 are protected from wind and rain, moisture, dust, mechanical impact, etc. It is necessary to keep the inside of the solar cell module sealed from the outside air. For this reason, the protective sheet is required to have a high water vapor barrier property.

  FIG. 1 is a cross-sectional view of a first embodiment of the protective sheet of the present invention. 1 and FIGS. 2 to 4 described later exemplify the case where the protective sheet of the present invention is applied as the back surface protective sheet 20, but the protective sheet of the present invention is also applicable as the surface protective sheet 10. Needless to say. In the following description, an aluminum-deposited PET sheet is used for the base sheet 21, a coating liquid composition in which a white pigment such as titanium dioxide is added to the fluororesin layer 23, or the fourth embodiment shown in FIG. When the Al layer 25 is laminated as described above, it is intended to be applied to the back surface protective sheet 20, and when applied as the front surface protective sheet 10, the protective sheet seems to have sufficient transparency. A transparent base sheet is used, and a transparent protective sheet may be formed without adding the white pigment or laminating the Al layer 25.

  The protective sheet 20 </ b> A of the present embodiment has a configuration in which a gas barrier layer 22 made of an aluminum nitride thin film is laminated on one surface of a substrate sheet 21 and a fluororesin layer 23 is laminated on the other surface of the substrate sheet 21. ing.

  As the resin sheet that can be used as the base material sheet 21, those generally used as a resin sheet in a protective sheet for a solar cell module can be used. For example, polyethylene, polypropylene, polystyrene, polymethyl methacrylate, polytetrafluoroethylene, polyamide (nylon 6, nylon 66), polyacrylonitrile, polyvinyl chloride, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate Examples thereof include a sheet made of a polymer such as (PEN), polyoxymethylene, polycarbonate, polyphenylene oxide, polyester urethane, poly m-phenylene isophthalamide, poly p-phenylene terephthalamide. Especially, the sheet | seat which consists of polyesters, such as PET, PBT, and PEN, is preferable, and a PET sheet is mentioned as a more preferable thing specifically.

  What is necessary is just to select as thickness of the said base material sheet 21 based on the electrical insulation which a solar cell system requires. For example, when the substrate sheet 21 is a resin sheet, the film thickness is preferably in the range of 10 to 300 μm. More specifically, when the substrate sheet 21 is a PET sheet, the thickness of the PET sheet is preferably in the range of 10 to 300 μm from the viewpoint of lightness and electrical insulation, The range of 200 μm is more preferable, and the range of 50 to 150 μm is more preferable.

The gas barrier layer 22 is a thin film made of aluminum nitride (AlN), and a part of the nitrogen (N) may be replaced with oxygen (O). In this embodiment, the gas barrier layer 22 is directly formed on one surface of the base sheet 21.
The film thickness of the gas barrier layer 22 is preferably 20 nm or more, and more preferably 30 nm or more. If the film thickness is less than 20 nm, the water vapor barrier property of the protective sheet 20A is lowered.

  For example, the gas barrier layer 22 is formed by sputtering in an inert gas atmosphere using a substance mainly containing aluminum nitride (AlN) as a target, or by using aluminum (Al) as a target as shown in FIG. A film can be formed on one surface of the substrate sheet 21 by a reactive sputtering method in an inert gas atmosphere containing nitrogen gas and a small amount of oxygen gas.

  FIG. 6 is a schematic configuration diagram of a reactive sputtering apparatus for performing the reactive sputtering. Reactive sputtering using this reactive sputtering apparatus is performed as follows. First, a target 77 made of aluminum (Al) is placed on the cathode 74 in the vacuum chamber 71, and the base material 76 (base material sheet 21) is set on the anode 75 provided to face the cathode 74. Next, the inside of the vacuum chamber 71 is evacuated by the vacuum pump 72, and the supply gas 80 may contain a mixed gas of inert gas (mainly argon gas) and nitrogen gas (or nitrogen gas together with a trace amount of oxygen gas). ) Is introduced into the vacuum chamber 71 between the electrodes 74 and 75 by applying a voltage from the DC high-voltage power source 73 to the target 77 by using the glow discharge obtained by applying glow discharge to the plasma 77. , The target 77 is decomposed into molecular or atomic level fragments 81 which are blown off and condensed on the substrate 76 to form a film 79. At this time, by using the mixed gas as the supply gas 80, the sputtered Al reacts with nitrogen, and the produced aluminum nitride is deposited as a film 79.

  Here, the aluminum nitride of the formed film 79 may not have a stoichiometric composition component (AlN) but may have a non-stoichiometric composition component (AlxNy). Furthermore, when a small amount of oxygen gas is mixed in the mixed gas of inert gas and nitrogen gas as the mixed gas, a film having a composition in which a part of nitrogen of aluminum nitride is replaced by oxygen is obtained. Can do.

  As mentioned above, although the case where the gas barrier layer 22 was formed by reactive sputtering was described, the film formation method of the gas barrier layer 22 is not limited only to reactive sputtering, but the bipolar sputtering method, the tripolar sputtering method, Other film forming methods such as an electrode sputtering method, an RF sputtering method, a magnetron sputtering method, an ion beam sputtering method, a vacuum evaporation method, a plasma CVD method, an MOCVD method, and a laser evaporation method can also be used.

  The fluororesin layer 23 laminated on the other surface of the base sheet 21 is not particularly limited as long as it does not impair the effects of the present invention and contains fluorine. For example, the sheet | seat which has a fluorine-containing polymer may be sufficient, and the coating film which apply | coated the coating liquid which has a fluorine-containing polymer may be sufficient. From the viewpoint of making the fluororesin layer 23 thinner in order to reduce the weight of the protective sheet, a coating film coated with a coating solution having a fluorine-containing polymer is preferable.

As the sheet having the fluorine-containing polymer, for example, a sheet obtained by processing a polymer mainly composed of polyvinyl fluoride (PVF), ethylene chlorotrifluoroethylene (ECTFE), or ethylene tetrafluoroethylene (ETFE) into a sheet shape is preferable. As mentioned. As the polymer containing PVF as a main component, Tedlar (trade name) manufactured by DuPont can be used. Moreover, as a polymer having ECTFE as a main component, Halar (trade name) manufactured by Solvay Solexis can be used. As the polymer containing ETFE as a main component, Fluon (trade name) manufactured by Asahi Glass Co., Ltd. can be used.
The thickness of the sheet having a fluorine-containing polymer is generally preferably in the range of 5 to 200 μm, more preferably in the range of 10 to 100 μm, and most preferably in the range of 10 to 50 μm from the viewpoint of weather resistance and weight reduction.

The coating liquid having the fluorine-containing polymer is not particularly limited as long as it can be applied by being dissolved in a solvent or dispersed in water.
The fluorine-containing polymer contained in the coating liquid is not particularly limited as long as it is a polymer containing fluorine without impairing the effects of the present invention, but dissolved in the solvent (organic solvent or water) of the coating liquid, Those that can be crosslinked are preferred.
The fluorine-containing polymer is a polymer of a fluorine-containing monomer and other monomers copolymerizable with a fluorine-containing monomer that is optionally used.
Examples of the fluorine-containing monomer include vinyl fluoride (VF), vinylidene fluoride (VdF), chlorotrifluoroethylene (CTFE), tetrafluoroethylene (TFE), hexafluoropropylene, and fluorinated vinyl ether. These fluorine-containing monomers can be used alone or in combination of two or more.
Examples of other monomers include vinyl acetate, vinyl propionate, butyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl caproate, vinyl versatate, vinyl laurate, vinyl stearate, vinyl cyclohexylcarboxylate, and benzoic acid. Examples thereof include vinyl esters of carboxylic acids such as vinyl, alkyl vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, butyl vinyl ether and cyclohexyl vinyl ether, hydroxybutyl vinyl ether, and isobutylene. These monomers can be used alone or in combination of two or more.
Examples of fluorine-containing polymers include polymers of fluoroolefins having a curable functional group such as a hydroxyl group, and specific examples thereof include copolymers comprising TFE, isobutylene, VdF, hydroxybutyl vinyl ether and other monomers, and Preferred examples include copolymers comprising TFE, VdF, hydroxybutyl vinyl ether and other monomers.

  Preferable examples of the fluorine-containing polymer include chlorotrifluoroethylene such as LUMIFLON (trade name) manufactured by Asahi Glass Co., Ltd., CEFRAL COAT (trade name) manufactured by Central Glass Co., Ltd., and FLUONATE (trade name) manufactured by DIC Corporation. Polymers based on (CTFE), polymers based on tetrafluoroethylene (TFE) such as ZEFFLE (trade name) manufactured by Daikin Industries, Ltd., Zonyl (trade name) manufactured by DuPont, Examples thereof include polymers having a fluoroalkyl group such as Unidyne (trade name) manufactured by Daikin Industries, Ltd., and polymers having a fluoroalkyl unit as a main component. 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 more preferable. Among them, the LUMIFLON (trade name) and the ZEFFLE (trade name) are preferable. Most preferred.

The LUMIFLON (trade name) is an amorphous polymer containing CTFE, several kinds of specific alkyl vinyl ethers (VE), and hydroxyalkyl vinyl ethers as main structural units. A polymer having a monomer unit of hydroxyalkyl vinyl ether, such as LUMIFLON (trade name), is preferable because it is excellent in solvent solubility, crosslinking reactivity, substrate adhesion, pigment dispersibility, hardness, and flexibility.
The ZEFFLE (trade name) is a copolymer of TFE and an organic solvent-soluble hydrocarbon monomer (which may contain oxygen), and in particular, the copolymer has a highly reactive hydroxyl group. Is preferable because it is excellent in solvent solubility, cross-linking reactivity, substrate adhesion, and pigment dispersibility.

  Examples of the fluorine-containing polymer comprising a plurality of fluorine-containing monomers include Dyneon THV (trade name; manufactured by 3M), which is a terpolymer of VdF, TFE, and hexafluoropropylene. Such a multi-polymer is preferable because it can impart the properties of each monomer to the polymer. For example, the Dyneon THV (trade name) 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 liquid preferably contains fine particles of titanium dioxide as an inorganic pigment in addition to the fluorine-containing polymer. If necessary, a crosslinking agent, a crosslinking accelerator, a solvent, other pigments and an inorganic filler Etc. can also be included.

  The titanium dioxide contained in the coating solution is not particularly limited as long as it does not impair the effects of the present invention, but the dispersion in the fluororesin layer 23 is good, a high reflectance is obtained, and the durability is excellent. What can form the fluororesin layer 23 is preferable, and specific examples include trade name “Ti-Pure R105” (manufactured by DuPont), which is a rutile-type titanium dioxide that has been coated and surface-treated.

The crosslinking agent contained in the coating solution is not particularly limited as long as it does not impair the effects of the present invention, and metal chelates, silanes, isocyanates, and melamines are preferably used. By blending a crosslinking agent, the resulting coating film is cured, and weather resistance and scratch resistance can be improved. However, when it is assumed that the protective sheet is used outdoors for 30 years or more, the weather resistance is improved. From the viewpoint, aliphatic isocyanates are preferable as the crosslinking agent.
Examples of the crosslinking accelerator contained in the coating liquid include tin dibutyl dilaurate and tin dioctyl dilaurate, which are used to promote the crosslinking reaction between the fluorine-containing polymer and isocyanate.

  The solvent contained in the coating solution is not particularly limited as long as the effects of the present invention are not impaired. 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 can be preferably used. Among these, from the viewpoint of solubility of the components contained in the coating liquid and low persistence in the coating film (low boiling point temperature), the solvent is any one or more of xylene, cyclohexanone, and MEK. It is more preferable that it has.

  Furthermore, examples of other pigments and inorganic fillers contained in the coating liquid include silica, mica, boron nitride, zinc oxide, and aluminum oxide. As a specific example of silica, a trade name “CAB-O-SIL TS 720” (manufactured by Cabot Corporation), which is a hydrophobic silica in which a hydroxyl group on the silica surface is modified by a surface treatment of dimethyl silicone, can be exemplified as a preferable example.

  The composition of the coating liquid is not particularly limited as long as the effects of the present invention are not impaired, but preferably includes 3 to 120 parts by mass of titanium dioxide with respect to 100 parts by mass of the fluorine-containing polymer, and 10 to 100 parts by mass. More preferably. Moreover, although the solid content concentration of a coating liquid is not specifically limited, Usually, it is about 10-80 mass%.

As a method of applying the coating liquid on the other surface side of the substrate sheet 21 or on the gas barrier layer, it can be performed by a known method, and for example, it may be applied by a bar coater so as to have a desired film thickness. .
The film thickness of the fluororesin layer 23 formed by curing the coating liquid is not particularly limited, and may be, for example, a film thickness of 5 μm or more. From the viewpoint of water vapor barrier properties, weather resistance, and lightness, the thickness of the fluororesin layer 23 is preferably 5 to 100 μm, more preferably 8 to 50 μm, and even more preferably 10 to 30 μm.
The temperature in the drying process of the applied coating solution may be a temperature that does not impair the effects of the present invention, and is in the range of about 50 to 150 ° C. from the viewpoint of reducing the influence on the base sheet 21. Is preferred.

Since the protective sheet 20A of this embodiment has a gas barrier layer 22 made of aluminum nitride laminated on one surface of a base sheet 21, a conventional silica thin film is formed as demonstrated in the examples described later. Water vapor barrier properties can be improved as compared with the sheet.
Moreover, this protective sheet 20A can improve electrical insulation compared with the sheet | seat in which the conventional silica thin film was formed.

FIG. 2 is a cross-sectional view showing a second embodiment of the protective sheet of the present invention.
The protective sheet 20 </ b> B of the present embodiment has a configuration in which a gas barrier layer 22 and a fluororesin layer 23 are laminated in this order on one surface of a base sheet 21.
The details of the base sheet 21, the gas barrier layer 22, and the fluororesin layer 23 can be the same as those of the base sheet 21, gas barrier layer 22, and fluororesin layer 23 in the first embodiment described above.

The protective sheet 20B of the present embodiment includes the gas barrier layer 22 made of aluminum nitride and the fluororesin layer 23 containing titanium dioxide on one surface of the base material sheet 21, and thus the first embodiment described above. Almost the same effect can be obtained.
In the present embodiment, since the fluororesin layer 23 is laminated on the surface of the gas barrier layer 22, even if the base sheet 21 that does not easily adhere to the fluororesin layer 23 is used, the adhesion of the fluororesin layer 23 by the gas barrier layer is used. Therefore, the degree of freedom in selecting the material of the base material sheet 21 can be expanded, and the peeling of the fluororesin layer 23 can be prevented over a long period of time.

FIG. 3 is a cross-sectional view showing a third embodiment of the protective sheet of the present invention.
In the protective sheet 20C of this embodiment, a gas barrier layer 22 made of an aluminum nitride thin film is laminated on one surface of the base sheet 21, a fluororesin layer 23 is laminated on the other surface of the base sheet 21, and the gas barrier The adhesive layer 24 is laminated on the surface of the layer 22.
The details of the base sheet 21, the gas barrier layer 22, and the fluororesin layer 23 can be the same as those of the base sheet 21, gas barrier layer 22, and fluororesin layer 23 in the first embodiment described above.

  As the adhesive layer 24, from the viewpoint of improving the adhesion with the sealing material 30 when the protective sheet 20C is laminated on the solar cell module 50, an acrylic urethane resin, an ethylene-vinyl acetate copolymer (EVA), Polyvinyl butyral (PVB), an ethylene-methacrylic acid copolymer, an ionomer resin in which molecules of an ethylene-methacrylic acid copolymer are crosslinked with metal ions, and the like can be used. Furthermore, it is preferable to have thermal adhesiveness so that it can be thermally bonded to the sealing material 30. Here, thermal adhesiveness is a property that develops adhesiveness by heat treatment. As temperature in this heat processing, it is the range of 50-200 degreeC normally. From the viewpoint of having thermal adhesiveness, the adhesive layer 24 is selected from the group consisting of ethylene-vinyl acetate copolymer (EVA), ethylene-methacrylic acid copolymer (EMAA), ionomer resin, and mixtures thereof. One resin is preferable. Generally, the sealing material 30 is often a sealing resin made of EVA, and in this case, the sealing material 30 and the adhesive layer are formed by the adhesive layer 24 being a resin made of a polymer mainly composed of EVA. Adhesion with 24 can be improved.

  The thickness of the adhesive layer 24 is not particularly limited as long as the effects of the present invention are not impaired. More specifically, when the base resin of the adhesive layer 24 is EVA, the thickness is preferably in the range of 10 to 200 μm from the viewpoint of lightness and electrical insulation, and 20 to 150 μm. More preferably, it is the range.

Other polymers and various compounding agents may be added to the adhesive layer 24 as necessary.
Moreover, as various compounding agents, any of an organic compound and an inorganic compound may be sufficient, and the compounding agent normally used in the resin industry is used. For example, anti-aging agents, stabilizers, pigments such as titanium dioxide, flame retardants, plasticizers, crystal nucleating agents, hydrochloric acid absorbers, antistatic agents, inorganic fillers, lubricants, antiblocking agents, and ultraviolet absorbers are used.

  In this embodiment, when the adhesion between the gas barrier layer 22 and the adhesive layer 24 is inferior, a laminating adhesive layer is provided between these layers, and the gas barrier layer 22 is bonded to the gas barrier layer 22 via the adhesive layer. The layer 24 may be bonded. Examples of the adhesive used for the laminate adhesive layer include acrylic adhesives, urethane adhesives, silicone adhesives, epoxy adhesives, ester adhesives, and the like. These adhesives may be used individually by 1 type, and may be used in combination of 2 or more type.

The protective sheet 20 </ b> C of the present embodiment has a configuration in which a gas barrier layer 22 made of an aluminum nitride thin film is laminated on one surface of a substrate sheet 21 and a fluororesin layer 23 is laminated on the other surface of the substrate sheet 21. Since it is a thing, the effect similar to the protection sheet of 1st Embodiment mentioned above can be acquired.
Further, the protective sheet 20C of this embodiment has good thermal adhesiveness with the sealing material 30 on the back surface of the solar cell module 50 by providing the adhesive layer 24 made of EVA or the like on the surface of the gas barrier layer 22. Since the protective sheet 20C can be firmly bonded and fixed, a solar cell module having excellent durability can be configured.

FIG. 4 is a sectional view showing a fourth embodiment of the protective sheet of the present invention.
The protective sheet 20D of the present embodiment has a gas barrier layer 22, a laminating adhesive layer 26, an aluminum (Al) layer 25, a laminating adhesive layer 26, and an adhesive layer 24 in that order on one surface of the base sheet 21. While being laminated, the fluororesin layer 23 is laminated on the other surface of the base sheet 21.
The details of the base sheet 21, the gas barrier layer 22, and the fluororesin layer 23 can be the same as those of the base sheet 21, gas barrier layer 22, and fluororesin layer 23 in the first embodiment described above. Examples of the adhesive used for the laminating adhesive layer 26 include acrylic adhesives, urethane adhesives, silicone adhesives, epoxy adhesives, and ester adhesives. These adhesives may be used individually by 1 type, and may be used in combination of 2 or more type.

The Al layer 25 is formed in order to further improve the water vapor barrier property of the protective sheet 20D, and the thickness thereof is not particularly limited as long as the water vapor barrier property improving effect can be exhibited, but is usually in the range of 1 μm to 100 μm. It is.
The method of forming the Al layer 25 is not particularly limited. For example, the Al layer 25 can be formed by bonding an aluminum foil to the surface of the gas barrier layer 22 via a laminating adhesive layer 26, or on the surface of the gas barrier layer 22. It is also possible to form a film directly without the adhesive layer 26 for laminating by a method such as vacuum deposition.

  The protective sheet 20D of the present embodiment can obtain substantially the same effect as the protective sheet 20C of the third embodiment described above, and can further improve moisture resistance by laminating the Al layer 25.

  In the protective sheet of the present invention, a gas barrier layer made of aluminum nitride may be provided on both surfaces of the base sheet. By providing the gas barrier layer on both surfaces of the base sheet, the gas barrier property is further improved.

As shown in FIG. 5, the solar cell module of the present invention is the protective sheet described above so that the fluororesin layer is on the outer side of the sealing material 30 on the front surface (light receiving surface) or back surface (back surface) of the solar cell module 50. Any one of 20A, 20B, 20C, and 20D is bonded.
The type and structure of the solar cell module 50 are not particularly limited, and examples thereof include amorphous silicon (a-Si) solar cells, single crystal silicon (c-Si) solar cells, microcrystalline silicon (μc-Si) solar cells, and GaAs. It can be set as a compound semiconductor type solar cell and a dye-sensitized solar cell.

Since the solar cell module of the present invention is formed by adhering the protective sheets 20A, 20B, 20C, and 20D according to the present invention to the front surface or the back surface of the module, it has excellent water vapor barrier properties and weather resistance, and can be used for a long time outdoors. It will be durable enough to withstand use.
In addition, by adhering the sheet having high reflectivity to the back surface, the light that escapes to the back surface side through the gap between the solar cells in the solar cell module is reflected and returned to the solar cell side to increase the power generation efficiency. be able to.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further in detail, this invention is not limited to a following example at all. In addition, the thickness (film thickness) of the gas barrier layer (aluminum nitride, silica) of an Example and a comparative example was measured using "XP-1" by a stylus type | formula level | step difference surface and shape measuring apparatus (Ambios TECHNOLOGY).

[Example 1]
(Preparation of coating solution)
120 parts by mass of methyl ethyl ketone, 18.2 parts by mass of hydrophobic silica (trade name “CAB-O-SIL TS-720” manufactured by Cabot), 100 parts by mass of titanium dioxide (trade name “Ti-Pure R105” manufactured by DuPont) The pigment dispersion was prepared using a pigment disperser (manufactured by Tokushu Kika Kogyo Co., Ltd., apparatus name “TK Homodisper”).
Subsequently, to 87 parts by mass of the obtained pigment dispersion, 100 parts by mass of a chlorotrifluoroethylene copolymer (manufactured by Asahi Glass Co., Ltd., trade name “LUMIFLON LF200”, solid content concentration 60% by mass), aliphatic isocyanate -Based crosslinking agent (curing agent) (manufactured by Sumika Bayer Urethane Co., Ltd., trade name “Sumijoule N3300”, solid content concentration 100% by mass) 10.7 parts by mass, crosslinking accelerator (manufactured by Toyo Ink Manufacturing Co., Ltd., trade name) “BXX3778-10”, tin dioctyl dilaurate, solid concentration 2.5 mass%) was mixed at a ratio of 0.004 parts by mass and 110 parts by mass of methyl ethyl ketone to prepare a coating liquid containing titanium dioxide and a fluororesin. .

(Gas barrier layer deposition)
On one side of a 125 μm-thick PET film (trade name “MELINEX-S”, manufactured by Teijin DuPont Films Ltd.), which is a base material sheet, reactive sputter deposition is performed under the following conditions using the reactive sputtering apparatus shown in FIG. A gas barrier layer made of aluminum nitride having a thickness of 30 nm was formed.
Deposition conditions:
Plasma generation gas: Argon, nitrogen Gas flow rate: Argon 100 sccm, Nitrogen 30 sccm
Target material: Al
Power value: 2500W
Vacuum chamber internal pressure: 0.2Pa

(Formation of fluororesin layer)
Next, on the surface of the PET film on which the gas barrier layer is formed, the coating solution is applied using a bar coater so that the thickness of the dry coating film is 13 μm, and dried at 120 ° C. for 1 minute. A fluororesin layer was formed to produce the protective sheet of Example 1.

[Example 2]
A protective sheet of Example 2 was obtained in the same manner as Example 1 except that the thickness of the gas barrier layer was 50 nm.

[Example 3]
A protective sheet of Example 3 was obtained in the same manner as Example 2 except that the flow rate of nitrogen gas was 20 sccm.

[Example 4]
A protective sheet of Example 4 was obtained in the same manner as Example 2 except that the flow rate of nitrogen gas was 60 sccm.

[Example 5]
A protective sheet of Example 5 was obtained in the same manner as Example 1 except that the thickness of the gas barrier layer was 100 nm.

[Example 6]
A protective sheet of Example 6 was obtained in the same manner as in Example 1 except that the thickness of the gas barrier layer was 50 nm, and the coating liquid was not applied and the fluororesin layer was not formed.

[Comparative Example 1]
In the reactive sputter deposition, the same operation as in Example 1 was performed except that the target material was changed to Si, and oxygen gas was used instead of nitrogen gas in the plasma generation gas. A silicon oxide (silica) film was formed, and the coating liquid was applied to the surface on which the silica layer was formed using a bar coater so that the thickness of the dry coating film was 13 μm. Was dried for 1 minute to form a fluororesin layer, and a protective sheet of Comparative Example 1 was produced.

[Comparative Example 2]
A fluororesin layer was formed in the same manner as in Example 1 without forming a gas barrier layer made of aluminum nitride, and a protective sheet of Comparative Example 2 was produced.

[Comparative Example 3]
Only the PET film having a thickness of 125 μm as the base sheet was used as the protective sheet of Comparative Example 3.

Water vapor permeability and electrical insulation (dielectric breakdown strength) were measured for each of the protective sheets of Examples 1 to 6 and Comparative Examples 1 to 3 prepared as described above.
These measurements were performed as follows. The measurement results are summarized in Table 1.

<Measurement of water vapor transmission rate>
The protective sheet obtained in Examples 1 to 6 and Comparative Examples 1 to 3 penetrates from the fluororesin layer side (however, Example 6 is the gas barrier layer side and Comparative Example 3 is one side of the PET film). The amount of water vapor (water vapor permeability) was measured.
Specifically, according to the standard of ISO 15106-1: 2003, a moisture permeability sensor method (trade name “L80” manufactured by PBI Dunsensor Co., Ltd.) is used according to a humidity sensor method under the conditions of a temperature of a transmission cell of 40 ° C. and a relative humidity difference of 90%. -5000 ").

<Dielectric breakdown strength>
In accordance with JIS C2110 “Test Method for Dielectric Strength of Solid Electrical Insulating Material”, the dielectric breakdown strength [unit: kV / mm] of each protective sheet obtained in Examples 1-6 and Comparative Examples 1-3 It was measured.
The voltage application method was in accordance with a short-time destructive test.
The electrode shape was a φ25 mm disc / φ25 mm disc.
The measurement was performed in an environment of 23 ° C. and 50% RH.

From the results of Table 1, the protective sheets of Examples 1 to 6 having an aluminum nitride thin film as a gas barrier layer have a water vapor permeability of less than half compared to the protective sheet of Comparative Example 1 having a gas barrier layer made of silica (SiO ₂ ). It can be seen that excellent water vapor barrier properties can be obtained.
The protective sheet of Example 1-6, the silica compared to the protective sheet of Comparative Example 1 having a gas barrier layer formed of (SiO _2), has a higher dielectric breakdown strength, is excellent in electrical insulation properties .

  The protective sheet of the present invention is useful as a protective sheet for solar cell modules because it has a high water vapor barrier property and an excellent electrical insulating property as compared with conventional protective sheets.

DESCRIPTION OF SYMBOLS 10 ... Surface protective sheet 20 ... Back surface protective sheet 20A, 20B, 20C, 20D ... Protective sheet 21 ... Base material sheet 22 ... Gas barrier layer 23 ... Fluororesin layer 24 ... Adhesive layer 25 ... Al layer 26 ... Adhesive layer 30 for lamination ... Sealing material 40 ... Solar battery cell 50 ... Solar battery module

Claims (6)

  A protective sheet for a solar cell module, wherein a gas barrier layer made of aluminum nitride is laminated on at least one surface of a base sheet.   The protective sheet for a solar cell module according to claim 1, wherein a fluororesin layer is laminated on the other surface of the base sheet or the gas barrier layer.   The protective sheet for a solar cell module according to claim 2, wherein the fluororesin layer contains titanium dioxide.   The protective sheet for a solar cell module according to any one of claims 1 to 3, wherein an adhesive layer made of a heat-adhesive resin is laminated.   5. The gas barrier layer according to claim 1, wherein the gas barrier layer is formed on the base sheet by a reactive sputtering method using aluminum as a target in an inert gas atmosphere containing nitrogen gas. The protection sheet for solar cell modules of Claim 1.   The solar cell module in which the protection sheet for solar cell modules of any one of Claims 1-5 is adhere | attached on one or both of the surface and a back surface.

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