TWI565088B - Protective backsheet for solar cell and solar cell module - Google Patents

Description

Solar cell back protection sheet and solar cell module

The present invention relates to a solar cell back surface protective sheet comprising a weather resistant flame retardant resin layer, an easy adhesive layer and a plastic film. Furthermore, the present invention relates to a solar cell module using the solar cell back protective sheet.

In recent years, due to the increased awareness of environmental issues, solar cells, which are clean energy sources without environmental pollution, have attracted attention and are being researched and put into practical use based on the use of solar energy as a useful energy resource. There are various forms of solar cell elements, and as a representative thereof, a crystalline germanium solar cell element, a polycrystalline germanium solar cell element, an amorphous germanium solar cell element, a copper indium selenide solar cell element, and a compound are known. Semiconductor solar cell components, etc.

In the solar cell module, the simple form is a configuration in which a filler and a glass plate are sequentially stacked on both surfaces of the solar cell element. The glass plate is excellent in transparency, weather resistance, and abrasion resistance, and is now generally used as a sealing sheet on the light receiving side of the sun. However, in the non-light-receiving side where transparency is not necessary, the company is continuing to develop solar cell back protective sheets other than glass sheets due to cost, safety, and processability considerations (hereinafter, also referred to as "back protection sheets"). ) to replace the glass plate.

The back protective sheet may, for example, be a single-layer film such as a polyester film; or a sheet of a vapor-deposited layer of a metal oxide or a non-metal oxide provided on a polyester film or the like, or a laminated polyester film or a fluorine-based film, A multilayer film of a film such as an olefin film or an aluminum foil (Patent Documents 1 to 3).

In order to improve dimensional stability, Patent Document 4 has proposed thickness A back protective sheet having a fluorine-containing resin sheet having a specific structure of 30 μm or less. Further, in order to improve the water vapor barrier property and obtain the bending resistance, Patent Document 5 proposes to laminate a gas barrier layer composed of tantalum nitride and a back surface protective sheet of a fluororesin layer on the substrate sheet. In another example in which a fluorine-based resin sheet is used, Patent Document 6 discloses a sheet obtained by forming an aziridine group-containing conjugated resin layer on a film formed of a fluorine-containing resin or a non-fluorine-containing resin having a specific structure. . Further, in order to achieve weather resistance, heat resistance, color retention, adhesion between a layer and an encapsulating material, and scratch resistance, Patent Document 7 proposes to use a back surface protective sheet of an amorphous fluoropolymer.

Patent Document 8 proposes a back protective sheet which is a plastic film substrate, an adhesive layer, a water vapor barrier layer, a resin containing a vinyl copolymer (A), a polyisocyanate compound (B), and a polyester (C). A back protective sheet in which a light-resistant resin formed of a composition is laminated. Further, Patent Document 8 proposes a laminated sheet which is a laminated sheet in which an outer layer sheet (back surface protective sheet or front sheet) and a sealing resin are laminated and integrated. It has been described that the use of the polyphenylene ether-based resin layer as an outer layer sheet is excellent in durability, flame retardancy, and dimensional stability, and the adhesion to the sealing resin layer is favorably maintained, and the workability can be improved.

Further, it has been proposed to provide a coating layer containing a phosphorus-based or inorganic-based flame retardant in a thermoplastic resin film which is not flame-retardant, and has a UL equivalent to the US UNDERWRITERS LABORATORIES company specification (hereinafter, abbreviated as UL). A laminated film of a flame retardant degree of HB and V-2 specified in 94 is proposed for use in a so-called solar cell (Patent Documents 10 to 14).

Patent Document 15 discloses a sealing material disposed between a power generating element and a back surface protective sheet, which satisfies the Japanese Building Standards Act The flame retardancy described in Article 109 No. 1. Specifically, it discloses a sealing material formed using a sealing material composition containing a polyolefin resin and flame retardant particles in the range of 0.1% by weight to 10% by weight. Further, in order to satisfy the constitution of the UL-94 HB specification, Patent Document 16 discloses a configuration in which a solar cell sealing film containing an ethylene vinyl acetate copolymer and an organic peroxide contains an ethylene vinyl acetate copolymer. The phosphazene compound having a specific structure is 0.1 to 30 parts by mass in terms of 100 parts by mass. Further, in the constitution of the flame retardancy which satisfies the fire prevention and disaster prevention regulations according to the Japanese Building Standards Law, Patent Document 17 discloses a solar battery module which is an insulator layer, an insulating intermediate layer, a solar battery, and a covering material. The organic resin intermediate layer is laminated in this order, and a fluororesin layer covering the insulating intermediate layer, the solar cell, and the organic resin intermediate layer is further laminated. Further, the covering material is composed of a material in which a solvent-soluble fluororesin is blended in an organic resin layer having flammability in a fluororesin, and an example in which a phosphazene compound is blended is disclosed.

Further, in the case of a coating material which imparts flame retardancy to a solar cell back surface protective sheet, although it is a patent document which is disclosed after the application of the priority application, the patent document has proposed an inorganic material in a fluorine resin. A coating agent for a pigment and a flame retardant, and it is described that it satisfies the HB specification of UL-94 (Patent Document 18).

[Previous Technical Literature]

[Patent Literature]

[Patent Document 1] JP-A-2004-200322

[Patent Document 2] JP-A-2004-223925

[Patent Document 3] JP-A-2001-119051

[Patent Document 4] JP-A-2003-347570

[Patent Document 5] JP-A-2010-219196

[Patent Document 6] JP-A-2004-352966

[Patent Document 7] Japanese Patent Publication No. 2010-519742

[Patent Document 8] JP-A-2008-098592

[Patent Document 9] JP-A-2011-146671

[Patent Document 10] JP-A-2009-179037

[Patent Document 11] JP-A-2010-89334

[Patent Document 12] JP-A-2010-120321

[Patent Document 13] JP-A-2010-149447

[Patent Document 14] JP-A-2010-234741

[Patent Document 15] JP-A-2011-134986

[Patent Document 16] JP-A-2011-114118

[Patent Document 17] Japanese Patent Publication No. 06-196742

[Patent Document 18] JP-A-2011-162598

A variety of proposals have been made so far for the high performance of solar cell modules. In order to achieve a flame retardancy, a method of using a fluorine-based resin for a member such as a sealing material or a back surface protective sheet, or a film containing a flame retardant for a thermoplastic resin film has been proposed.

The flammability of a general polymer material is evaluated by the HB test or the V (VTM) test specified in UL-94 above, from the time of ignition to the time of fire suppression. In the above conventional examples, a laminated film which satisfies the HB-defined HA-94 and the flame retardancy of V-2 has been proposed. However, the specifications of the flammability of the solar cell module and the solar cell back protective sheet are specified to be the standard specifications of the solar cell. IEC61730-1, IEC61730-2 and UL-1703, in which the solar cell back protective sheet meets the flame spread test (radiant panel test, ASTM E162) specified in UL-1703 is required by the market. The flame spread test is a flame spread obtained by (i) combustion temperature (heat release factor), (ii) combustion speed (≒ flame diffusion coefficient), which is the basis for evaluating the flame spread coefficient, and after the fire is extinguished The HB test or V (VTM) test evaluated at the time is not the same.

In order to improve the flame retardancy, the method of using a glass plate for the back surface protection member is effective, but as described above, the material other than the glass plate is being replaced by cost, safety, and workability. Therefore, it is an important subject to provide a back surface protection sheet that satisfies UL-1703 in the solar cell back surface protection sheet. In addition to the flame retardancy, the solar cell module is also required to withstand long-term heat and humidity resistance under outdoor harsh conditions and excellent long-term outdoor weather resistance. Furthermore, in order to accelerate the spread of solar cell modules, it is important to provide them inexpensively.

In view of the above background, the present invention provides a flame retardancy having characteristics satisfying the flame spread test prescribed in UL-1703, and is excellent in long-term heat and humidity resistance and long-term outdoor weather resistance, and is inexpensively provided. A solar cell back protective sheet and a solar cell module using the solar cell back protective sheet.

In order to achieve the above object, the present inventors have continued to study the results of the present invention, and have found that the following aspects can solve the problems of the present invention and complete the present invention. In other words, the solar cell back surface protective sheet of the present invention comprises a weather-resistant flame-retardant resin layer (1) having a film thickness t (μm), a plastic film (2), and an easy-adhesive layer (3). , the aforementioned solar battery back The surface on one side of the surface protection sheet is composed of the weather resistant flame-retardant resin layer (1). Further, the other surface of the solar cell back surface protective sheet is composed of the above-mentioned easy-adhesive layer (3). Further, the weather-resistant flame-retardant resin layer (1) contains a phosphorus-based flame retardant (A) selected from the group consisting of a phosphazene compound, a phosphinic acid compound, and (poly)phosphoric acid melamine, and is selected from the group consisting of fluorine. a weather resistant resin (B) composed of a resin, a urethane resin, and a polyester resin, wherein the film thickness t of the weather resistant flame retardant resin layer (1) is the total film thickness of the solar cell back surface protective sheet In the range of 2.5 to 20%, the total phosphorus concentration from the phosphorus-based flame retardant (A) in the weather-resistant flame-retardant resin layer (1) is 2.1 to 14.2% by weight.

The phosphorus-based flame retardant (A) in the weather-resistant flame-retardant resin layer (1) preferably contains 20 to 50% by weight. The phosphorus-containing flame retardant (A) from the weather-resistant flame-retardant resin layer (1) preferably has a total phosphorus concentration of 3 to 10% by weight. The weather-resistant resin (B) is preferably a fluorine-based resin or an oligomer-based polyester resin having an intrinsic viscosity of 0.6 (dl/g) or more and a cyclic trimer content of 1% by weight or less.

The solar cell module of the present invention includes a solar cell surface sealing sheet (I) located on the light receiving surface side of the solar cell, a sealing material layer (II) located on the light receiving surface side of the solar cell, and a solar cell element (III). a solar cell module in which the sealant layer (IV) on the non-light-receiving surface side of the solar cell and the solar cell back surface protective sheet (V) adjacent to the non-light-receiving surface side sealant layer (IV) are The weather-resistant flame-retardant resin layer (1) constituting the solar cell back surface protective sheet is located farthest from the solar cell surface sealing sheet (I).

According to the present invention, it is possible to have an excellent effect, which can provide a A solar cell back protective sheet that satisfies the flame retardancy characteristic of UL-1703 and has excellent long-term heat and humidity resistance and long-term outdoor weather resistance, and is inexpensively provided, and uses the solar cell back protective sheet Solar battery module.

Hereinafter, the present invention will be described in detail. Further, as long as the object of the present invention is met, it is needless to say that other embodiments may fall within the scope of the present invention. In addition, in the present specification, the description of the arbitrary number A to the arbitrary number B is larger than the range A and the number B is smaller.

The solar cell back protective sheet is as described above and is required to meet the flame spread test specified in UL-1703. In addition, the life of solar cell modules is now required to be guaranteed for 15 to 25 years. The long-term weather resistance and long-term heat and humidity resistance of solar cell back protection sheets are also necessary. Furthermore, the solar cell back protective sheet is also required to satisfy the withstand voltage.

From the viewpoint of ensuring the withstand voltage, the film thickness of the solar cell back surface protective sheet may vary depending on the thickness of the material or the sealing material to be formed, but it is preferably 250 μm or more. Moreover, from the viewpoint of flexibility, productivity, and cost of the solar cell back surface protective sheet, it is preferably a thickness of 400 μm or less. Moreover, it is also important to provide a solar cell back protective sheet inexpensively. Among them, it is preferable to increase the ratio of the thickness of the plastic film (2) mainly constituting the member of the solar cell back surface protective sheet while preventing the combustion of the entire solar cell back surface protective sheet from expanding, and achieving fire resistance or fire extinguishing property. From this point of view, when the thickness of the solar cell back surface protective sheet is in the range of 250 to 400 μm, the thickness of the plastic film (2) is preferably in the range of 125 to 250 μm. Also, the material of the plastic film (2) is not It is particularly limited, but a thermoplastic resin such as a polyester film or an olefin film is preferable from the viewpoint of inexpensive supply.

As a result of continuous intensive research by the present inventors, it has been surprisingly found that the flame retardancy which satisfies the characteristics of the flame spread test specified in UL-1703 can be found by satisfying the following composition (i) to (v). The solar cell back protective sheet is excellent in long-term heat and humidity resistance, long-term outdoor weather resistance, and excellent voltage resistance.

(i) The solar cell back surface protective sheet of the present invention comprises a weather-resistant flame-retardant resin layer (1) having a film thickness t (μm), a plastic film (2), and an easy-adhesive layer (3).

(ii) In the solar cell back surface protective sheet, the outermost layer disposed on the solar cell element side is an easy-adhesive layer (3), and the other outermost layer is a weather-resistant flame-retardant resin layer (1).

(iii) The weather resistant flame-retardant resin layer (1) contains weather resistance selected from the group consisting of a phosphazene compound, a phosphinic acid compound, and a group selected from the group consisting of a fluorine resin, a urethane resin, and a polyester resin. Resin (B).

(iv) The film thickness t of the weather resistant flame-retardant resin layer (1) is 2.5 to 20% of the total film thickness of the solar cell back surface protective sheet.

(v) The total phosphorus concentration from the phosphorus-based flame retardant (A) in the weather-resistant flame-retardant resin layer (1) is 2.1 to 14.2% by weight.

The above (i) to (v) will be described in detail below.

The solar cell back surface protective sheet of the present invention is provided at a low cost by satisfying (i) to (iii) while achieving weather resistance and flame retardancy, and can maintain good adhesion in the solar cell module. In the method of imparting flame retardancy, a method of adding a flame retardant to the entire solar cell back protective sheet or separately providing a flame retardant layer and a weather resistant layer may be considered. While a method of adding a flame retardant to the intermediate layer is used, the present invention employs a weather-resistant resin from the outermost layer farthest from the solar cell element, and a flame retardant is added thereto. The weather-resistant flame-retardant resin layer (1) is external to the inside of the solar cell back protective sheet to further protect the solar cell module from ultraviolet rays or physical smashing. Therefore, the deterioration of the output of the solar cell element can be suppressed, and the adhesion to the inner layer of the solar cell back surface protective sheet can be improved. This result can further confirm the effect of flame retardancy.

Incidentally, as the flame retardant to be generally used, a phosphorus-based flame retardant, a nitrogen-based flame retardant, a bismuth-based flame retardant, an inorganic flame retardant, and the like can be exemplified.

In the case of a phosphorus-based flame retardant, melamine phosphate, melamine polyphosphate, strontium phosphate, strontium polyphosphate, ammonium phosphate, ammonium polyphosphate, ammonium amide ammonium phosphate, ammonium polyphosphate ammonium phosphate, urethane phosphate can be exemplified. a phosphate-based compound or a polyphosphate-based compound such as a polyphosphate urethane, a red phosphorus, an organic phosphate compound, a phosphazene compound, a phosphonic acid compound, a phosphinic acid compound, a phosphine oxide compound, or a phosphorane. A compound, a phosphoamide compound, or the like.

As the nitrogen-based flame retardant, a triazine-based compound such as melamine, melam, meleme, melome, melamine cyanurate or the like can be exemplified. , a cyanuric acid compound, an isomeric cyanuric acid compound, a triazole compound, a tetrazole compound, a diazo compound, urea, etc.: in the case of a lanthanum flame retardant, a polyoxygen compound or a decane compound or the like.

The halogen-based flame retardant may, for example, be a halogenated compound of a halogenated bisphenol A, a halogenated epoxy compound, a halogenated phenoxy compound or the like. , halogenated oligomer or polymer, and the like.

Examples of the inorganic flame retardant include metal hydroxides such as aluminum hydroxide, magnesium hydroxide, zirconium hydroxide, barium hydroxide, and calcium hydroxide, tin oxide, aluminum oxide, magnesium oxide, zirconium oxide, and oxidation. Zinc, molybdenum oxide, cerium oxide, nickel oxide, zinc carbonate, magnesium carbonate, calcium carbonate, barium carbonate, zinc borate, hydrated glass, and the like.

There are many types of flame retardants as shown in the above examples. Among the many flame retardants, the inventors have continuously studied the results to find (iii) a phosphorus-based flame retardant (A) of any one of a phosphazene compound, a phosphinic acid compound, and a (poly)phosphoric acid melamine. Useful.

First, the reason why the flame retardant other than the above (iii) is not suitable will be explained. In order to exhibit a flame retardancy effect, a nitrogen-based flame retardant or an inorganic flame retardant is required to increase the amount of the flame retardant to be added. Along with this, there is a problem that the weather resistance or the moist heat resistance of the weather-resistant flame-retardant resin layer (1) is greatly reduced. Further, since the halogen-based flame retardant is subjected to the damp heat resistance test or the weather resistance test, the weather-resistant flame-retardant resin layer is largely yellowed, so that it is avoided in appearance consideration. Moreover, in the weather resistance test, there is a problem that the flame retardant promotes deterioration of the weather resistant resin (B).

Further, the phosphorus-based flame retardant is preferable in that it exhibits flame retardancy with a relatively small addition amount, but is, for example, (poly)ammonium phosphate or (poly)phosphoric acid amine used for a flexible printed circuit board or the like. The formate is slowly decomposed by the passage of the heat and humidity resistance test to produce phosphoric acid which is a strong acid, which is not preferable. The produced phosphoric acid becomes a hydrolysis catalyst of the weather-resistant resin (B), and the weather-resistant flame-retardant resin layer (1) is largely deteriorated. Therefore, even if it is a phosphorus-based flame retardant, it is not preferable that the flame retardant which hydrolyzes in the heat-resistant test to generate an acid is not preferable.

The phosphorus-based flame retardant (A) of the present invention can effectively exhibit flame retardancy in a small amount of addition to the extent that weather resistance or moist heat resistance is not affected. Further, it is excellent in a point where no acid is generated by hydrolysis. Further, the phosphorus-based flame retardant (A) itself has high moist heat resistance, and hardly hydrolyzes when subjected to moist heat. Therefore, it is possible to effectively prevent the occurrence of a decrease in the adhesion of the weather-resistant flame-retardant resin layer (1) to the inner layer such as the plastic film (2). In other words, by using the phosphorus-based flame retardant (A) of the present invention, the heat-resistant property is further improved than when the weather-resistant resin (B) is a monomer, and the adhesion with time is favorably maintained, in addition to the flame retardant. In addition to the effect, it is considered that the effect is lowered (i) the combustion temperature (heat release factor), and (ii) the combustion rate (≒ flame diffusion coefficient) is lowered.

Among the phosphorus-based flame retardants (A), in particular, the phosphazene compound and the phosphinic acid compound are highly hydrophobic and highly filler-like compounds, so that by using these compounds, the weather resistance and flame retardancy can be more effectively improved. The hydrophobicity of the resin layer (1). That is, it is possible to further exhibit high moist heat resistance even when the weather resistant resin (B) monomer is used. Therefore, it is very suitable as a flame retardant for solar cell back protection sheets.

As the phosphazene compound, a phosphazene oligomer exemplified in the following general formula (1) or (2) can be exemplified.

Wherein, in the general formula (1) or (2), each of R ¹ and R ² is a hydrogen atom or a halogen-free monovalent organic group ^; and the monovalent organic group of R ¹ and R ² represents a phenyl group, an alkyl group, The amine group, the allyl group, the aforementioned phenyl group and the like may each further have a halogen-free substituent. As the substituent, it may be suitably selected from the group consisting of a hydroxyl group, an amine group, a cyano group, and a nitro group. n is an integer from 3 to 10.

The above R ¹ or R ² is preferably a phenyl or alkyl cyclophosphazene, and the cyclophosphazene is preferably a tricyclic phosphazene. Specifically, a hexaalkyloxytricyclophosphazene or a hexaphenoxytricyclophosphazene, and a hexaphenoxytricyclophosphazene is preferred.

As the hexaalkyloxytricyclophosphazene, hexamethoxytricyclophosphazene, hexaethoxytricyclophosphazene, hexapropoxytricyclophosphazene or the like can be exemplified.

In the case of hexaphenoxytricyclophosphazene, in addition to the unsubstituted hexaphenoxytricyclophosphazene, a hexaphenoxytricyclophosphazene having a substituent such as a hydroxyl group or a cyano group can be exemplified.

As the phosphinic acid compound, the phosphinates exemplified in the following general formula (3) can be exemplified.

Wherein, in the general formula (3), R1 and R2 are the same or different, and are represented by a linear or branched alkyl group having 1 to 6 carbon atoms or an aryl group, and M represents at least one selected from the group consisting of Mg, A metal of a group consisting of Ca, Al, Sb, Sn, Ge, Ti, Zn, Fe, Zr, Ce, Bi, Sr, Mn, Li, Na, and K, and n is an integer of 1 to 4. As a preferable compound, a phosphinate in which M is Mg, Ca or Al, and an aluminum phosphinate in which M is Al is particularly preferable. Specifically, R1 and R2 are alkyl groups, n=3 paraxane Aluminium phosphinate is preferred.

In the case of (poly)phosphoric acid amide, a compound in which the phosphoric acid and melamine exemplified in the following general formula (4) are in a salt state can be exemplified. In the following general formula (4), n is preferably from 1 to 10, and when n is 2 or more, it is referred to as "melamine polyphosphate".

The above-mentioned phosphorus-based flame retardant (A) may be used singly or in combination of a plurality of compounds in each compound group, or may be arbitrarily combined from a plurality of compound groups.

The weather-resistant resin (B) is responsible for preventing the influence of deterioration due to ultraviolet rays or physical smashing, and acts as a binder, so that the phosphorus-based flame retardant (A) is not in the weather-resistant flame-retardant resin layer (1). Will agglutinate and exist uniformly.

The weather resistant resin (B) is suitably selected from the group consisting of a fluorine resin, a urethane resin, and a polyester resin. Examples of the urethane-based resin include a polyester polyurethane resin, a polyether polyurethane resin, a polycarbonate polyurethane resin, or an amine group other than the above polyester polyurethane resin. Acid ester resin. The urethane resin may also be a urethane urea resin having a urea bond on the above various urethane resins. In order to improve the weather resistance, an ultraviolet absorber, a light stabilizer, an antioxidant, or the like may be added to the weather resistant resin (B), and an ultraviolet absorber, a light stabilizer, an antioxidant, or the like may be added to the weather resistant resin (B).

A preferred fluorine-based resin for the weatherable resin (B) may be a direct connection The fluorine-bonded monomer (hereinafter also referred to as a fluorine-containing monomer) component in the carbon portion of the main chain contains 50 mol% or more and 100 mol% or less in the resin. Among them, a block copolymer containing a block containing no fluorine-containing monomer component is not preferable even if the fluorine-containing monomer is 50 mol% or more in total copolymerization. In other words, a portion of the carbon directly bonded to the main chain is bonded to a random copolymer of fluorine monomer, a fluorine-containing monomer and a non-fluorinated monomer are mutually copolymerized; or a plurality of copolymers of a fluorine-containing monomer, or The polymer containing a single fluoromonomer is in accordance with the fluororesin of the present invention.

Preferred examples of the fluorine-containing monomer include CHF=CH ₂ , CF ₂ =CH ₂ , CHF=CHF, CF ₂ =CHF, CF ₂ =CF ₂ , CFCl=CF ₂ , CF ₂ =CF-CF ₃ , CF ₂ =CF-CF ₂ CF ₃ , CF ₂ =CF-O-(CF ₂ CF ₂ ) _n -CF ₃ and the like.

Preferred fluorine-based resins for the weather-resistant resin (B) include polytetrafluoroethylene (PTFE), polychlorotrifluoroethylene (PCTFE), polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), and perfluoroalkane. An oxyfluororesin (PFA), a tetrafluoroethylene-hexafluoropropylene copolymer (FEP), an ethylene-tetrafluoroethylene copolymer (ETFE), an ethylene-chlorotrifluoroethylene copolymer (FCTFE), and the like.

The fluorine-based resin is excellent in weather resistance and chemical resistance, and can be preferably used as the weather-resistant resin (B). Since the fluorine-based resin composed of the above-mentioned fluorine-containing monomer does not have a urethane bond or an ester bond which is suspected of hydrolysis in the main chain, a trace amount of acid generated by the phosphorus-free flame retardant (A) is used as Catalyst causes hydrolysis problems for a long time. Therefore, it is more preferable than the urethane resin or the polyester resin. Further, in the case of using a urethane resin or a polyester resin, for example, when ammonium phosphate is used, ammonium phosphate is decomposed in a heat and humidity resistance test to produce a strong acid phosphoric acid. Therefore, since the produced phosphoric acid decomposes the urethane resin or the polyester resin, a flame retardant such as ammonium phosphate is not suitable for the solar cell back surface protective sheet.

A preferred polyester resin of the weather resistant resin (B) is obtained by reacting a carboxylic acid component having a carboxylic acid group with a hydroxyl component having a hydroxyl group.

Examples of the carboxylic acid component include benzoic acid, p-tert-butylbenzoic acid, phthalic anhydride, isophthalic acid, terephthalic acid, succinic anhydride, adipic acid, sebacic acid, and tetrahydrophthalic acid. Anhydride, hexahydrophthalic anhydride, maleic anhydride, fumaric acid, isaconic acid, tetrachlorophthalic anhydride, 1,4-cyclohexanedicarboxylic acid, trimellitic anhydride, methylcyclohexane Alkene tricarboxylic anhydride, pyrogalic anhydride, ε-caprolactone, fatty acid.

The above hydroxyl component is in addition to ethylene glycol, propylene glycol, 1,3-butylene glycol, 1,6-hexanediol, diethylene glycol, dipropylene glycol, neopentyl glycol, triethylene glycol, 3-methylpentane Examples of the diol component such as a diol or 1,4-cyclohexanedimethanol include glycerin, trimethylolethane, trimethylolpropane, trimethylolaminomethane, and pentaerythritol. A polyfunctional alcohol such as pentaerythritol.

As the weather resistant resin (B), a specific polyester resin can be used by polymerizing a carboxylic acid component and a hydroxyl component in accordance with a usual method. The polyester resin is preferably an oligomer polyester resin from the viewpoint of satisfying the combustion test (UL-1703, UL-94), weather resistance, and moist heat resistance.

The oligomer polyester resin has an intrinsic viscosity of 0.6 (dl/g) or more and a cyclic trimer content of 1% by weight or less. The intrinsic viscosity is preferably from 0.6 to 1.2 (dl/g). The intrinsic viscosity of the polyester resin is extrapolated to a concentration of 0 by dividing the specific viscosity (η sp = (η / η 0) -1) by the η sp / c of the concentration c (g / mL) of the resin in the solvent. The way to find. Where η 0 is the viscosity of the solvent, c (g/mL) is the concentration of the resin in the solvent, η is the viscosity of the resin solution in c (g/mL), and sp is the ratio of the viscosity of the resin solution to the viscosity of the solvent.

The content of the cyclic trimer of the polyester resin is preferably as small as possible, and more preferably 0.5% by weight or less. The cyclic trimer content of the polyester resin is The following method was carried out: 100 mg of a polyester resin was dissolved in 2 mL of o-chlorophenol, and the weight % was measured by a liquid chromatography method.

A preferred amine-based formic acid resin of the weather-resistant resin (B) is obtained by reacting a hydroxyl component other than the polyester resin having a hydroxyl group with an isocyanate compound.

As the hydroxyl component, a polymerizable polyol such as a polyether polyol obtained by adding polyethylene glycol, polypropylene glycol, ethylene oxide or propylene oxide, an acrylic polyol or a polybutadiene polyol can be used.

The above isocyanate compound may be the same as the polyisocyanate compound (C) described later. Examples thereof include propyl diisocyanate (TDI), exohexyl diisocyanate (HDI), methylene bis(4,1-phenylene) diisocyanate (MDI), and methyl 3-isocyanate-3,5. a diisocyanate such as 5-trimethylcyclohexyl isocyanate (IPDI) or benzoyl diisocyanate (XDI), or a trimethylolpropane adduct of such diisocyanates, or a terpolymer of such diisocyanates A trimeric isocyanate, a biuret combination of such a diisocyanate, a polymerizable diisocyanate or the like.

Further, when the weather resistant resin (B) requires higher toughness, weather resistance, and moist heat resistance, in order to obtain a higher crosslinking density, a reactive group can also be introduced into the side chain of the weather resistant resin (B). The functional group is crosslinked by a general crosslinking agent. The crosslinking agent may, for example, be a polyisocyanate compound, a polyglycidyl compound or a polyaziridine compound.

From the viewpoint of durability or coating stability, a curing agent having a polyester- or urethane-based resin having a hydroxyl group and a functional group reactive with an isocyanate hydroxyl group is preferably an isocyanate compound. From the viewpoint of further improving durability, a polyisocyanate compound is preferred.

Polyisocyanate compounds are used to make weatherable resins (B) to each other Cross-linking to form a weatherable resin layer which is strong and has stretchability, flexibility, moldability, abrasion resistance, long-term weather resistance, long-term heat and humidity resistance, and chemical resistance. In order to prevent the weather-resistant resin layer obtained from changing from yellow to brown over time, it is preferred to use only an alicyclic or aliphatic compound.

The alicyclic polyisocyanate compound may, for example, be isophorone diisocyanate, hydrogenated toluene diisocyanate or hydrogenated 4,4'-diphenylmethane diisocyanate.

The aliphatic polyisocyanate compound may, for example, be trimethylhexyl diisocyanate, exohexyl diisocyanate or isocyanuric acid diisocyanate.

Examples of the aromatic polyisocyanate compound include diphenylmethane diisocyanate, toluene diisocyanate, naphthalene-1,5-diisocyanate, o-xylene diisocyanate, m-xylene diisocyanate, and p-xylene diisocyanate. Triphenylmethane triisocyanate, polymethylpolyphenyl isocyanate, and the like.

As the polyisocyanate compound, a terminal isocyanate addition product, a biuret modified substance, or a trimer isocyanate modified product of a reaction product of the above compound and a diol or a diamine can also be used.

In particular, when the polyisocyanate compound contains a trimer isocyanate modified body, particularly a triisocyanate containing a trimeric isocyanate ring, a more weatherable and stretchable weather resistant resin layer can be obtained, which is preferable. Specific examples of the triisocyanate containing a trimeric isocyanate ring include a trimerized isocyanate modified isophorone diisocyanate (for example, Desmodur Z4470 manufactured by Sumitomo Bayer Co., Ltd.), and a trimeric isocyanate modified exohexyl diisocyanate (for example). For example, Sumitomo Bayer Carbamate Company Sumidur N3300), a trimeric isocyanate modified toluene diisocyanate (for example, Sumidur FL-2, FL-3, FL-4, HL BA manufactured by Sumitomo Bayer Co., Ltd.). Further, the trimer isocyanate ring may be further reacted with the polyester (c) having two or more reactive functional groups to increase the isocyanate group in one molecule, and the resulting urethane bond may further be combined with one equivalent. The isocyanate group reacts with allophanate, which in turn increases the isocyanate group in one molecule. As the polyester (c) having two or more functional groups reactive with an isocyanate group, a known polyester resin can be used.

Further, an isocyanate group of the above polyisocyanate compound may be used, for example, methanol, ethanol, n-pentanol, chlorohydrin, isopropanol, phenol, p-nitrophenol, m-cresol, acetamidineacetone, acetamidineacetic acid. A block modified body in which a block agent such as ethyl ester or ε-caprolactam is reacted and blocked.

Further, the polyisocyanate compound may also be a two-terminal isocyanate prepolymer obtained by reacting a polyester (d) having two or more functional groups reactive with an isocyanate group with a diisocyanate compound (e) having an isocyanate group at both terminals. . When the polyisocyanate compound contains the above-mentioned two-terminal isocyanate prepolymer, a small amount can be obtained, and the film is not impaired. One type of the polyisocyanate compound may be used, or two or more types may be used in combination.

As the polyester (d) having two or more functional groups reactive with an isocyanate group, a known polyester resin can be used. Examples of the diisocyanate compound (e) having an isocyanate group at both terminals include toluene diisocyanate, naphthalene-1,5-diisocyanate, o-toluene diisocyanate, diphenylmethane diisocyanate, and trimethylhexyl diisocyanate. Isophorone diisocyanate, 4,4'-diphenylmethane diisocyanate, hexyl diisocyanate, m-xylene Diisocyanate, p-xylene diisocyanate, quaternary acid diisocyanate, hydrogenated 4,4'-diphenylmethane diisocyanate, hydrogenated toluene diisocyanate, and the like.

Polyisocyanate compound For the weather resistant resin (B), the total number of isocyanate groups of the polyisocyanate compound is preferably 0.1 to the total number of functional groups (functional groups reactive with isocyanate groups) of the weather resistant resin (B). 5 times, more preferably 1 to 3 times. When the amount is less than 0.1 times, the crosslinking density is too low, and solvent resistance, abrasion resistance, and weather resistance are insufficient. When the ratio is more than 5 times, the isocyanate is excessive and reacts with moisture in the air to become The main reason for the change in seasonal physical properties.

The hardener may contain, in addition to the above polyisocyanate compound, a well-known oxazoline compound such as 2,5-dimethyl-2-oxazoline or 2,2-(1,4-butylene)-double. (2-oxazoline) or an anthraquinone compound, such as dioxonium isophthalate, diterpene sebacate, diammonium adipate.

The content of the aromatic ring in the weather resistant resin (B) is preferably at most 50% by weight and not more than 10% by weight, and it is preferred that the aromatic ring is not contained as much as possible. When the content of the aromatic ring in the weather-resistant resin (B) exceeds 50% by weight, ultraviolet rays are absorbed, and yellowing of the weather-resistant flame-retardant resin layer (1) and deterioration of the coating film are caused, and weather resistance is liable to lower.

Moreover, in order to improve the lubricity or barrier property of the surface, the weather-resistant flame-retardant resin layer (1) may be added with inorganic fine particles or organic fine particles.

Specific examples of the inorganic fine particles include vermiculite, glass fiber, glass powder, glass beads, clay, wollastonite, iron oxide, cerium oxide, lithopone, pumice powder, aluminum sulfate, and cerium. Inorganic particles such as zirconium acid, dolomite, and sand iron. Further, the inorganic fine particles may contain impurities to the extent that they do not impair their properties. . Further, the shape of the particles may be any shape such as a powder, a granule, a granule, a true spherical shape, a flat shape, or a fibrous shape.

Specific examples of the organic fine particles include polyolefin wax, polymethyl methacrylate resin, polystyrene resin, nylon resin, melamine resin, guanamine resin, phenol resin, urea resin, enamel resin, and acrylic acid. Polymer particles such as a methyl ester resin or an acrylate resin; or cellulose powder, nitrocellulose powder, wood powder, recycled paper powder, rice bran powder, starch, and the like. The organic fine particles can be obtained by a polymerization method such as an emulsion polymerization method, a suspension polymerization method, a dispersion polymerization method, a soap-free polymerization method, a seed polymerization method, or a microsuspension polymerization method. Further, the organic particles may contain impurities to the extent that they do not impair their properties. Further, the shape of the particles may be any shape such as a powder, a granule, a granule, a flat plate, or a fiber.

In addition, in the weather-resistant flame-retardant resin layer (1), in order to improve the strength of the weather-resistant flame-retardant resin layer to be obtained, various heats other than the weather-resistant resin (B) may be contained within a range that does not impair the effects of the present invention. Plastic resin. The thermoplastic resin may, for example, be polypropylene, polyethylene, ethylene-vinyl acetate copolymer, polyisobutylene, polybutadiene, polystyrene, polycarbonate, polymethylpentene, ionic polymer, acrylonitrile-butyl A diene-styrene resin, an acrylic resin, a polyvinyl alcohol, a polyamide resin, a polyacetal, an epoxy resin or the like.

The amount of the thermoplastic resin to be added is preferably 50 parts by weight or less, and more preferably 30 parts by weight or less based on 100 parts by weight of the total of the weather resistant resin (B). When it exceeds 50 parts by weight, the compatibility with other components may be lowered.

In the weather resistant flame-retardant resin layer (1), a pigment may be added for the purpose of coloring. The pigment can be used in the past, and carbon black, titanium oxide, or the like can be used. Inorganic pigments such as zinc oxide, lead oxide, zinc sulfide, zinc antimony or various organic pigments.

The phosphorus-based flame retardant (A), particles, and pigment are preferably mixed with a dispersion resin or a dispersing agent as needed to prepare a paste, and then mixed with a weather-resistant resin (B) or the like. The dispersion resin is preferably a weather-resistant resin (B) itself, but is not particularly limited, and a polar group having excellent pigment dispersibility, for example, a hydroxyl group, a carboxyl group, a thiol group, an amine group, a guanyl group, a ketone group or the like can be used. Acrylic resin, polyurethane resin, polyurea resin, polyester resin, and the like. Examples of the dispersant include a pigment derivative, an anionic surfactant, an amphoteric surfactant, a nonionic surfactant, a titanium coupling agent, a decane coupling agent, and the like. Further, the surface of the pigment may be modified by a metal chelating agent, a resin coating or the like.

The weather-resistant flame-retardant resin layer (1) of the present invention satisfies the above (iv) (v). That is, the film thickness t of the weather resistant flame-retardant resin layer (1) is 2.5 to 20% of the total film thickness of the solar cell back surface protective sheet. For example, when the solar cell back surface protective sheet having a film thickness of 300 μm, the film thickness t of the weather resistant flame-retardant resin layer (1) is in the range of 7.5 to 60 μm. Further, the total phosphorus concentration from the phosphorus-based flame retardant (A) in the weather-resistant flame-retardant resin layer (1) is 2.1 to 14.2% by weight. By setting the film thickness t of the weather-resistant flame-retardant resin layer (1) to the above range and setting the total phosphorus concentration to a specific range, it is possible to provide a solar cell back surface protective sheet which is excellent in flame retardancy and economy.

In terms of the thickness, by setting the film thickness t of the weather resistant flame-retardant resin layer (1) to 2.5% or more of the total film thickness of the solar cell back surface protective sheet, the plastic of the solar cell back surface protective sheet as the main constituent member can be suppressed. The combustion of the film (2) can meet the flame spread test of UL-1703. On the other hand, when the film thickness t of the weather resistant flame-retardant resin layer (1) is the back of the solar cell When the total film thickness of the face protection sheet is 20% or more, it becomes difficult to form a uniform layer, and it is more disadvantageous in terms of cost.

In addition, by setting the total phosphorus concentration from the phosphorus-based flame retardant (A) in the weather-resistant flame-retardant resin layer (1) to 2.1% or more, not only the flame retardancy of the coating film itself but also sufficient formation can be sufficiently maintained. The carbonized film is effective in suppressing the burning of the plastic film (2) or the like. As a result, the specification value of the flame spread test can be satisfied. Moreover, by setting the total phosphorus concentration to 14.2% or less, the weather resistance and the moist heat resistance can be favorably maintained. The preferred range of the total phosphorus concentration from the phosphorus-based flame retardant (A) in the weather-resistant flame-retardant resin layer (1) is from 3 to 10% by weight.

The weight of the phosphorus-based flame retardant (A) in the weather-resistant flame-retardant resin layer (1) is preferably 10% by weight or more, more preferably 15% by weight or more, and most preferably 20% by weight or more. Further, the weight of the phosphorus-based flame retardant (A) in the weather-resistant flame-retardant resin layer (1) is preferably 60% by weight or less, more preferably 50% by weight or less. By including the amount of the phosphorus-based flame retardant (A) in the range of 10% by weight or more and 60% by weight or less, flame retardancy, weather resistance, and moist heat resistance can be satisfactorily satisfied. In particular, by setting it as 20 weight% or more, it is effective to improve flame retardance. In addition, by setting the content of the weather resistant resin (B) to be appropriately 50% by weight or less, the weather resistance and the moist heat resistance can be more satisfactorily maintained.

The phosphorus-based flame retardant (A) selected from the phosphazene compound, the phosphinic acid compound, and the (poly)phosphoric acid melamine used in the present invention hardly hydrolyzes in the moisture heat resistance test. However, even if a very small amount of acid is produced as a result of a small amount of hydrolysis, the acid becomes a catalyst during a very long period of time, and the hydrolysis of the weather-resistant resin (B) is promoted, and the flame-retardant resin layer which promotes weather resistance is promoted (1) Debt doubts. Therefore, the weather resistant resin (B) is preferably not contained in the main chain of the resin. Hydrolyzable site.

Next, the plastic film (2) used in the present invention will be described. The plastic film (2) used in the present invention may be a polyester resin film such as polyethylene terephthalate, polybutylene terephthalate or polybutylene terephthalate; polyethylene, poly An olefin film of propylene, polycyclopentadiene or the like; a fluorine-based film of a polyfluorinated vinyl group, a polyvinylidene fluoride film, a polytetrafluoroethylene film, an ethylene-tetrafluoroethylene copolymer film, or the like; an acrylic film, triethylene hydride Cellulose film. From the viewpoint of film rigidity and cost, a polyester resin film is preferred, and a polyethylene terephthalate film is preferred. The plastic film (2) may be one layer or a multi-layer structure of two or more layers.

The plastic film (2) may be colorless and may also contain a coloring component such as a pigment or a dye. The method of containing a coloring component is, for example, a method of preliminarily kneading a coloring component when forming a film, a method of printing a coloring component on a colorless transparent film substrate, or the like. Further, the colored film may be used in combination with a colorless transparent film.

Next, the easy-adhesion layer (3) used in the present invention will be explained. The easy-adhesive layer (3) in the present invention is a layer for improving the adhesion between the plastic film (2) and the non-light-receiving surface side sealing material (IV), and is the most disposed on the surface side of the solar cell back surface protective sheet. The resin layer on the surface. Further, when the solar cell module is formed, the non-light-receiving side sealing material (IV) and the solar cell back surface protective sheet (V) of the present invention are bonded to the easy-adhesive layer (3), whereby The solar cell back protection sheet is mounted in the solar cell module.

The easy-adhesive layer (3) used in the present invention can be formed from a general adhesive containing various resins. Preferred examples thereof include a polyester resin. A urethane resin or an acrylic resin. The resin may be used singly or in combination of two or more. It is also possible to use such resins for compositing.

The preferred polyester resin as the easy adhesive layer (3) is also included in the polyester resin having a hydroxyl group in addition to the polyester resin in which the carboxylic acid component reacts with the hydroxyl component (esterification reaction, transesterification reaction). Further, a polyester polyurethane resin obtained by reacting with an isocyanate compound, or a polyester polyurethane polyurea resin obtained by further reacting with a diamine component.

The carboxylic acid component of the polyester resin constituting the easy adhesive layer (3) may, for example, be benzoic acid, p-tert-butylbenzoic acid, phthalic anhydride, isophthalic acid, terephthalic acid, succinic anhydride or the like. Diacid, sebacic acid, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, maleic anhydride, fumaric acid, isaconic acid, tetrachlorophthalic anhydride, 1,4-cyclohexane Alkanedicarboxylic acid, trimellitic anhydride, methylcyclohexenetricarboxylic anhydride, pyrogalic anhydride, ε-caprolactone, fatty acid.

The hydroxyl component of the polyester resin constituting the easy adhesive layer (3), in addition to ethylene glycol, propylene glycol, 1,3-butylene glycol, 1,6-hexanediol, diethylene glycol, dipropylene glycol, and neopentyl Examples of the diol component such as diol, triethylene glycol, 3-methylpentanediol, and 1,4-cyclohexanedimethanol include glycerin, trimethylolethane, and trimethylolpropane. A polyfunctional alcohol such as trimethylolaminomethane, neopentyltetraol or dipentaerythritol.

The adhesive layer (3) can be a specific polyester resin obtained by polymerizing a carboxylic acid component and a hydroxyl component according to a usual method.

The urethane-based resin of the easy-adhesive layer (3) is obtained by reacting a hydroxyl component other than the polyester resin having a hydroxyl group with an isocyanate compound.

As the above hydroxyl component, a polyether polyol to which polyethylene glycol, polypropylene glycol, ethylene oxide or propylene oxide is added, an acrylic polyol, or the like may be used. A polymeric polyol such as a polybutadiene-based polyol.

The above isocyanate compound may be the same as the polyisocyanate compound (C) described later. Examples thereof include propyl diisocyanate (TDI), exohexyl diisocyanate (HDI), methylene bis(4,1-phenylene) diisocyanate (MDI), and methyl 3-isocyanate-3,5. a diisocyanate such as 5-trimethylcyclohexyl isocyanate (IPDI) or benzoyl diisocyanate (XDI), or a trimethylolpropane adduct of such diisocyanates, or a terpolymer of such diisocyanates A trimeric isocyanate, a biuret combination of such a diisocyanate, a polymerizable diisocyanate or the like.

The monomer of the acrylic resin constituting the easy adhesive layer (3) is exemplified by the general formula (a) CH ₂ =CR ₁ -CO-OR ₂ (R ₁ represents a hydrogen atom or a methyl group, and R ₂ represents a hydroxyl group or a carbon number. Acrylic acid, methacrylic acid, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-hexyl acrylate, butyl acrylate, 2-ethylhexyl acrylate represented by a hydrocarbon group of 1 to 20 substituents , 4-hydroxybutyl acrylate, hydroxypropyl acrylate, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, butyl methacrylate, n-hexyl methacrylate, methacrylic acid Lauryl ester, 2-hydroxyethyl methacrylate, 4-hydroxybutyl methacrylate, hydroxypropyl methacrylate, and the like. Further examples are acrylamide, methacrylamide, acrylonitrile, methacrylonitrile, N-methylol acrylamide, N-alkyl alcohol acrylamide, diacetone acrylamide, diacetone methacryl Indoleamine, acrolein, methacrolein, glycidyl methacrylate, etc. are used as reactive monomers. The present invention can be used as a specific acrylic resin by copolymerizing these monomers in accordance with a conventional method.

In order to improve the toughness, stretchability, heat resistance, moist heat resistance, and weather resistance of the easy-adhesive layer (3), it is preferred to use an adhesive containing a crosslinking agent. When the non-light-receiving side sealing material (IV) is overlapped with the solar cell back surface protective sheet (V) of the present invention and bonded to form a solar cell module, the solar cell back surface protective sheet (V) is contained on the outermost surface. The easy adhesive layer (3) of the crosslinking agent is crosslinked. For example, when the polyester resin, the urethane resin, or the acrylic resin previously exemplified is used for the easy adhesive layer (3), the resin preferably has a hydroxyl group, a carboxyl group, a sulfonyl group, a phosphonium group, or the like. The reaction point of an isocyanate group, an epoxy group or the like.

The crosslinking agent may, for example, be a polyisocyanate compound, a polyglycidyl compound or a polyaziridine compound.

From the viewpoint of durability or coating stability, a curing agent having a functional group reactive with a polyester-based or urethane-based resin having a hydroxyl group and an isocyanate hydroxyl group is preferably an isocyanate compound. From the viewpoint of further improving durability, a polyisocyanate compound is preferred. Further, a blocked polyisocyanate compound can also be used. The polyisocyanate compound can be the same as the polyisocyanate compound exemplified as the crosslinking agent of the weather resistant resin (B).

The crosslinking agent may contain, in addition to the above polyisocyanate compound, a well-known oxazoline compound such as 2,5-dimethyl-2-oxazoline or 2,2-(1,4-butylene)- Bis(2-oxazoline) or anthraquinone compounds, such as dioxonium isophthalate, diterpene sebacate, diammonium adipate.

The solar cell back surface protective sheet may be provided with a water vapor barrier layer in order to impart moisture resistance. The water vapor barrier layer is not particularly limited, and examples thereof include a metal foil or a vapor deposited layer of a metal oxide or a non-metal inorganic oxide.

As the metal foil, an aluminum foil, an iron foil, a zinc plate or the like can be used. From the viewpoint of corrosion resistance, aluminum foil is preferable, and the thickness is preferably from 10 μm to 100 μm, more preferably from 20 μm to 50 μm. The two layers can be used to Various known adhesives are known.

The vapor deposition layer is provided on one surface of the plastic film (2). A single-sided vapor-deposited polyester film may be laminated with an interlayer adhesive layer interposed therebetween, or a single-sided vapor-deposited polyester film and another vapor-deposited film may be laminated via an interlayer adhesive layer.

As the vapor-deposited metal oxide or non-metal inorganic oxide, an oxide such as barium, aluminum, magnesium, calcium, potassium, tin, sodium, boron, titanium, lead, zirconium, hafnium or the like can be used. Further, a fluoride of an alkali metal or an alkaline earth metal or the like can also be used. These may be used alone or in combination. These metal oxides or non-metal inorganic oxides can be deposited by a conventionally known PVD method such as vacuum deposition, ion plating or sputtering, or a CVD method such as plasma CVD or microwave CVD.

The water vapor barrier layer may be a laminate in which two or more layers of the barrier layer are laminated in accordance with necessary electrical insulating properties or water vapor barrier properties.

A method of providing the weather resistant flame-retardant resin layer (1) or the easy-adhesive layer (3) on the plastic film (2) or the water vapor barrier layer may be exemplified by a roll coater, a die coater, and a roll coater. Conventional coating methods such as a bar coater, a gravure roll coater, a reverse roll coater, a dip coating method, a knife coater, a gravure coater, a micro gravure coater, and a slant wheel coater, and the weather resistance is difficult. a method of coating a flammable resin composition (1') or an easy-adhesive composition (3'), or a film formed of a weather-resistant flame-retardant resin composition (1') or an easy-adhesive composition (3') A method of laminating a plastic film (2) or a water vapor barrier layer by a conventionally known lamination method such as a dry buildup method, an extrusion buildup method, or a heat buildup method.

Next, a method of manufacturing the solar cell back surface protective sheet of the present invention will be described. 2A shows a weather resistant flame retardant resin layer (1), a plastic film (2) A schematic cross-sectional view showing an example of the solar cell back surface protective sheet of the present invention in which the adhesive layer (3) is laminated. The solar cell back surface protective sheet of the present invention may have a layer such as a water vapor barrier layer (4) and an interlayer adhesive layer (5). For example, FIG. 2B shows a laminate of a weather-resistant flame-retardant resin layer (1), a water vapor barrier layer (4), an interlayer adhesive layer (5), a plastic film (2), and an easy-adhesive layer (3). A schematic cross-sectional view of a solar cell backside protective sheet of the present invention. 2C shows a weather-resistant flame-retardant resin layer (1), a plastic film (2), an interlayer adhesive layer (5), a water vapor barrier layer (4), and an easy-adhesive layer (3). A schematic cross-sectional view of a solar cell backside protective sheet of the invention.

Next, a method of manufacturing the solar cell module of the present invention will be described. The solar cell module of the present invention is obtained by the solar cell surface sealing sheet (I) located on the light receiving surface side of the solar cell, the sealing material layer (II) on the light receiving surface side of the solar cell, and the solar cell element. (III), a sealing material layer (IV) on the non-light-receiving surface side of the solar cell, and a solar cell back surface protective sheet of the present invention as a detailed configuration layer, and the solar cell back surface protective sheet constituting the present invention The weather-resistant flame-retardant resin layer (1) is laminated in such a manner as to be farthest from the solar cell surface sealing sheet (I). In other words, the solar cell inner sealing sheet is laminated on the non-light-receiving side sealing material layer (IV) by being connected to the easy-adhesive layer (3) constituting the solar cell back surface protective sheet of the present invention, and the present invention can be obtained. Solar battery module. When the non-light-receiving side sealing material layer (IV) and the solar cell back surface protective sheet are laminated, the two are brought into contact under reduced pressure, and then it is preferable to carry out the superposition under heating and pressure. When the easy adhesive layer (3) is thermosetting, it may be returned to normal pressure and then placed under high temperature conditions to perform hardening of the easy adhesive layer (3).

[Examples]

Hereinafter, the present invention will be described in further detail by way of examples. In the examples, the parts represent parts by weight and the % means % by weight. Further, each symbol in the table is as follows.

Phosphorus-based flame retardant A1: Exolit OP935 (aluminum trisuccinate, manufactured by Clariant)

Phosphorus-based flame retardant A2: Exolit OP1230 (aluminum trisuccinate, manufactured by Clariant)

Phosphorus-based flame retardant A3: Exolit OP1312 (mixture of aluminum trisuccinate and melamine phosphate, manufactured by Clariant)

Phosphorus-based flame retardant A4: SPB-100 (phenoxycyclotriphosphazene, manufactured by Otsuka Chemical Co., Ltd.)

Phosphorus-based flame retardant A5: SPH-100 (4-hydroxyphenoxycyclotriphosphazene, manufactured by Otsuka Chemical Co., Ltd.)

Phosphorus-based flame retardant A6: FP-300 (4-cyanophenoxycyclotriphosphazene, manufactured by Fushimi Pharmaceutical Co., Ltd.)

Phosphorus-based flame retardant A7: PHOSMEL100 (melamine phosphate, manufactured by Hitachi Chemical Co., Ltd.)

Phosphorus-based flame retardant A8: PHOSMEL200 (melamine phosphate dimer, manufactured by Hitachi Chemical Co., Ltd.)

Phosphorus-based flame retardant A9: ammonium polyphosphate

Phosphorus-based flame retardant A10: Triphenyl phosphate (made by Daiba Chemical Industry Co., Ltd.)

Non-phosphorus flame retardant A11: STABIACE MC-55 (melamine cyanurate, manufactured by Nippon Chemical Industry Co., Ltd.)

Non-phosphorus flame retardant A12: aluminum hydroxide

Halogen-based flame retardant A13: Fire Cut FCP-83D (decabromodiphenyl oxide, manufactured by Suyu Chemical Co., Ltd.)

Fluorine-based resin B1: PVDF emulsion solution (manufactured by ARKEMA)

Fluorine-based resin B2: PVDF pellet (KYNAR, manufactured by ARKEMA)

Urethane resin B3: urethane resin solution (SANPRENE, manufactured by Sanyo Chemical Co., Ltd.)

Polyester resin B4: Polyester resin pellet (manufactured by Toyobo Co., Ltd., VYLON, intrinsic viscosity 0.52 (dl/g), cyclic trimer content: 1.5% by weight)

Polyester resin B5: Polyester resin pellet (VYLON, manufactured by Toyobo Co., Ltd.) was removed by a Soxler extractor (intrinsic viscosity: 0.67 (dl/g), cyclic trimer content: 0.5% by weight)

Acrylic resin B6: benzotriazole and a hydroxyl group-containing acrylic resin (HALS Hybrid UV-G720T solution manufactured by Nippon Shokubai Co., Ltd., hydroxyl value = 38).

TIPAQUE CR-97: Ishihara Industrial Co., Ltd., titanium oxide for white pigments <Production of weather-resistant flame retardant film (1~14, 101~102, 23, 25~31)>

The phosphorus-based flame retardant (A), the weather-resistant resin (B), and the pigment (C) are mixed at a solid component composition ratio shown in Table 1A and Table 1C, and then dissolved in 50/50 of toluene/ethyl acetate. The solvent was mixed and the solid content was made 50%. Then, it is dispersed by a paint shaker, and then a weather resistant flame retardant resin solution (1 to 14, 101 to 102, 23, 25 to 31) is obtained.

Applying the above-mentioned weather resistant flame retardant to an exfoliated polyethylene terephthalate (hereinafter referred to as SP-PET) by an applicator The resin solution (1 to 14, 101 to 102, 23, 25 to 31) was evaporated to obtain a coating film of 30 μm, and then peeled off from SP-PET to produce a weather-resistant flame-retardant film.

<Production of weather-resistant flame retardant film (15~22, 103~108, 32, 34~39)>

The phosphorus-based flame retardant (A), the weather-resistant resin (B), and the pigment (C) are mixed as a solid component shown in Tables 1B and 1C, and then a rolling machine (SKS50, manufactured by Shin-Rong Industrial Co., Ltd.) is used. Mix and practice. Subsequently, after kneading and pressing using a twin-screw extruder (manufactured by PLACON Co., Ltd., Japan), the pellet was cut by a pelletizer to obtain a pellet-shaped resin composition. Then, the resin composition obtained above was extruded into a sheet shape by a T-die extruder to prepare a weather-resistant flame-retardant film having a thickness of 30 μm.

<Combustibility measurement: UL test>

Weather resistant flame retardant films (1 to 23, 25 to 32, 34 to 39, and 101 to 108) having a thickness of 30 μm were evaluated in accordance with the HB or V specifications specified in UL-94.

<<HB specification>> A test piece in which a strip-shaped test piece is placed horizontally, and one end portion is in contact with the fire of the burner to cause combustion, and the speed at which the combustion is performed is judged to be acceptable. In the case of a weather-resistant flame-retardant film having a thickness of 30 μm, the burning rate is 40 mm/min or less, or 75 mm/min or less, which is "qualified" for the HB test.

<<VSpecification>> Use 5 test pieces, and vertically touch the fire of the burner at the lower end of the supported strip test piece for 10 seconds, then let the burner fire leave from the test piece, if the flame is extinguished Immediately after touching the burner fire for 10 seconds, the burner's fire is removed.

After the first and second contact with the fire, there is a flame burning The continuation time, the total of the flame burning duration and the flameless burning duration after the second contact with the fire, the total of the flame burning time of the five test pieces, and the presence or absence of the combustion drop are determined. . in particular:

V-0: no burning drop, the first and the second time together with the fire, the flame burning duration is less than 10 seconds, and the second time has the flame burning duration and no flame. The total burning time is less than 30 seconds. The total of the flame burning time of the test pieces of the other five sheets was within 50 seconds.

V-1: no burning drop, the first and the second time together with the fire, the flame burning duration is less than 30 seconds, and the second time has the flame burning duration and no flame. The total burning time is within 60 seconds. The total of the flame burning time of the test pieces of the other five sheets was less than 250 seconds.

V-2: Same as V-1 except that there is a burning drop.

In addition, because the HB specification and the V specification are different specifications, they cannot be directly compared. However, the V specification is stricter than the HB specification. Even if the HB specification is acceptable, the V specification may not be satisfied. The degree of V-2. Therefore, the good-to-noise sequence of the flame retardant is as shown below, and the more the left side is, the better.

>V-0>V-1>V-2>HB qualified>HB failed. The results are shown in Table 2.

<Production of solar cell back protective sheet 1>

The polyester film (Tetoron S, thickness 188 μm, hereinafter referred to as "transparent substrate A") was subjected to corona treatment on both sides, and a polyester adhesive "Dinareo VA-3020/ was coated on one side by a gravure coater. HD-701" (manufactured by Toyo Ink Holdings Co., Ltd., mixing ratio 100/7, the same applies hereinafter), and then the solvent was dried to provide an interlayer adhesive layer having a coating amount of 10 g/m ² . This interlayer adhesive layer was superposed on the vapor deposition surface of vapor-deposited PET (TECHBARRIER LX, thickness: 12 μm, manufactured by Mitsubishi Plastics Co., Ltd.). Then, the aging treatment was carried out at 50 ° C for 4 days to cure the interlayer adhesive layer, thereby producing a polyester film-vapor deposited PET laminate. Further, the vapor-deposited PET used was a vapor-deposited PET produced by vacuum-depositing vermiculite.

Next, the weather-resistant flame-retardant resin solution 1 described in Table 1A was applied to the polyester film surface of the polyester film-vapor-deposited PET laminate, and then the solvent was dried to provide a weather-resistant flame-retardant resin layer having a film thickness of about 15 μm. Then, the aging treatment was carried out at 40 ° C for 3 days to cure the weather-resistant flame-retardant resin layer, thereby producing a weather-resistant flame-retardant resin layer-polyester film-vapor-deposited PET laminate. Then, the polyester adhesive "Dinareo VA-3020/HD-701" was applied onto the vapor-deposited PET surface by a gravure coater, and the solvent was dried to set a coating amount of 5 g/m ² (film thickness: 5 μm). The layer of the agent was used to fabricate a solar cell back protective sheet 1.

<Production of solar cell back protection sheets 2~14, 101~102, 23, 25~31>

In the same manner as the solar cell back surface protective sheet 1, the solar cell back protective sheets 2 to 14 were produced using the weather resistant flame retardant resin solutions 2 to 14, 101 to 102, 23, and 25 to 31 shown in Tables 1A and 1C. , 101~102, 23, 25~31.

<Production of solar cell back protective sheet 15>

In the same manner as in the case of the solar cell back protective sheet 1, a polyester film-evaporated PET laminate was first produced.

Next, a polyester adhesive "Dinareo VA-3020/HD-701" was applied onto the polyester film of the polyester film-evaporated PET laminate by a gravure coater, and then the solvent was dried to set a coating amount of 10 g/m ^{2 .} Interlayer adhesive layer. Further, the interlayer adhesive layer was superposed on the weather resistant flame-retardant film (film thickness: 30 μm) described in Table 1B. Then, the aging treatment was carried out at 50 ° C for 4 days to cure the weather-resistant flame-retardant resin layer, thereby producing a weather-resistant flame-retardant resin layer-polyester film-vapor-deposited PET laminate. Then, the polyester adhesive "Dinareo VA-3020/HD-701" was applied onto the vapor-deposited PET surface by a gravure coater, and then the solvent was dried to set a coating amount of 5 g/m ² (film thickness: 5 μm). Next, the agent layer was used to fabricate a solar cell back surface protective sheet 15.

<Production of solar cell back protective sheets 16~22, 103~108, 32, 34~39>

In the same manner as the solar cell back surface protective sheet 15, the solar cell back protective sheets 16 to 22 were produced using the weather resistant flame retardant films 16 to 22, 103 to 108, 32, and 34 to 39 shown in Table 1B and Table 1C. , 103~108, 32, 34~39.

<Production of solar cell back protective sheet 40>

The weather-resistant flame-retardant film having a thickness of 5 μm was produced in the same manner as the weather-resistant flame-retardant film 15 and the same composition, and a weather-resistant flame-retardant resin layer was produced in the same manner as the solar cell back surface protective sheet 15 . A solar cell back protective sheet 40 composed of a layer of a polyester film-evaporating PET-adhesive layer.

<Production of solar cell back protective sheet 41>

Except that the weather-resistant flame-retardant resin layer is not provided, the same manufacturing method as that of the solar cell back surface protective sheet 15 is made to have a poly Ester film - a solar cell back surface protective sheet 41 composed of a layer of a vapor-deposited PET-adhesive layer.

[Example 1]

The solar cell back surface protective sheet 1 was used to evaluate the cross-cut adhesion, the flammability, the moist heat resistance, and the weather resistance.

<Cross cutting adhesion measurement>

The cross-cut adhesion is applied to the weather-resistant flame-retardant resin layer of the solar cell back protective sheet 1 by a cutter to give a cross-shaped cut, and then a peeling test is performed with a cellophane tape to visually observe the state of the residual coating film after the cellophane tape is peeled off. The adhesion to the polyester film of the weather resistant flame-retardant resin layer was evaluated.

○: The peripheral portion of the cut was not peeled off.

△: There was a tendency to peel off slightly in the peripheral portion of the cut.

×: Obvious peeling was observed in the peripheral portion of the cut.

<Combustibility Measurement: Radiation Plate (RP) Test>

The flammability is subjected to a flame spread test (radiation plate test) according to ASTM-E162, the flame diffusion coefficient is calculated from the burning rate, and the heat release coefficient is calculated from the combustion temperature, and the product of the two is a flame spread index.

The flame spread test means that the solar cell back protective sheet is ignited in the presence of a radiation plate at 600 ° C, the flame diffusion coefficient is obtained from the burning speed of the solar cell back protective sheet, and the heat release coefficient is obtained from the combustion temperature, and the flame spread is calculated. The method of evaluating the index. The specification value of UL1703 is 100 or less, and it is unacceptable when it exceeds 100.

○: below 50

△: 50 or more ~ less than 100

×: 100 or more ~ less than 150

××: 150 or more

<Heat and heat resistance test>

Moisture and heat resistance was evaluated by using a pressure cooker tester at a temperature of 105 ° C, a relative humidity of 100% RH, and a pressure of 2 atm. The cross-cut adhesion and yellowing and flame spread after leaving for 96 hours, 192 hours, and 288 hours. index. The cross-cut adhesion is evaluated based on the same method and criteria as described above. The yellowness is measured by the method described in JIS-Z8722, using a color difference meter CR-300 (manufactured by Konica Minolta Co., Ltd.), and measured by the side of the weather resistant flame-retardant resin layer of the solar cell back surface protective sheet 1 to L*a*b. * The color of the table indicates the Δb value at the time of evaluation.

○: Δb value is lower than 2

△: Δb value is 2 or more and lower than 4

×: Δb value is 4 or more and less than 10

××: Δb value is 10 or more

<Weatherability test>

The weather resistance was evaluated by the Eye Supa UV tester (manufactured by Iwasaki Electric Co., Ltd.) under the following conditions for cross-cut adhesion, yellowing degree, and film reduction in 10 cycles (i.e., after 120 hours).

(weatherability test conditions)

1) 63 ° C 70% 90mW / cm ² irradiation 4h

2) 70 ° C 90% static 4h

3) Shower for 10 seconds → condensation for 4 hours → shower for 10 seconds

4) The above 1), 2), and 3) were used as one cycle and 10 cycles were repeated (1 cycle, 12 hours. 10 cycles totaled 120 hours).

<film reduction>

a part of the surface of the weather resistant resin layer of each test piece Weatherproof tape protection, the difference between the aforementioned protected portion and the unprotected portion after 10 cycles was measured, and evaluated according to the following criteria.

○: film reduction is less than 1 μm

△: The film is reduced to 1 μm or more and less than 5 μm.

×: The film is reduced to 5 μm or more and less than 10 μm.

××: film reduction is 10 μm or more

[Examples 2 to 14, 101, 102], [Comparative Examples 1, 3 to 9]

In the same manner as in the first embodiment, the solar cell back surface protective sheets 2 to 14, 101, 102, 23, and 25 to 31 were used to evaluate the cross-cut adhesion, the flammability, the moist heat resistance, and the weather resistance. The above results are shown in Table 3.

[Example 15]

The solar cell back surface protective sheet 15 was used, and in the same manner as in Example 1, evaluation of flammability, moist heat resistance, and weather resistance was performed. In the solar cell back surface protective sheet 15 using the weather-resistant flame-retardant film, since the cross-cut adhesion cannot be evaluated, the method described later is used to evaluate the toughness of the weather-resistant resin layer.

<Strong Toughness Measurement>

The solar cell back protective sheet 15 was cut into a rectangular shape of 15 mm in width as a test piece. Each test piece was subjected to a T-stripping test between a weather-resistant flame-retardant resin layer (that is, a weather-resistant flame-retardant film) and a polyester film at a loading speed of 100 mm/min using a tensile tester to evaluate the aforementioned weather resistance. The load when the film is broken.

○: 3N/15mm or more

△: 0.5N/15mm or more ~ less than 3N/15mm

×: less than 0.5N/15mm

××: The weather-resistant flame-retardant resin layer (1) was embrittled, and it was not possible to test and evaluate.

[Examples 16 to 22], [Comparative Examples 10, 12 to 19]

In the same manner as in the fifteenth embodiment, the solar cell back surface protective sheets 16 to 22 and 32, 34 to 41 were used to carry out the toughness, the heat and humidity resistance, the weather resistance of the weather resistant flame retardant resin layer, and the burning of the solar cell back surface protective sheet. Evaluation of sex. The above results are shown in Table 4.

As shown in Tables 3 and 4, Examples 1 to 22 and 101 to 108 (when weather resistant flame retardant resin solutions 1 to 14, 101 to 102 or weather resistant flame retardant resin films 15 to 22 and 103 to 108 are used) Even in the flammability test through the flame spread test, excellent flame retardancy was exhibited. In other words, according to the present embodiment, the weather-resistant flame-retardant resin layer (1) having a thickness of 1/5 or less of the solar cell back surface protective sheet suppresses the combustion (expansion) of the plastic film (2) which is the main constituent member, and solar energy All of the battery back protective sheets have been confirmed to meet the requirements of UL-1703. In addition, it exhibits excellent adhesion after the heat and humidity resistance test or the weather resistance test, and is not easily yellowed even after the heat and humidity resistance test or the weather resistance test, and the thickness of the coating film or the film is not easily obtained even after the weather resistance test. cut back. In other words, the back surface protective sheets for solar cells of Examples 1 to 22 are impeccable back protective sheets for solar cells.

In particular, in Examples 1 to 3, 5 to 8, 15 to 16 and the like using aluminum phosphinate or phosphazene, since the weather-resistant flame-retardant resin layer (1) has high hydrophobicity, it is relatively completely non-added with phosphorus-based flame retardant. Comparative Examples 1, 3, and 10, 12 of the agent (A) (in the case of using the weather-resistant flame-retardant resin solution 23, 25 or the weather-resistant flame-retardant film 32, 34), a significant improvement in moisture heat resistance was observed.

As shown in Table 2, the weather resistant resin films 1 to 18 and 101 to 108 corresponding to Examples 1 to 18 and 101 to 108 exhibited excellent results even in the flame retardancy test specified in UL-94.

On the other hand, in Comparative Examples 1, 3, and 10, and 12, since the phosphorus-based flame retardant was not provided, the flame retardancy was not good, and the specifications of UL-1703 were not satisfied. In particular, the weather-resistant flame-retardant resin film corresponding to Comparative Example 1 and Comparative Example 10 (using the weather-resistant flame-retardant resin solution 23 or the weather-resistant flame-retardant film 32) is shown in Table 2 as a general flame retardancy index. The result of V-0 was exhibited in the test of UL-94, and the result was excellent. However, in the weather resistant flame retardant film, it constitutes a solar cell. The plastic film (2) of the other layers of the back protective sheet, that is, the polyester film of the comparative example, does not have the function of suppressing flammability, and has no fireproof or fire extinguishing effect. As a result, as shown in Tables 3 and 4, when evaluated as the flammability of the solar cell back surface protective sheet by the flame spread test prescribed by ASTM E162, the specification of UL-1703 was not satisfied.

Further, since the phosphorus-based flame retardants of Comparative Examples 4, 6, and 14 (using the weather-resistant flame-retardant resin solution 26, 28 or the weather-resistant flame-retardant film 36) were made of ammonium polyphosphate, Comparative Examples 5, 13, and 15 (used The phosphorus-based flame retardant of the weather-resistant flame-retardant resin solution 27 or the weather-resistant flame-retardant resin film 35, 37) is triphenyl phosphate, and the flammability evaluation of the flame spread test shows the effect of flame retardancy. However, significant deterioration was observed in the damp heat test. That is, it is known that the phosphoric acid of the strong acid generated by the hydrolysis of ammonium polyphosphate or triphenyl phosphate in the wet heat test deteriorates and embrittles the weather-resistant flame-retardant resin layer (1) or the plastic film (2).

Further, in Comparative Examples 7, 8, and 16 (using the weather-resistant flame-retardant resin solution 29, 30 or the weather-resistant flame-retardant film 38), the flame retardant is melamine cyanurate or aluminum hydroxide, so weather resistance and resistance are maintained. There is no big problem with damp heat. However, unlike the case where the phosphorus-based flame retardant forms a carbonized film and exhibits flame retardancy, since the melamine cyanurate and aluminum hydroxide do not form a carbonized film, the flame retarding effect is insufficient. In addition, when the blending amount of the flame retardant is increased in order to improve the flame retardancy, the weather resistant resin (1) is relatively small, and in addition to the difficulty in the production of the weather resistant flame retardant resin layer (1) itself, It is predicted that it has a large influence on weather resistance, heat and humidity resistance and the like.

Further, in Comparative Example 9 (using the weather-resistant flame-retardant resin solution 31), benzotriazole was used as the weather-resistant resin (B), and an acrylic resin having a valence of 38 was used, so that the weather resistance was excellent, but the flame retardancy was used. Excellent phosphinate and excellent physical properties at the beginning, plastic film (2) will occur after damp heat test Since the phosphinate weather-resistant flame-retardant resin layer (1) excellent in moisture-heat resistance is peeled off, the flame retardancy after the damp heat test cannot be maintained.

Further, in the flame retardant of Comparative Example 17 (using the weather-resistant flame-retardant film 39), decabromodiphenyl ether of a halogenated flame retardant was used, so that the flame retardancy was not much problem. However, if it is subjected to a weather resistance test or a damp heat test, there is a significant yellowing, so that the components of the solar cell module are not favorable for the frequent exposure to light or damp heat.

In Comparative Example 18 (Using the weather-resistant flame-retardant film 40), since the film thickness t of the weather-resistant flame-retardant resin layer (1) is too thin compared with the total film thickness of the solar cell back surface protective sheet, there is no flame retardant effect.

In Comparative Example 19 (using the weather-resistant flame-retardant resin film 41), since the weather-resistant flame-retardant resin layer (1) was not provided, the plastic film (2) was exposed on the surface, and the flammability was also inferior except that the weather resistance was remarkably poor.

Further, in Example 9 (using the weather-resistant flame-retardant resin solution 9), since the total phosphorus concentration was low, the flame-retardant test was slightly inferior in flame retardancy, and Examples 10 and 18 (using the weather-resistant flame-retardant resin solution 10 or weather resistance were difficult). In the flammable film 18), since the amount of the phosphorus-based flame retardant (A) is large, the total amount of the weather-resistant resin (B) is relatively small, so that the weather resistance or the moist heat resistance is lowered. Further, in Examples 101 to 104 (using the weather-resistant flame-retardant resin solutions 101 to 104), since the amount of the phosphorus-based flame retardant added was small, the flame-retardant test was slightly inferior in flame retardancy.

Further, in the weather resistant resin (B) of Examples 11 to 14 (using the weather-resistant flame-retardant resin solutions 11 to 14), a urethane-based resin was used, and Examples 19 to 22 (using a weather-resistant flame-retardant resin film 19~) 22) The weather resistant resin (B) is a polyester resin, so that it is slightly inferior in moist heat resistance and weather resistance when a fluorine-based resin is used. However, Examples 11, 12, 19, 20 using phosphinate or phosphazene due to Since the weather-resistant flame-retardant resin layer (1) has high hydrophobicity, it is excellent in moist heat resistance compared to Examples 13, 14, 21, and 22 using phosphoric acid melamine. Further, in Examples 105 to 108 (using the weather-resistant flame-retardant resin film 105 to 108), since a polyester resin having an intrinsic viscosity of 0.67 (dl/g) and a cyclic trimer content of 0.5% by weight was used, A general polyester resin is excellent in weather resistance and moist heat resistance, and is preferably used as a weather resistant flame retardant resin layer.

The application is based on the priority of Japanese Patent Application No. 2011-170505, filed on Aug. 3, 2011, and the Japanese Patent Application No. 2012-096934, filed on Apr. 20, 2012. Into this article.

I‧‧‧Solar cell surface sealing sheet on the light-receiving side of solar cells

II‧‧‧ Sealant layer on the light-receiving side of solar cells

III‧‧‧Solar battery components

IV‧‧‧ Sealant layer on the non-light-receiving side of solar cells

V‧‧‧Solar battery back protection sheet

1‧‧‧ weather resistant flame retardant resin layer

2‧‧‧Plastic film

3‧‧‧ adhesive layer

4‧‧‧Water Vapor Barrier

5‧‧‧Interlayer adhesive layer

Fig. 1 is a schematic cross-sectional view showing a module for a solar cell of the present invention.

Fig. 2A is a schematic cross-sectional view showing an example of a solar cell back surface protective sheet of the present invention.

Fig. 2B is a schematic cross-sectional view showing an example of a solar cell back surface protective sheet of the present invention.

Fig. 2C is a schematic cross-sectional view showing an example of the solar cell back surface protective sheet of the present invention.

Claims (5)

A solar cell back surface protective sheet comprising a weather resistant flame-retardant resin layer (1) having a film thickness t (μm), a plastic film (2), and an adhesive layer (3), wherein One surface of the solar cell back surface protective sheet is composed of the weather resistant flame-retardant resin layer (1), and the other surface of the solar cell back surface protective sheet is composed of the above-mentioned easy-adhesive layer (3), and the weather-resistant flame-retardant resin layer ( 1) a phosphorus-based flame retardant (A) and a weather-resistant resin (B), wherein the phosphorus-based flame retardant (A) is selected from the group consisting of a phosphazene compound, a phosphinic acid compound, and (poly)phosphoric acid melamine In the group, the weather resistant resin (B) is selected from the group consisting of a fluorine resin, a urethane resin, and a polyester resin, and the film thickness t of the weather resistant flame retardant resin layer (1) is the solar battery. The total thickness of the back protective sheet is 2.5 to 20%, and the total phosphorus concentration of the phosphorus-based flame retardant (A) in the weather resistant flame-retardant resin layer (1) is 2.1 to 14.2% by weight. The solar cell back surface protective sheet of the first aspect of the invention, wherein the weather resistant flame retardant resin layer (1) contains 20 to 50% by weight of the phosphorus-based flame retardant (A). The solar cell back surface protective sheet according to claim 1 or 2, wherein the total phosphorus concentration of the phosphorus-based flame retardant (A) in the weather-resistant flame-retardant resin layer (1) is 3 to 10% by weight. The solar cell back surface protective sheet according to claim 1 or 2, wherein the weather resistant resin (B) is a fluorine resin, or has an intrinsic viscosity of 0.6 (dl/g) or more and a cyclic trimer content of 1 weight. An oligomer polyester resin of less than %. A solar cell module comprising a solar cell surface sealing sheet (I) on a light receiving surface side of a solar cell, a sealing material layer (II) on a light receiving surface side of the solar cell, and a solar cell element (III). a sealing agent layer (IV) on the non-light-receiving surface side of the solar cell, and a solar cell according to any one of claims 1 to 4, which is adjacent to the non-light-receiving surface side sealant layer (IV) The solar cell module in which the back surface protective sheet (V) is formed, wherein the weather resistant flame-retardant resin layer (1) constituting the solar cell back surface protective sheet is located farthest from the solar cell surface sealing sheet (I).