KR20140031406A - Solar cell rear surface protective sheet and solar cell module - Google Patents

Abstract

Which is excellent in flame retardancy satisfying the characteristics of the flame propagation test prescribed in UL-1703, excellent in long-term moisture resistance and long-term outdoor weatherability, and is more inexpensive. The solar cell back protection sheet of the present invention comprises a weather resistant flame retardant resin layer 1, a plastic film 2 and a easy adhesive layer 3 having a thickness of t (占 퐉). In the case of a solar cell, The weather resistant flame retardant resin layer (1) and the other side constitute the easy adhesive layer (3). The flame retardant resin composition according to claim 1, wherein the weather-resistant flame retardant resin layer (1) is selected from the group consisting of a phosphorus-based flame retardant (A) selected from the group consisting of a phosphazene compound, a phosphinic acid compound and a (poly) And a weather-resistant resin (B). 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 protective sheet in the case of a solar cell, and the total phosphorus concentration of the phosphorus flame retardant resin (A) 14.2% by weight.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a solar cell module,

The present invention relates to a solar cell back protection sheet comprising a weatherproof flame retardant resin layer, an easy adhesive layer and a plastic film. Further, the present invention relates to a solar cell module using a protective sheet as a back surface of the solar cell.

Recently, as the awareness of environmental problems has increased, there is no environmental pollution, and solar cells are attracting attention as a clean energy source. There are various types of solar cell elements, and typical examples thereof include a crystalline silicon solar cell device, a polycrystalline silicon solar cell device, an amorphous silicon solar cell device, a copper indium selenide solar cell device, and a compound semiconductor solar cell device.

A simple example of the solar cell module is a configuration in which filler glass is sequentially laminated on both sides of a solar cell element. The glass is excellent in transparency, weatherability and abrasion resistance, and is now generally used as a sealing sheet on the light receiving surface side of the sun. However, on the side of the non-light-emitting surface which does not require transparency, a protective sheet (hereinafter also referred to as a "backsheet") for solar cells other than glass in terms of cost, safety and processability has been developed by each company and replaced by glass.

Examples of the back surface protective sheet include a single layer film such as a polyester film, a sheet provided with a vapor-deposited layer of a metal oxide and a non-metallic oxide on a polyester film, and a multilayer film obtained by laminating a film such as polyester film, fluorine film, olefin film, (Patent Documents 1 to 3).

In order to enhance dimensional stability, Patent Document 4 proposes a back surface protective sheet made of a fluororesin sheet having a specific structure of 30 mu m or less in thickness. Patent Document 5 proposes a backsheet in which a gas barrier layer made of silicon nitride and a fluororesin laminated on a base sheet in order to obtain a high vapor barrier property and bend resistance. Another example of using a fluororesin-based resin sheet is disclosed in Patent Document 6, which is obtained by forming an adhesive resin layer containing an azidil group in a film formed of a fluorine-containing resin having a specific structure and a fluorine-free resin. Patent Document 7 proposes a backsheet using an amorphous fluoropolymer in order to realize weather resistance, heat resistance, complementarity, adhesiveness to a layer and an encapsulating material, and scratch resistance.

(Patent Document 8) discloses a backing sheet comprising a plastic film base, an adhesive layer, a water vapor barrier layer and a light-resistant resin layer formed from a resin composition containing a vinyl copolymer (A), a polyisocyanate compound (B), and a polyester A protective sheet has been proposed. Patent Document 9 proposes a laminated sheet in which an outer layer sheet (backsheet or front sheet) and a sealing resin layer are laminated and integrated. The use of a polyphenylene ether-based resin layer as the outer layer sheet is known to be excellent in durability, flame retardancy, dimensional stability, good adhesion to the encapsulating resin layer, and improved handling.

In addition, by providing a coating layer containing a phosphorus-based and inorganic flame retardant agent on a thermoplastic resin film having no flame-retardant property, it is possible to obtain flame retardancy levels equivalent to those of HB and V-2 specified in UL-94 of US UNDERWRITERS LABORATORIES (Patent Literature 10 to 14), and a use as a solar cell has also been proposed.

Patent Document 15 discloses a constitution of an encapsulant provided at a predetermined position between a back-up protective sheet and a power generating element satisfying flame retardancy described in Article 109 (1) of the Enforcement Decree of the Japanese Building Standard Act. Specifically, an encapsulating material formed using a sealing material composition containing a polyolefin resin and flame-retardant particles ranging from 0.1 wt% to 10 wt% is disclosed. In Patent Document 16, a phosphazene compound having a predetermined structure in a solar cell encapsulating film containing an ethylene-vinyl acetate copolymer and an organic peroxide with a structure satisfying the UL-94 HB standard is mixed with 100 parts by mass of an ethylene-vinyl acetate copolymer 0.1 to 30 parts by mass based on 100 parts by mass of the polymer. In Patent Document 17, an insulating layer, an insulating intermediate layer, a solar cell, and an organic resin intermediate layer as a covering material are stacked in this order, and an insulating intermediate layer, a solar cell, an organic insulating layer A solar cell module in which a fluorine plastic layer covering the resin intermediate layer is further laminated is shown. An example in which a coating material is composed of a material containing a solvent-soluble fluororesin in a flammable organic resin as compared with a fluororesin, and a phosphazene compound is blended is disclosed.

In addition, a coating agent containing an inorganic pigment and a flame retardant in a fluorine resin as a coating agent for imparting flame retardancy to a protective sheet in the case of a solar cell has been proposed after the prior art which is the basis of priority. (Patent Document 18).

Japanese Patent Application Laid-Open No. 2004-200322 Japanese Patent Application Laid-Open No. 2004-223925 Japanese Patent Application Laid-Open No. 2001-119051 Japanese Patent Application Laid-Open No. 2003-347570 Japanese Patent Application Laid-Open No. 2010-219196 Japanese Patent Application Laid-Open No. 2004-352966 Japanese Patent Application Laid-Open No. 2010-519742 Japanese Patent Application Laid-Open No. 2008-098592 Japanese Patent Laid-Open Publication No. 2011-146671 Japanese Patent Application Laid-Open No. 2009-179037 Japanese Patent Application Laid-Open No. 2010-89334 Japanese Patent Application Laid-Open No. 2010-120321 Japanese Patent Application Laid-Open No. 2010-149447 Japanese Patent Application Laid-Open No. 2010-234741 Japanese Patent Laid-Open Publication No. 2011-134986 Japanese Patent Laid-Open Publication No. 2011-114118 Japanese Patent Application Laid-Open No. 06-196742 Japanese Patent Application Laid-Open No. 2011-162598

Various proposals have been made so far to achieve high performance of solar cell modules. There have been proposed a method using a fluorine resin for members such as a sealing material or a back protection sheet in a method of realizing the flame retardancy and a film containing a flame retardant in a thermoplastic resin film.

The flame retardancy of general polymeric materials is evaluated by the HB test or the V (VTM) test specified in UL-94 described above, depending on the time from ignition to decontamination. Also in the above-mentioned conventional examples, a laminated film satisfying the flame retardancy level equivalent to HB and V-2 according to the UL-94 standard has been proposed. However, in the case of solar cell modules and solar cells, the standards for the combustibility of the protective sheet are specified in IEC61730-1, IEC61730-2 and UL-1703, which are standards for solar cells. Among them, (Radiant panel test, ASTM E162) is required in the market. The flame propagation test is based on the evaluation of the flame transmission rate, that is, the flame spreading coefficient, obtained from the combustion temperature (≒ thermal emission coefficient), (ii) the combustion rate (≒ flame diffusion coefficient) Which is different from the HB test and the V (VTM) test, which are evaluated according to the time from the start of the test.

In order to enhance the flame retardancy, a method of using glass as a back side protective member is effective, but as described above, materials other than glass are being replaced in terms of cost, safety, and processability. Therefore, it is an important task to provide a backsheet satisfying UL-1703 in a protective sheet in the case of a solar cell. In addition, the solar cell module is required to have excellent long-term moisture resistance and long-term outdoor weatherability that can withstand harsh outdoor conditions in addition to flame retardancy. In addition, it is important to provide solar cells at low cost in order to accelerate the diffusion of solar cell modules.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a flame retardant material which satisfies the characteristics of the flame propagation test specified in UL-1703 and is excellent in long-term moisture resistance and long-term outdoor weatherability, A solar cell module comprising a solar cell backing sheet and a solar cell backing sheet.

DISCLOSURE OF THE INVENTION In order to achieve the above object, the inventors of the present invention have conducted intensive studies and, as a result, have found that the problems of the present invention can be solved in the following embodiments, and have completed the present invention. That is, the solar cell backing sheet of the present invention is a solar cell backing sheet comprising a weather-resistant flame retardant resin layer 1, a plastic film 2 and an easy adhesive layer 3 each having a thickness t (占 퐉) The weather-resistant flame retardant resin layer (1) constitutes one side of the protective sheet on the back side of the battery. The easy adhesive layer (3) constitutes the other surface of the protective sheet on the back surface of the solar cell. The weather-resistant flame retardant resin layer (1) comprises a phosphorus flame retardant (A) selected from the group consisting of a phosphazene compound, a phosphinic acid compound and a (poly) phosphoric acid melamine and a fluororesin, a urethane resin and a polyester resin Wherein 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 protective sheet in a solar cell, and the weather resistant resin layer (1) Of phosphorus-based flame retardant (A) is 2.1 to 14.2% by weight.

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

The solar cell module of the present invention comprises a solar cell surface sealing sheet (I) 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, a solar cell element A solar cell module comprising an encapsulant layer (IV) on a non-light-receiving surface side of a solar cell and the solar cell backsheet (V) in contact with the non-light-receiving surface side encapsulant layer (IV) The weather-resistant flame retardant resin layer 1 constituting the back surface protective sheet is the farthest from the solar cell surface seal sheet I.

According to the present invention, there is provided a solar cell back protection sheet which has flame retardancy satisfying the characteristics of the flame propagation test specified in UL-1703, is excellent in long-term moisture resistance and long-term outdoor weatherability, It is possible to provide a solar cell module using a protective sheet.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a diagram schematically showing a cross section of a solar cell module of the present invention. FIG.
2A is a schematic cross-sectional view showing an example of a solar cell backing sheet of the present invention.
FIG. 2B is a schematic cross-sectional view showing an example of a protective sheet for a back surface solar cell according to the present invention. FIG.
2C is a schematic cross-sectional view showing an example of a protective sheet for a solar cell according to the present invention.

Hereinafter, the present invention will be described in detail. Needless to say, other embodiments are also included in the scope of the present invention as long as the spirit of the present invention is satisfied. Also, in this specification, the expression " any number A to arbitrary number B " means a range that is larger than the number A and the number A, and smaller than the number B and the number B.

In the case of a solar cell, the protective sheet is required to meet the flame propagation test specified in UL-1703, as described above. In addition, the lifetime of the solar cell modules is required to be 15 ~ 25 years long, and long-term weatherability and long-term moisture resistance are required for the protective sheet. In addition, it is also required that the protective sheet satisfies the withstand voltage property when the solar cell is used.

From the viewpoint of ensuring the withstand voltage property, the thickness of the protective sheet in the case of a solar cell may vary depending on the thickness of the constituent material or the sealing material, but is preferably 250 m or more. In addition, from the viewpoints of the flexibility, productivity, and cost of the protective sheet, it is preferable that the thickness of the solar cell is 400 탆 or less. It is also important to provide a protective sheet at low cost in the case of solar cells. Therefore, it is ideal to prevent the expansion of the whole of the protective sheet and to realize flame retardancy and anti-flammability in the case of a solar cell while the ratio of the thickness of the plastic film 2, which is a main component of the protective sheet, is large. From this point of view, when the thickness of the protective sheet is set in the range of 250 to 400 mu m, it is preferable that the thickness of the plastic film 2 is in the range of 125 to 250 mu m. The material of the plastic film 2 is not particularly limited, but a thermoplastic resin such as a polyester film or an olefin film is preferable from the viewpoint of affordability.

As a result of intensive investigations by the present inventors, it has been found that, by satisfying all of the following constitutions (i) to (v), it surprisingly has flame retardancy satisfying the characteristics of the flame propagation test prescribed in UL-1703, It has been found that a protective sheet can be provided as long as it is excellent in long-term outdoor weatherability, excellent in withstand voltage, and is more inexpensive.

(i) In the solar cell backing sheet of the present invention, it is assumed that the protective sheet is provided with the weather-resistant flame retardant resin layer 1, the plastic film 2 and the easy adhesive layer 3 having a thickness t (占 퐉).

(ii) In the case of a solar cell, the outermost layer of the protective sheet disposed on the solar cell side is an easy adhesive layer 3, and the other outermost layer is a weatherproof flame retardant resin layer 1.

(i) The weather-resistant flame-retardant resin layer (1) is selected from the group consisting of a phosphazene compound, a phosphinic acid compound and a (poly) phosphoric acid melamine, and a flame retardant (A) selected from the group consisting of a fluorine resin, a urethane resin and a polyester resin (B) selected from the group consisting of polyolefin resins and polyolefin resins.

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

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

Hereinafter, (i) to (v) will be described in detail.

By satisfying (i) to (iii) in the backing sheet of the solar cell of the present invention, it is possible to provide the solar cell module at low cost while providing weathering resistance and flame retardancy, and also maintain good adhesion in the solar cell module. As a method of imparting flame retardancy, a method of adding a flame retardant to the entire protective sheet in the case of a solar cell, a method of separately providing a flame retardant layer and a weather-resistant layer, or a method of adding a flame retardant to the intermediate layer may be considered. However, the present invention adopts a mode in which a weather resistant resin is disposed on the outermost layer which is farthest from the solar cell element, and a flame retardant is added thereto. The weather-resistant flame-retardant resin layer 1 protects the inside of the protective sheet and the solar cell module from external factors such as ultraviolet rays and physical impact when the solar cell is used. Therefore, the adhesion with the inner layer can be enhanced while suppressing the output reduction of the solar cell element. As a result, the effect of the flame retardancy can be made more reliable.

Examples of flame retardants generally used include phosphorus flame retardants, nitrogen flame retardants, silicon flame retardants, and inorganic flame retardants.

Examples of the phosphorus flame retardant include phosphoric acid compounds such as melamine phosphate, melamine polyphosphate, guanidine phosphate, guanidine polyphosphate, ammonium phosphate, ammonium polyphosphate, ammonium phosphate amide, ammonium polyamide, phosphoric acid carbamate, polyphosphoric acid carbamate, Organic phosphoric acid ester compounds, phosphazene compounds, phosphonic acid compounds, phosphinic acid compounds, phosphine oxide compounds, phosphorane compounds, and phosphorus amide compounds.

Examples of the nitrogen-based flame retardant include triazine-based compounds such as melamine, melam, melem, melon and melamine cyanurate, cyanuric acid compounds, isocyanuric acid compounds, triazole-based compounds, tetrazole compounds, diazo compounds and urea .

Silicon-based flame retardants include silicone compounds and silane compounds.

Examples of the halogen-based flame retardant include low-molecular halogen-containing compounds such as halogenated bisphenol A, halogenated epoxy compounds and halogenated phenoxy compounds, halogenated oligomers and polymers.

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

As shown in the above example, there are many types of flame retardants. As a result of repeated studies by the present inventors in a large number of flame retardants, it has been found that (iii) a phosphorus flame retardant (A), either phosphazene compound, phosphinic acid compound or melamine (poly) phosphate is useful.

First, the reason why the flame retardant other than the above (iii) is inappropriate will be explained. The nitrogen-based flame retardant and the inorganic flame retardant need to be added in a large amount in order to exhibit the flame retardant effect. As a result, there arises a problem that the weather resistance and heat and humidity resistance of the weather resistant flame retardant resin layer 1 are significantly lowered. In addition, the halogen-based flame retardant agent is visually avoided by weathering resistance test and weather resistance test because the weather-resistant flame retardant resin layer is largely yellowed. Further, in the weatherability test, there is a problem that the flame retardant promotes deterioration of the weather-resistant resin (B).

In addition, the phosphorus flame retardant is preferable in that it can exhibit flame retardancy with a relatively small addition amount. For example, the (poly) phosphate and the (poly) phosphorus acid carbamate used in a flexible printed board or the like But gradually decomposes to produce phosphoric acid, which is a strong acid. The resulting phosphoric acid serves as a catalyst for hydrolysis of the weather-resistant resin (B), and greatly degrades the weather-resistant flame-retardant resin layer (1). Therefore, a flame retardant that generates an acid by hydrolysis in the anti-wet heat test is not preferable even in the phosphorus flame retardant.

The phosphorus-based flame retardant (A) of the present invention can effectively exhibit flame retardancy with a small addition amount to such an extent that it does not affect weather resistance and heat and humidity resistance. It is also excellent in that no acid is generated by hydrolysis. In addition, the phosphorylated flame retardant (A) itself has high moisture resistance and hardly undergoes hydrolysis at the time of wet heat degradation. It is possible to effectively prevent the adhesion of the weather resistant flame retardant resin layer 1 to the plastic film 2 from being deteriorated. That is, by using the phosphorus-based flame retardant (A) of the present invention, it is possible to improve the moisture resistance and heat resistance of the weather-resistant resin (B) Emission factor), and (ii) a reduction in the burning rate (= the flame diffusion coefficient).

Since the phosphazene compound and the phosphinic acid compound among the phosphorus flame retardant agent (A) are filler-like compounds having a very high hydrophobicity, the hydrophobicity of the weather-resistant flame retardant resin layer (1) can be more effectively increased by using such a compound. Namely, it is possible to exhibit higher resistance to moisture and humidity than in the case of a weather-resistant resin (B) selected from the group consisting of a fluorine resin, a urethane resin and a polyester resin. Therefore, the solar cell is very suitable as a flame retardant for a protective sheet.

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

(1)

(2)

In the formula (1) or (2), R ¹ and R ² are each a hydrogen atom or a monovalent organic group containing no halogen, and the monovalent organic group of R ¹ and R ² is a phenyl group, an alkyl group, An aryl group, and the phenyl group and the like may each further have a substituent containing no halogen. The substituent may be selected from the group consisting of a hydroxyl group, an amino group, a cyano group and a nitro group. n is an integer of 3 to 10;

The cyclophosphazene wherein R ¹ or R ² is a phenyl group or an alkyl group is preferable, and cyclophosphazene is more preferably tricyclophosphazene. Specifically, hexaalkoxytricyclophosphazene and hexaphenoxytricyclophosphazene can be mentioned, and hexaphenoxytricyclophosphazene is preferable.

As hexaalkoxytricyclophosphazene, hexamethoxytricyclophosphazene, hexaethoxytricyclophosphazene, hexapropoxytricyclophosphazene and the like can be given.

As hexaphenoxytricyclophosphazene, hexaphenoxytricyclophosphazene having substituent such as other hydroxyl group or cyano group in addition to unsubstituted hexaphenoxy tricyclophosphazene is available.

As the phosphinic acid compound, the phosphinic acid salt exemplified in the following chemical formula (3) can be mentioned.

(3)

In the chemical formula (3), R ¹ and R ² are the same or different and each represents an alkyl group or an aryl group having 1 to 6 carbon atoms in a linear or branched form and M represents at least one element selected from the group consisting of Mg, Ca, Al, Sb, Sn, Ge, Ti At least one metal selected from the group consisting of Zn, Fe, Zr, Ce, Bi, Sr, Mn, Li, Na and K; More preferred compounds include phosphinic acid salts wherein M is Mg, Ca or Al, and aluminum phosphinate acid salts in which M is Al are particularly preferred. Specifically, R < ¹ > and R < ² > are preferably an alkyl group and an aluminum salt of tris dialkyl phosphinic acid with n = 3.

The (poly) phosphoric acid melamine may be a compound represented by the following chemical formula (4) in which the phosphoric acid and the melamine exhibit a salt state. In the following chemical formula (4), n is preferably 1 to 10, and when n is 2 or more, it is referred to as " melamine polyphosphate ".

Formula (4)

The above phosphorylated flame retardant (A) may be used singly or in combination of plural compounds in each compound group or may be arbitrarily combined in various compound groups.

The weather-resistant resin (B) prevents the deterioration of the phosphorus-based flame retardant (A) due to ultraviolet rays, physical impact, and the like, and plays a role as a binder because the phosphorus flame retardant (A) uniformly exists in the weather-resistant flame retardant resin layer (1) without aggregation.

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 resin include a polyurethane resin, a polyether polyurethane resin, a polycarbonate polyurethane resin and urethane resins other than the polyurethane resin. Urethane urea resins having urea bonds in the above various urethane resins can also be regarded as urethane resins. In order to improve the weatherability, an ultraviolet absorber, a light stabilizer and an antioxidant may be combined with the weather-resistant resin (B), and an ultraviolet absorber, a light stabilizer and an antioxidant may be added to the weather-resistant resin (B).

The fluororesin preferably used as the weather-resistant resin (B) contains 50 mol% or more and 100 mol% or less of a fluorine-bonded monomer (hereinafter also referred to as a fluorine-containing monomer) component at a site directly bonded to the main chain carbon. However, a block copolymer having a block containing no fluorine-containing monomer component is not preferable even if the fluorine-containing monomer is copolymerized in an amount of 50 mol% or more as a whole. In other words, the fluorine-containing monomer may be randomly copolymerized with the fluorine-containing monomer copolymer, the fluorine-containing monomer may be copolymerized with the fluorine-containing monomer, or the fluorine-containing monomer copolymer may be copolymerized with the fluorine- The copolymer of the monomers corresponds to the fluororesin of the present invention.

Preferred examples of the fluorine-containing monomer is _{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.

Examples of the fluororesin suitable for the weatherable resin (B) include polytetrafluoroethylene (PTFE), polychlorotrifluoroethylene (PCTFE), polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), perfluoroalkoxy fluorine (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), ethylene-tetrafluoroethylene copolymer (ETFE), and ethylene-chlorotrifluoroethylene copolymer (ECTFE).

The fluorine-based resin is excellent in weather resistance and chemical resistance, and is suitable as the weather-resistant resin (B). Since the fluorine-based resin composed of the fluorine-containing monomer has no urethane bond or ester bond which may be hydrolyzed in the main chain, a trace amount of acid generated in the phosphorus flame retardant (A) becomes a catalyst and causes hydrolysis Can not. Therefore, it is preferable to a urethane-based resin or a polyester-based resin. When ammonium phosphate is used for the urethane resin and the polyester resin, for example, ammonium phosphate is decomposed in an anti-heat test to generate phosphoric acid, which is a strong acid. Since phosphoric acid decomposes the urethane resin and the polyester resin, the flame retardant such as ammonium phosphate is not applied to the solar cell rear protective sheet.

The polyester resin suitable for the weather-resistant resin (B) is obtained by reacting a carboxylic acid component having a carboxylic acid group with a hydroxyl group 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, azelaic acid, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, 1,4-cyclohexanedicarboxylic acid, anhydrous trimellitic acid, methylcyclohexanetricarboxylic acid anhydride, anhydrous pyromellitic acid, epsilon -caprolactone, and fatty acids can be exemplified.

Examples of the hydroxyl group component include ethylene glycol, propylene glycol, 1,3-butylene glycol, 1,6-hexanediol, diethylene glycol, dipropylene glycol, neopentyl glycol, triethylene glycol, 4-cyclohexane dimethanol and the like, and polyfunctional alcohols such as glycerin, trimethylol ethane, trimethylol propane, trishydroxymethylaminomethane, pentaerythritol, dipentaerythritol and the like.

The weather-resistant resin (B) can be obtained by polymerizing a carboxylic acid component and a hydroxyl group component to form a predetermined polyester resin according to a conventional method. The polyester-based resin is preferably a low-oligomer polyester-based resin from the viewpoint of satisfying the combustion test (UL-1703, UL-94), weather resistance, and heat and humidity resistance.

The low 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 0.6 to 1.2 (dl / g). The intrinsic viscosity of the polyester-based resin is determined by extrapolating? Sp / c obtained by dividing the viscosity (? Sp = (? /? 0) -1) of the solvent resin by the concentration c (g / mL) C is the viscosity of the solvent at c (g / mL), and sp is the viscosity of the resin solution and viscosity of the solvent.

The smaller the cyclic trimer content of the polyester-based resin is, the more preferable it is 0.5 wt% or less. The cyclic trimer content of the polyester resin is determined by dissolving 100 mg of the polyester resin in 2 mL of orthochlorophenol and measuring the weight percentage by liquid chromatography.

The urethane-based resin suitable for the weather-resistant resin (B) is obtained by reacting a hydroxyl group component other than a polyester resin having a hydroxyl group with an isocyanate compound.

Examples of the hydroxyl group component include polyethylene glycol, polypropylene glycol, polyether polyol to which ethylene oxide or propylene oxide is added, polymer polyol such as acryl polyol and polybutadiene polyol, and the like.

The isocyanate compound may be the same as the polyisocyanate compound (C) to be described later. Trimethylene diisocyanate (TDI), hexamethylene diisocyanate (HDI), methylenebis (4,1-phenylene) = diisocyanate (MDI), 3-isocyanatomethyl-3,5,5-trimethylcyclohexylisocyanate ), Isocyanates such as xylene diisocyanate (XDI), trimethylolpropane adducts of such diisocyanates, trimerized isocyanurate derivatives of such diisocyanates, biuret conjugates of such diisocyanates, and polymeric isocyanates have.

In order to impart higher toughness, weatherability, and heat and humidity resistance by the weather-resistant resin (B), an adhesive capable of reacting in the side chain of the weather-resistant resin (B) may be introduced and crosslinked with a general crosslinking agent to obtain a higher crosslinking density. Examples of the crosslinking agent include polyisocyanate compounds, polyglycidyl compounds, and polyaziridyl compounds.

As the curing agent having a functional group capable of reacting with a polyester-based or urethane-based resin having a hydroxyl group and a isocyanate hydroxyl group in view of durability and coating stability, an isocyanate compound is preferable. Further, a polyisocyanate compound is preferable in terms of improvement in durability.

The polyisocyanate compound is used to form a weather resistant resin layer having a stretchability, flexibility, molding processability, scratch resistance, long-term weatherability, long-term moisture resistance and chemical resistance while bridging the weather-resistant resin (B) with each other. It is preferable to use only alicyclic or aliphatic compounds in order to prevent the obtainable weather-resistant resin layer from discoloring from yellow to brown with time.

Examples of the alicyclic polyisocyanate compound include isophorone diisocyanate, hydrogenated triisocyanate, hydrogenated 4,4'-diphenylmethane diisocyanate, and the like.

The aliphatic polyisocyanate compound includes, for example, trimethylhexamethylene diisocyanate, hexamethylene diisocyanate, and lidine diisocyanate.

Examples of the aromatic polyisocyanate compound include diphenylmethane diisocyanate, tolyl diisocyanate, naphthylene-1,5-diisocyanate, o-xylene diisocyanate, m-xylene diisocyanate, p- Phenylmethane triisocyanate, and polymethylene polyphenyl isocyanate.

As the polyisocyanate compound, both end isocyanate adducts, biuret modified products and isocyanurate modified products which are reaction products with the above compounds and glycols or amines may be used.

Particularly, when the polyisocyanate compound contains an isocyanurate-modified product, particularly an isocyanurate ring-containing triisocyanate, it is preferable because it is possible to obtain a weather-resistant resin layer having stronger stretchability. Specific examples of the isocyanurate ring-containing triisocyanate include isocyanate-modified isophorone diisocyanate (e.g., Desmodur Z4470 of Sumitomo Bayer Urethane Co., Ltd.), isocyanate-modified hexamethylene diisocyanate (e.g., Sumitomo Bayer Urethane N3300), and isocyanate-modified tolyl isocyanate (e.g., Sumidol FL-2 FL-3, FL-4 and HL BA from Sumitomo Bayer Urethane Co.). The isocyanurate ring may be reacted with a polyester (c) having two or more functional groups that can be further reacted to increase the isocyanate group in one molecule. The resulting urethane bond may also be reacted with one equivalent of an isocyanate group, To increase the isocyanate group in one molecule. A polyester resin well-known as polyester (c) having two or more functional groups capable of reacting with an isocyanate group can be used.

The isocyanate group of the polyisocyanate compound is preferably selected from the group consisting of methanol, ethanol, n-pentanol, ethylene chlorohydrin, isopropyl alcohol, phenol, p-nitrophenol, m-cresol, acetylacetone, a block-modified product obtained by reacting with a block agent such as? -caprolactam and blocking the product may be used.

It is also possible to use a polyisocyanate compound-terminated isocyanate prepolymer obtained by reacting a polyester (d) having two or more functional groups capable of reacting with an isocyanate group and an isocyanate compound (e) having isocyanate groups at both terminals. When the polyisocyanate compound contains the above-mentioned both-end isocyanate prepolymer, stretchability can be obtained in a small amount and the toughness of the coating film is not impaired. The polyisocyanate compound may be used alone or in combination of two or more.

As the polyester (d) having two or more functional groups capable of reacting with the isocyanate group, well-known polyester resins can be used. Examples of the isocyanate compound (e) having an isocyanate group at both terminals include tolyl isocyanate, naphthylene-1,5-diisocyanate, o-toluylene diisocyanate, diphenylmethane diisocyanate, trimethylhexamethylene diisocyanate, 4,4'-diphenylmethane diisocyanate, hexamethylene diisocyanate, m-xylene diisocyanate, p-xylene diisocyanate, lysine diisocyanate, hydrogenated 4,4'-diphenylmethane diisocyanate, hydrogen Addition triisocyanate and the like.

With respect to the weather-resistant resin (B), the polyisocyanate compound is preferably 0.1 to 5 times the number of isocyanate groups of the polyisocyanate compound with respect to the total number of functional groups (functional groups capable of reacting with isocyanate groups) of the weather-resistant resin (B) , And further preferably 1 to 3 times. When the amount is less than 0.1 times, crosslinking density is too low, and solvent resistance, scratch resistance and weather resistance are not sufficient. If it is more than 5 times, isocyanate remains and reacts with moisture in the air to change physical properties depending on the season.

Examples of the curing agent include oxazoline compounds other than the above polyisocyanate compounds such as 2,5-dimethyl-2-oxazoline, 2,2- (1,4-butylene) -bis (2-oxazoline) A zwitteride compound such as isophthalic acid dihydrazide, sebacic acid dihydrazide, adipic acid dihydrazide.

The content of aromatic rings in the weather-resistant resin (B) is preferably at most 50% by weight and preferably at most 10% by weight, and it is preferable that aromatic rings are not contained as much as possible. When the content of the aromatic ring in the weather-resistant resin (B) selected from the group consisting of a fluorine resin, a urethane resin and a polyester resin exceeds 50% by weight, the ultraviolet light is absorbed and the yellowing and film deterioration of the weather- And the weatherability tends to deteriorate.

In order to improve the slidability and barrier properties of the surface of the weather-resistant flame retardant resin layer 1, inorganic fine particles and organic fine particles may be added.

Specific examples of the inorganic fine particles include inorganic particles containing silica, glass fiber, glass powder, glass bead, clay, walassite, iron oxide, antimony oxide, lithopone, pumice powder, aluminum sulfate, zirconium silicate, dolomite, . In addition, the inorganic fine particles may contain impurities to such an extent that their properties are not impaired. In addition, the shape of the particles may be any shape such as powder, granule, granule, sieve, flat plate, or fiber.

Specific examples of the organic fine particles include polymers such as polyolefin wax, polymethylmethacrylate resin, polystyrene resin, nylon resin, melamine resin, guanamine resin, phenol resin, urea resin, silicone resin, methacrylate resin, Particles, cellulose powder, nitrocellulose powder, wood powder, paper powder, rice hull powder, starch and the like. The organic particles can be obtained by a polymerization method such as an emulsion polymerization method, a suspension polymerization method, a dispersion polymerization method, a soap pre-polymerization method, a seed polymerization method and a micro suspension polymerization method. In addition, the organic particles may contain impurities to the extent that their properties are not impaired. The shape of the particles may be any shape such as powder, particle, granule, flat plate, or fiber.

The weather-resistant flame-retardant resin layer 1 may contain various thermoplastic resins other than the weather-resistant resin (B) within a range not to hinder the effect of the present invention in order to increase the strength of the obtainable weather-resistant flame retardant resin layer. Examples of the thermoplastic resin include polyolefins such as polypropylene, polyethylene, ethylene-vinyl acetate copolymer, polyisobutylene, polybutadiene, polystyrene, polycarbonate, polymethylpentene, ionomer, acrylonitrile-butadiene- , Polyvinyl alcohol, polyamide resin, polyacetal, and epoxy resin.

The addition amount of the thermoplastic resin is preferably 50 parts by weight or less, more preferably 30 parts by weight or less, based on 100 parts by weight of the total amount of the weather-resistant resin (B) selected from the group consisting of a fluorine resin, a urethane resin, and a polyester resin Do. If it exceeds 50 parts by weight, compatibility with other components may be deteriorated.

A pigment may be added to the weather-resistant flame retardant resin layer 1 for coloring. Conventionally known pigments can be used, and inorganic pigments such as carbon black, titanium oxide, zinc oxide, lead oxide, zinc sulfide, lithobon, and various organic pigments can be used.

The phosphorus flame retarding agent (A), the particles and the pigment are preferably mixed with a weather-resistant resin (B) or the like after preparing a paste in which a dispersion resin and a dispersant are mixed as required. As the dispersing resin, it is preferable to use the weather-resistant resin (B) itself, but there is no particular limitation, and a polar group having excellent pigment dispersibility such as acrylic resin having hydroxyl group, carboxyl group, thiol group, amino group, amide group, , A polyurethane resin, a polyurea resin, a polyester resin and the like can be used. Examples of the dispersing agent include pigment derivatives, anionic surfactants, amphoteric surfactants, nonionic surfactants, titanium coupling agents and silane coupling agents. Also. The surface of the pigment may be modified by a metal chelate, a resin coating or the like.

The weatherable 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 protective sheet in a solar cell. For example, in the case of a solar cell having a film thickness of 300 mu m, the film thickness t of the weather-resistant flame retardant resin layer 1 in the case of a protective sheet is set in a range of 7.5 to 60 mu m. The total phosphorus concentration derived from the phosphorus flame retardant (A) in the weather-resistant flame retardant resin layer (1) is set to 2.1 to 14.2 wt%. The thickness t of the weather-resistant flame-retardant resin layer 1 is set within the above-mentioned range, and the total phosphorus concentration is set in a specific range, thereby providing a solar cell backing sheet excellent in flame retardancy and economical efficiency.

The film thickness t of the weather-resistant flame-retardant resin layer 1 is set to 2.5% or more of the total film thickness of the protective sheet in the case of a solar cell, and the combustion of the plastic film 2, which is a main component of the protective sheet, The flame propagation test of UL-1703 can be satisfied. On the other hand, if the thickness t of the weather-resistant flame-retardant resin layer 1 is 20% or more of the total thickness of the protective sheet in a solar cell, it becomes difficult to form a uniform layer or a cost disadvantage increases.

Further, by setting the total phosphorus concentration of the weather-resistant flame retardant resin layer (1) derived from the phosphorus flame retardant (A) to not less than 2.1%, not only the flame retardancy of the coating film itself is satisfactorily maintained but also a sufficient carbonization film is formed, It can be suppressed effectively. As a result, the standard value of the flame propagation test can be satisfied. Also, by setting the total phosphorus concentration to 14.2% or less, it is possible to maintain good weatherability and heat and humidity resistance. A more preferable range of the total phosphorus concentration derived from the phosphorus flame retardant (A) in the weather-resistant flame retardant resin layer (1) is 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 even more preferably 20% by weight or more. 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, and more preferably 50% by weight or less. The amount of the phosphorus flame retardant (A) is included in the range of 10 wt% or more and 60 wt% or less, thereby satisfying the flame retardancy, weatherability, and moisture resistance in a balanced manner. In particular, when it is 20 wt% or more, the flame retardancy can be effectively increased. And the amount of the weather-resistant resin (B) selected from the group consisting of a fluorine resin, a urethane resin, and a polyester resin is suitably maintained, and the weather resistance and moisture resistance can be kept better.

The phosphorus flame retardant (A) comprising a phosphazene compound, a phosphinic acid compound and (poly) phosphoric acid phosphate used in the present invention does not undergo most hydrolysis in the moisture resistance test. However, even in an extremely small amount of acid caused by slight hydrolysis, the acid serves as a catalyst for a very long period of time, and the weather-resistant resin (B) selected from the group consisting of a fluorine resin, a urethane resin and a polyester resin And the deterioration of the weather-resistant flame-retardant combustion resin layer 1 may be compulsorily promoted. Therefore, it is preferable that the weather-resistant resin (B) does not contain a hydrolyzable part in the main chain of the resin.

Next, the plastic film 2 used in the present invention will be described. Examples of the plastic film (2) used in the present invention include polyester resin films such as polyethylene terephthalate, polybutylene terephthalate and polynaphthalene terephthalate, and olefin films such as polyethylene, polypropylene and polycyclopentadiene , Polyvinyl fluoride, a polyvinylidene fluoride film, a polytetrafluoroethylene film, an ethylene-tetrafluoroethylene copolymer film and other fluorine-based films, an acrylic film and a triacetylcellulose film. From the viewpoints of film stiffness and cost, the polyester-based resin film is preferable, and it is preferable that the film is a polyethylene terephthalate film. The plastic film 2 may be a single layer or a multilayer structure of two or more layers.

The plastic film (2) may be colorless or may contain a coloring component such as pigment or dye. The method of containing a coloring component includes, for example, a method in which a coloring component is previously mixed at the time of film formation, a method of printing a coloring component on a colorless transparent film base, and the like. Further, a colored film and a colorless transparent film may be adhered and used.

Next, the easy adhesive layer 3 used in the present invention will be described. The easy adhesive layer (3) of the present invention is a layer for improving adhesion between the plastic film (2) and the non-light-receiving surface side sealing material (IV), and is a resin layer formed on the outermost surface of one side of the protective sheet. When the solar cell module is formed, the non-light-receiving surface side sealing material (IV) and the solar cell backing sheet (V) of the present invention are adhered to the easy adhesive layer (3) The seat is mounted.

The easy adhesive layer 3 used in the present invention can be formed of a general adhesive containing various resins. Preferable examples thereof include polyester resins, urethane resins, and acrylic resins. The resins may be used alone or in combination of two or more. Further, a composite resin of these resins may also be used.

A preferable polyester resin as the easy adhesive layer 3 is a polyester resin obtained by reacting an isocyanate compound with a polyester resin having a hydroxyl group in addition to a polyester resin in which a carboxylic acid component and a hydroxyl group component are reacted (esterification reaction and transesterification reaction) A polyester polyurethane resin which is allowed to react with a diamine component, and the like.

Examples of the carboxylic acid component constituting the polyester resin of the easy adhesive layer (3) include benzoic acid, p-tert-butylbenzoic acid, phthalic anhydride, isophthalic acid, terephthalic acid, succinic anhydride, adipic acid, azelaic acid, Phthalic acid, hexahydrophthalic anhydride, maleic anhydride, fumaric acid, itaconic acid, tetrachlorophthalic anhydride, 1,4-cyclohexanedicarboxylic acid, anhydrous trimellitic acid, methylcyclohexanetricarboxylic acid anhydride, pyromellitic anhydride ,? -caprolactone, fatty acids can be exemplified.

Examples of the hydroxyl group constituting the polyester resin of the easy adhesive layer 3 include ethylene glycol, propylene glycol, 1,3-butylene glycol, 1,6-hexanediol, diethylene glycol, dipropylene glycol, neopentyl glycol , Triethylene glycol, 3-methylpentanediol, 1,4-cyclohexanedimethanol, and the like, glycerin, trimethylolethane, trimethylolpropane, trishydroxymethylaminomethane, pentaerythritol, dipentaerythritol And the like.

It is possible to use such a polyester resin as the easy adhesive layer 3 by polymerizing such a carboxylic acid component and a hydroxyl group component according to a conventional method.

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

Examples of the hydroxyl group component include polyethylene glycol, polypropylene glycol, polyether polyol having ethylene oxide and propylene oxide added thereto, and polymer polyol such as acryl polyol and polybutadiene polyol.

The isocyanate compound may be the same as the polyisocyanate compound (C) to be described later. Trimethylene diisocyanate (TDI), hexamethylene diisocyanate (HDI), methylenebis (4,1-phenylene) = diisocyanate (MDI), 3-isocyanatomethyl-3,5,5-trimethylcyclohexylisocyanate ) And xylene diisocyanate (XDI), trimethylolpropane adducts of such diisocyanates, trimerized isocyanate compounds of such diisocyanates, biuret conjugates of such diisocyanates, and polymeric isocyanates.

(A) CH ₂ = CR ₁ -CO-OR ₂ (R ₁ is a hydrogen atom or a methyl group, and R ₂ is a hydroxyl group or a hydrocarbon group having 1 to 20 carbon atoms), which is a monomer constituting the acrylic resin of the easy adhesive layer (3) Methyl acrylate, isopropyl acrylate, n-hexyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, 4-hydroxybutyl acrylate, Hydroxypropyl acrylate, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, butyl methacrylate, n-hexyl methacrylate, lauryl methacrylate, 2-hydroxyethyl methacrylate, 4-hydroxybutyl acrylate, 4-hydroxybutyl methacrylate, hydroxypropyl methacrylate, and the like. Further, it is also possible to use an acrylamide, methacrylamide, acrylonitrile, methacrylonitrile, N-methylol acrylamide, N-alkylolamide, diacetone acrylamide, diacetone methacrylamide, acrolein, methacrolein, glycidyl Methacrylate and the like may be exemplified as a reactive monomer. It may be used in the present invention that these monomers are copolymerized with a predetermined acrylic resin according to a conventional method.

The adhesive agent containing a crosslinking agent is used to improve the toughness, stretchability, heat resistance, moisture resistance and weather resistance of the easy adhesive layer 3 and the adhesive material for the non-light receiving surface side sealing material IV and the protective sheet V When forming the solar cell module by bonding, it is preferable to crosslink the crosslinking agent-containing easy adhesive layer 3 on the outermost surface of the protective sheet (V) in the case of the solar cell. For example, when the polyester resin, the urethane resin, and the acrylic resin exemplified above are used for the easy adhesive layer 3, the resin has a reaction point such as a hydroxyl group, a carboxyl group, a sulfonyl group, a phosphonyl group, an isocyanate group, .

Examples of the crosslinking agent include a polyisocyanate compound, a polycyanate compound, a polyglycidyl compound, and a polyaziridyl compound.

From the viewpoints of durability and coating stability, an isocyanate compound is preferable as a curing agent having a functional group capable of reacting with a polyester-based or urethane-based resin having a hydroxyl group and an isocyanate hydroxyl group. In view of durability improvement, a polyisocyanate compound is preferable. A blocked polyisocyanate compound may also be used. As the polyisocyanate compound, the same polyisocyanate compound as the crosslinking agent of the acrylic resin can be used.

Examples of the crosslinking agent include oxazoline compounds other than the above polyisocyanate compounds such as 2,5-dimethyl-2-oxazoline, 2,2- (1,4-butylene) -bis (2-oxazoline) A zwitteride compound such as isophthalic acid dihydrazide, sebacic acid dihydrazide, adipic acid dihydrazide.

In the case of a solar cell, the protective sheet may have a water vapor barrier layer imparting moisture resistance. The vapor barrier layer is not particularly limited, but may be a metal foil or a metal oxide or a non-metal inorganic oxide deposited layer.

As the metal foil, aluminum foil, iron foil, zinc foil, or the like can be used. Of these, aluminum foil is preferable from the viewpoint of corrosion resistance, and the thickness is preferably 10 to 100 mu m, more preferably 20 to 50 Mu m. A variety of conventionally known adhesives can be used for the lamination of both.

The vapor deposition layer is provided on one side of the plastic film (2). A laminate of the cross-sectionally-deposited polyester films laminated through the interlayer adhesive layer, or a laminate of the cross-sectionally deposited polyester film and another vapor-deposited film through the interlayer adhesive layer can also be used.

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

The water vapor barrier layer may be a laminate obtained by laminating two or more of the barrier layers according to necessary electrical insulation and water vapor barrier.

Examples of the method for 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 include a roll knife coater, a die coater, a roll coater, a bar coater, a gravure roll coater, A method of coating a weather-resistant flame retardant resin composition (1 ') or an easy adhesive composition (3') by a conventionally known coating method such as a coater, a dipping blade coater, a gravure coater, a microgravure coater or a comma coater, A method of bonding the film formed from the composition (1 ') or the easy adhesive composition (3') to the plastic film (2) or the water vapor barrier layer by a conventionally known laminating method such as dry lamination, extolerance lamination or thermal lamination have.

Next, a method for manufacturing a protective sheet for a solar cell backing of the present invention will be described. 2A is a schematic cross-sectional view showing an example of a solar cell backing sheet of the present invention in which a weather resistant flame retardant resin layer 1, a plastic film 2, and an easy adhesive layer 3 are laminated. The solar cell backing sheet of the present invention may further include a water vapor barrier layer 4, an interlayer adhesive layer 5, and the like. For example, FIG. 2B is a cross-sectional view of an embodiment of the present invention in which the weather resistant flame retardant resin layer 1, the water vapor barrier layer 4, the interlayer adhesive layer 5, the plastic film 2 and the easy adhesive layer 3 are laminated. Sectional view showing an example of a backsheet of a battery. 2C is a cross-sectional view of a photovoltaic cell according to the present invention in which a weather resistant flame retardant resin layer 1, a plastic film 2, an interlayer adhesive layer 5, a water vapor barrier layer 4 and a facilitating adhesive layer 3 are laminated. Fig. 2 is a schematic cross-sectional view showing an example of a sheet.

Next, a manufacturing method of the solar cell module of the present invention will be described. The solar cell module of the present invention comprises a solar cell surface sealing sheet (I) positioned on the light receiving surface side of a solar cell, a sealing material layer (II) located on the light receiving surface side of the solar cell, a solar cell element The sealing material layer (IV) located on the non-light-receiving surface side of the solar cell and the above-described solar cell backing sheet of the present invention as an essential constituent layer, and the weather resistant flame retardant resin layer 1) is located farthest from the solar cell surface sealing sheet (I). That is, by stacking the solar cell backing sheet so that the easy adhesive layer 3 constituting the protective sheet is in contact with the non-light-receiving surface side encapsulant layer IV of the solar cell of the present invention, Can be obtained. When the non-light-receiving surface side encapsulant layer (IV) and the solar cell are laminated with the protective sheet, they are brought into contact with each other under reduced pressure and then superimposed under heating and pressing. If the easy adhesive layer 3 is thermosetting, the hardening of the easy adhesive layer 3 may be advanced again under high temperature conditions after returning to normal pressure.

[Example]

Hereinafter, the present invention will be described in more detail with reference to Examples. In the examples, parts represent parts by weight, and% represents weight%. The symbols in the table are as follows.

Phosphorus flame retardant A1: Exolit OP930 (aluminum tris diethylphosphinate, manufactured by Clariant)

Phosphorus flame retardant A2: Exolit OP1230 (aluminum tris diethylphosphinate, manufactured by Clariant)

Phosphorus flame retardant A3: Exolit OP1312 (mixture of trisdiethylphosphinic acid aluminum and phosphoric acid melamine, manufactured by Clariant)

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

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

Phosphorous flame retardant A6: FP-300 (4-cyanophenoxycyclotriphosphazene, manufactured by Fusumi Pharmaceutical Co., Ltd.)

Phosphorus flame retardant A7: Formerel 100 (melamine phosphate, manufactured by Hitachi Chemical Co., Ltd.)

Lining agent A8: Formerel 200 (melamine phosphate dimer, manufactured by Hitachi Chemical Co., Ltd.)

Phosphorus flame retardant A9: Ammonium polyphosphate

Phosphorous flame retardant A10: Triphenylphosphate (manufactured by Daihachi Chemical Industry Co., Ltd.)

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

Non-phosphorus flame retardant A12: Aluminum hydroxide

Halogen-based flame retardant A13: fire cut FCP-83D (decabromodiphenyl oxide, manufactured by Suzuki Chemical)

Fluorine-based resin B1: PVDF emulsion solution (made by Alake)

Fluorine-based resin B2: PVDF pellet (KYNAR, AkeMassa)

Urethane resin B3: Urethane resin solution (SANFOREN Co., Ltd.)

Polyester resin B4: Polyester resin pellets (Toyobo Co., Byron, intrinsic viscosity of 0.52 (dl / g), cyclic trimer content of 1.5% by weight)

Polyester resin B5: Polyester resin pellet (Toyobo Co., Ltd. Byron) was obtained by removing a low oligomer component from a low-speed sieve extractor (having an intrinsic viscosity of 0.67 (dl / g) and a cyclic trimer content of 0.5 wt%).

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

TAI-PACK CR-97: Ishihara Industrial White Titanium Oxide Titanium Oxide

<Preparation of weather-resistant flame retarding films (1 to 14, 101, 102, 23, 25 to 31)

The phosphorus flame retarding agent (A), the weather-resistant resin (B) and the pigment (C) were mixed at a solid composition ratio shown in Tables 1A and 1C and dissolved in a toluene / ethyl acetate 50/50 mixed solvent to have a solid content of 50%. After that, the resultant was dispersed in a paint disperser to obtain a weather resistant flame retardant resin solution (1 to 14, 101 to 102, 23, 25 to 31).

The weather-resistant flame retardant resin solutions (1 to 14, 101 to 102, 23 and 25 to 31) were coated on the peeled polyethylene terephthalate (hereinafter referred to as Saper PET) with an applicator and the solvent was volatilized, A coating film was obtained and peeled from the separator PET to produce a weatherproof flame retardant film.

<Preparation of weatherable flame retarding films (15 to 22, 103 to 108, 32, and 33 to 39)

The phosphorus flame retarding agent (A), the weather-resistant resin (B) and the pigment (C) were mixed in the compositions shown in Table 1B and Table 1C and preliminarily mixed using a tumbler (SKS50, manufactured by Shin Eigou Co.). Subsequently, the mixture was kneaded and extruded using a twin-screw extruder (manufactured by Fla., Japan), followed by premixing using a tumbler (SKS50, manufactured by Shin-Ei Engineering Machinery Industry Co., Ltd.). Subsequently, the mixture was kneaded and extruded using an axial extruder (manufactured by Japan Puracon Co., Ltd.), and then cut with a pelletizer to obtain a resin composition in the form of a pellet. The resin composition thus obtained was extrusion-molded into a sheet using a T-die extruder to produce a weather resistant flame retardant film having a thickness of 30 占 퐉.

&Lt; Flammability measurement: UL test >

Weatherable flame retardant films (1 to 23, 25 to 32, 34 to 39, and 101 to 108) having a thickness of 30 占 퐉 were evaluated by HB standard or V standard prescribed in UL-94.

<< HB Specification >> A strip test specimen is horizontally placed, burned with a burner flame at one end, and passed at the speed at which the combustion proceeds. In the case of a weather-resistant flame retardant film having a thickness of 30 占 퐉, a burning rate of 40 mm / min or less, or 75 mm / min or less, is defined as an HB test "pass".

<< V Standard >> Use 5 test specimens. Hold the burner flame at the bottom of the vertically supported strip test specimen, hold it for 10 seconds, remove the burner flame from the test specimen, and immediately after the flame disappears, let the burner flame fall again for 10 seconds before releasing the burner flame.

The sum of the duration of the flame after the end of the first and second flame contact, the duration of the combustion with the flame remaining after the second flame contact, and the duration of the combustion without flame, And the time when the combustion is continued, and the presence or absence of the combustion load (drip). Specifically,

V-0: No flaming drops (drip), and the first and second flames are in contact with each other after the end of the flame contact, and the duration of the combustion is within 10 seconds. The sum of the burning time is less than 30 seconds, and the sum of the burning time of the flame of 5 test pieces is less than 50 seconds.

V-1: There is no drop (drip), and the first and second flames are in contact with the flame after the end of the flame. The duration of the flame is 30 seconds or less. The sum of the burning time is less than 60 seconds, and the sum of the burning time with five flames of the test piece is less than 250 seconds.

V-2: Same as V-1 except that there is a fall-off (drip).

Since the HB and V standards are different standards, direct comparisons can not be made. However, the V standards are strict standards compared to the HB standards, and even if they pass the HB standards, they may be lower than the V standards of the V standards. Therefore, the better and worse the flame retardancy is, the better it gets to the left as follows.

> V-0> V-1> V-2> Passed HB> HB failed

The results are shown in Table 2

&Lt; Fabrication of protective sheet 1 for solar cells >

On both sides of a polyester film (Tetron S, thickness 188 占 퐉), a polyester adhesive "Dainareo VA-3020 / HD-701" (manufactured by Toyoko Ink SC Holdings Co., Ltd., compounding ratio 100 / 7, the same applies hereinafter) was applied by a gravure coater, and the solvent was dried to provide an interlayer adhesive layer having a coating amount of 10 g / m 2. On this interlayer adhesive layer, a vapor deposition surface of vapor-deposited PET (manufactured by Mitsubishi Plastics, Tech Barrier LX, thickness: 12 mu m) was overlapped. Thereafter, the film was subjected to aging treatment at 50 占 폚 for 4 days, and the interlayer adhesive layer was cured to prepare a laminate of polyester film-deposited PET. The deposited PET was a vapor deposited PET produced by vacuum deposition of silica.

Next, the weather-resistant flame retardant resin solution 1 described in Table 1A was applied to the polyester film surface of the polyester film-deposited PET laminate, and the solvent was dried to provide a weather-resistant flame retardant resin layer having a film thickness of 15 탆. Thereafter, the film was subjected to an aging treatment at 40 占 폚 for 3 days to cure the weather-resistant flame retardant resin layer to produce a weather-resistant flame retardant resin layer-polyester film-deposited PET laminate. Then, a polyester adhesive "Dainareo VA-3020 / HD-701" was applied to the surface of the deposited PET by a gravure coater and the solvent was dried to provide an easy adhesive layer having a coating amount of 5 g / m 2 (thickness: 5 μm) A protective sheet 1 was produced on the back surface of a battery.

<Fabrication of Protective Sheets 2 to 14, 101 to 102, 23 and 25 to 31 on the Back of Solar Cells>

In the case of a solar cell, the protective sheets 2 to 14, 101 to 101, and 101 to 102 were formed by using the same weather resistance flame retardant resin solutions 2 to 14, 101 to 102, 23 and 25 to 31 shown in Tables 1A and 1C, 102, 23 and 25 to 31 were prepared.

<Fabrication of solar cell backing sheet 15>

In the case of a solar cell, a polyester film-deposited PET laminate was first produced by the same manufacturing method as that of the protective sheet 1.

Subsequently, a polyester adhesive "Dynareo VA-3020 / HD-701" was applied to the polyester film side of the polyester film-deposited PET laminate by a gravure coater, and the solvent was dried to obtain a laminate having a coating amount of 10 g / An adhesive layer was provided. A weather resistant flame retardant film (thickness: 30 mu m) described in Table 1B was stacked on this interlaminar adhesive layer. Thereafter, the film was subjected to an aging treatment at 50 占 폚 for 4 days to cure the weather-resistant flame retardant resin layer to prepare a weather-resistant flame retardant resin layer-polyester film-deposited PET laminate. Then, a polyester adhesive "DINAREA VA-3020 / HD-701" was applied to the surface of the evaporated PET by a gravure coater and the solvent was dried to provide an easy adhesive layer having a coating amount of 5 g / , And a solar cell back protection sheet 15 were produced.

<Fabrication of Protective Sheets 16 to 22, 103 to 108, 32, and 34 to 39 on the Back of Solar Cells>

Using the weatherproof flame retarding films 16 to 22, 103 to 108, 32 and 34 to 39 shown in Table 1B and Table 1C in the same manner as in the solar cell rear protective sheet 15, the solar cell backing protective sheets 16 to 22, 103 to 108 and 32 , 34 ~ 39 were produced.

&Lt; Fabrication of solar cell backing sheet 40 >

Resistant flame retarding film having the same composition as that of the weather-resistant flame-retarding film 15 and having the same composition as that of the protective sheet 15, and a weather-resistant flame retardant resin layer, a polyester film- A protective sheet (40) was fabricated for a solar cell having a layer structure of easy adhesive layer.

<Fabrication of solar cell backing sheet 41>

A solar cell backing sheet 41 having a layer structure of a polyester film-deposited PET-easy adhesive layer was produced by the same manufacturing method as that of the protective sheet 15 except that the weather resistant flame retardant resin layer was not provided.

[Example 1]

When the solar cell was used, the protective sheet 1 was used to evaluate cross-cut adhesion, combustibility, moisture resistance, and weather resistance in the manner described below.

&Lt; Cross-cut adhesion measurement >

The cross-cut adhesion was evaluated as follows: when a solar cell was used, the weather-resistant flame retardant resin layer of the protective sheet 1 was wound in a cross-like shape with a cutter and subjected to a cellophane tape peeling test to visually observe the state of the remaining coating film after peeling the cellophane tape, Layer was evaluated for adhesion to the polyester film.

O: There is no peeling of the peripheral portion of the wound.

[Delta]: There is a slight tendency to peel off the periphery of the wound.

X: Clear peeling is observed in the peripheral portion of the wound.

&Lt; Flammability measurement: Radiant panel (RP) test >

Flammability was evaluated according to ASTM-E162 and flame propagation test (radiant panel test) was carried out to calculate the heat release coefficient from the flame spreading factor and the combustion temperature from the burning rate, and the product was taken as the flame propagation index. In the flame propagation test, a solar cell is exposed to a protective sheet in the presence of a radiant panel at 600 DEG C, and a solar cell is irradiated with a protective sheet at a burning rate of the flame, Evaluation method. The UL1703 standard value is 100 or less, and if it exceeds 100, it is rejected.

○: less than 50

?: 50 or more to less than 100

X: 100 or more and less than 150

× ×: 150 or more

<Humidity Resistance Test>

The resistance to humidity resistance was evaluated by using a pressure cooker tester under the conditions of a temperature of 105 ° C, a relative humidity of 100% RH and a pressure of 2 atm for 96 hours, 192 hours and 288 hours, and the crosscut adhesion, yellowing degree and combustibility (RP test) were evaluated. The crosscut adhesion was evaluated based on the above-described method and standard. The yellowing degree was measured on the weatherproof flame retardant resin layer side of the protective sheet 1 using a color chromaticity meter CR-300 (manufactured by Konica Minolta Co., Ltd.) according to the method described in JIS-Z8722, and was expressed by an L * a * b * Was evaluated by the value of? B.

∘: Δb value less than 2

?:? B value of 2 or more and less than 4

×: Δb value 4 or more and less than 10

× ×: Δb value of 10 or more

The flammability (RP test) was evaluated based on the above-described method and criteria.

&Lt; Weather test >

The weather resistance was evaluated by cross-cut adhesion, yellowing, and film reduction in 10 cycles (that is, after 120 hours) under the following conditions using an Iso Super UV tester (manufactured by Iwasaki Electric Co., Ltd.).

(Weathering test conditions)

1) 63 ℃ 70% 90mW / ㎠ irradiation 4 hours

2) 70 ° C 90% static 4 hours

3) 10 seconds of shower → 4 hours of condensation → 10 seconds of shower

4) Repeat 10 cycles of 1), 2) and 3) in one cycle (120 cycles in 10 cycles of 12 hours and 1 cycle)

&Lt; Membrane Reduction > A part of the surface of the weather-resistant flame-retardant resin layer of each test piece was protected with weather-resistant tape, and the level difference between the protective portion and the unprotected portion was measured after 10 cycles.

?: Film thickness less than 1 占 퐉

DELTA: Film reduction is 1 占 퐉 or more and less than 5 占 퐉

X: film thickness is not less than 5 占 퐉 and less than 10 占 퐉

占 占: film reduction of 10 占 퐉 or more

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

In the same manner as in Example 1, the crosscut adhesion, combustibility, moisture resistance and weatherability were evaluated using the protective sheets 2 to 14, 101, 102 and 23, 25 to 31 on the back side of the solar cell. Table 3 shows the above results.

[Example 15]

The protective sheet 15 was used as a solar cell, and the burnability, heat resistance, and weather resistance were evaluated in the same manner as in Example 1. In addition, since the protective sheet 15 can not evaluate the crosscut adhesion of the solar cell using the weather-resistant flame retardant film, the toughness of the weather-resistant resin layer was evaluated by a method described later.

&Lt; Measurement of toughness &

In the case of a solar cell, the protective sheet 15 was cut into a 15 mm-wide rectangular test piece. For each of the test pieces, a T-shaped peeling test was carried out between a weather-resistant flame retardant resin layer (i.e., weather-resistant flame-retardant film) and a polyester film at a load speed of 100 mm / min using a tensile tester and when the weather- .

○: 3N / 15mm or more

?: 0.5 N / 15 mm or more to less than 3 N / 15 mm

X: less than 0.5 N / 15 mm

X: The weather-resistant flame-retardant resin layer (1) is brittle and can not be tested and evaluated.

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

Evaluation of toughness, moisture resistance and weatherability of the weatherproof flame-retardant resin layer and evaluation of the burning property of the protective sheet on the back surface of a solar cell were carried out using the protective sheets 16 to 22 and 32 and 34 to 41 on the back side of the solar cell in the same manner as in Example 15. Table 4 shows the above results.

[Table 1A]

[Table 1B]

[Table 1C]

[Table 2]

[Table 3]

[Table 4]

 Examples 1 to 22 and 101 to 108 (when weatherable flame retardant resin solutions 1 to 14, 101 to 102 or weather-resistant flame retardant resin films 15 to 22 and 103 to 108 were used) as shown in Tables 3 and 4, The flammability test by the test showed excellent flame resistance. That is, according to this embodiment, the weather-resistant flame retardant resin layer 1 having a thickness of 1/5 or less of that of the protective sheet in the solar cell suppresses the combustion of the plastic film 2 as the main constituent member, , And UL-1703. Also, it exhibits excellent adhesion before and after the resistance to humidity and heat resistance test and weather resistance, and is hardly yellowed even after the resistance to humidity and heat resistance and weatherability, and it is hard to decrease the thickness of the coating film and film even after the weather resistance test. It is also possible to exhibit a good value in a flame propagation test after moist heat. That is, the protective sheet of the solar cell of Examples 1 to 22 and the like is a protective sheet if it is a perfect solar cell.

Particularly, in Examples 1 to 3, 5 to 8 and 15 to 16 in which phosphinic acid aluminum or phosphazene was used, hydrophilicity of the weatherable flame retardant resin layer 1 was high, 1, 3 and 10, 12 (when the weather-resistant flame retardant resin solution 23, 25 or the weather-resistant flame retardant resin film 32, 34 were used).

Further, 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 show excellent results in the flame retardancy test specified in UL-94.

On the other hand, Comparative Examples 1, 3, 10, and 12 do not contain phosphorus-based flame retardants and thus have poor flame retardancy and do not satisfy the flammability test standard specified in UL-94. Particularly, as shown in Table 2, 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 resin film 32) -0 and has excellent results. However, the weather resistant flame retardant film does not have the function of suppressing the flammability of the plastic film (2) which is the layer constituting the back surface protective sheet for the solar cell, that is, the comparative example, and has no flame retarding or anti-flammability effect. As a result, in the flame propagation test specified in ASTM E162 as shown in Tables 3 and 4, when evaluating the combustibility of a solar cell as a protective sheet, it does not satisfy the UL-1703 standard.

In Comparative Examples 4, 6 and 14 (using weather-resistant flame retardant resin solutions 26 and 28 or weather-resistant flame retardant film 36), ammonium polyphosphate was used as a phosphorus flame retardant and Comparative Examples 5, 13 and 15 Films 35 and 37 are used), triphenyl phosphate is used as the phosphorus flame retardant, respectively. Therefore, flame retardancy is evaluated in flammability evaluation by the flame propagation test. However, a large deterioration is seen in the wet heat test. That is, it can be seen that phosphoric acid which is a strong acid generated by hydrolysis of ammonium polyphosphate and triphenyl phosphate in the wet heat test deteriorates and weathering the weather resistant flame retardant resin layer 1 and 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 retarding film 38), melamine cyanurate or aluminum hydroxide was used as the flame retardant agent and the weatherability and moisture resistance were not so great . However, the melamine cyanurate and aluminum hydroxide do not form a carbonized film, unlike the phosphorylated flame retardant which forms a carbonized film and exhibits flame retardancy, so that the flame retarding effect is insufficient. In addition, if the blending amount of such a flame retardant is increased in order to improve the flame retardancy, the weather-resistant resin (1) is relatively decreased, and it is difficult to manufacture the weather-resistant flame retardant resin layer (1) itself and it is expected that the weather resistance and moisture- .

Further, in Comparative Example 9 (using the weather-resistant flame retardant resin solution 31), since an acrylic resin containing benzotriazole as the weather-resistant resin (B) and having a hydroxyl value of 38 was used, Resistant flame retardant resin layer (1) even when a phosphinic acid salt having excellent heat and humidity resistance is used, since the flame retardant resin layer (1) exhibits excellent physical properties at the initial stage due to the use of a salt, And the flame retardancy after the wet heat test can not be retained.

In addition, in Comparative Example 17 (using the weather-resistant flame retarding film 39), decabromodiphenyl ether, which is a halogen-based flame retardant, is used as a flame retardant, and there is no great problem in flame retardancy. However, when the weather resistance test or the humid heat test is carried out, it is significantly yellowed. Therefore, it is not suitable for applications where the solar cell module is always exposed to light, heat and humidity.

In Comparative Example 18 (using the weather-resistant flame retarding film 40), since the film thickness t of the weather-resistant flame retardant resin layer 1 is too thin compared to the total film thickness of the protective sheet in the case of a solar cell, the effect of flame retardation is not obtained.

In Comparative Example 19 (using the weather-resistant flame-retardant resin film 41), since the weather-resistant flame-retardant resin layer 1 is not provided, the plastic film 2 is exposed on the surface and the weatherability is remarkably decreased.

In Example 9 (using the weather-resistant flame retardant resin solution 9), the flame retardancy in the flame propagation test was somewhat lowered because of the small total phosphorus concentration. Examples 10 and 18 (using the weather-resistant flame retardant resin solution 10 or the weather- ), The amount of the phosphorus flame retardant (A) to be added is large and the total amount of the weather-resistant resin (B) is relatively decreased, so that the weather resistance and the heat and humidity resistance are deteriorated. Further, in Examples 101-104 (using the weather-resistant flame retardant resin solution 101-104), the addition amount of the phosphorus-based flame retardant was small, and the flame retardancy in the flame propagation test was somewhat deteriorated.

In Examples 11 to 14 (using weather-resistant flame retardant resin solutions 11 to 14), a urethane resin was used as weather-resistant resin (B), and in Examples 19 to 22 (weather-resistant flame retardant resin films 19 to 22 were used) It is somewhat less resistant to humidity and heat and weather than when using a fluorine-based resin. However, in Examples 11, 12, 19 and 20 using phosphine acid aluminum or phosphazene, the hydrophobicity of the weather-resistant flame retardant resin layer (1) was increased. Thus, in Examples 13, 14, 21 and 22 using melamine phosphate outstanding. In addition, since Examples 105 to 108 (using Weather Resistant Flame Retardant Resin Films 105 to 108) use a polyester resin having an intrinsic viscosity of 0.67 (dl / g) and a cyclic trimer content of 0.5% by weight, It is superior in weather resistance and heat and humidity resistance than ester type resin, and is excellent as weather resistant flame retardant resin layer.

This application claims priority based on Japanese Patent Application No. 2011-170505 filed on August 3, 2011, Japanese Patent Application No. 2012-096934 filed on April 20, 2012, and the entire publication is inserted here .

I: a solar cell surface seal sheet positioned on the light receiving surface side of the solar cell
II: an encapsulating material layer located on the light receiving surface side of the solar cell
III: Photovoltaic cell device
IV: sealing material layer located on the non-light-emitting surface side of the solar cell
V: solar cell backing sheet
1: weather-resistant flame-retardant resin layer
2: Plastic film
3: Adhesive layer
4: Water vapor barrier layer
5: Interlayer adhesive layer

Claims (5)

A solar cell backing sheet comprising a weatherproof flame retardant resin layer (1) having a film thickness t (占 퐉), a plastic film (2) and a easy adhesive layer (3)
Wherein the weather resistant flame retardant resin layer (1) constitutes one side of the protective sheet on the back side of the solar cell, the easy adhesive layer (3) constitutes the other side of the protective sheet on the back side of the solar cell,
Wherein the weather resistant flame retardant resin layer (1) comprises a phosphorus flame retardant (A) selected from the group consisting of a phosphazene compound, a phosphinic acid compound and a (poly) phosphoric acid melamine, and a fluororesin, a urethane resin and a polyester resin (B) selected from the group consisting of
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 protective sheet in the case of a solar cell,
Wherein the total phosphorus concentration derived from the phosphorus flame retardant (A) in the weather-resistant flame retardant resin layer (1) is 2.1 to 14.2 wt%. The backsheet for a solar cell backsheet according to claim 1, wherein the weather resistant flame retardant resin layer (1) comprises 20 to 50 wt% of the phosphorus flame retardant (A). The solar cell back protective sheet according to claim 1 or 2, wherein the total phosphorus concentration derived from the phosphorus-based flame retardant (A) of the weatherable flame retardant resin layer (1) is 3 to 10% by weight. The said weatherable resin (B) is fluorine-type resin or the low oligomeric polyester-type resin of Claim 1 or 2 whose intrinsic viscosity is 0.6 (dl / g) or more and whose cyclic trimer content is 1 weight% or less. The solar cell back surface protection sheet characterized by the above-mentioned. A sealing material layer (II) located on the light receiving surface side of the solar cell, a solar cell element (III) positioned on the light receiving surface side of the solar cell, an encapsulating material A solar cell module comprising the solar cell backsheet (V) in contact with the layer (IV) and the non-light-receiving surface side encapsulant layer (IV) according to any one of claims 1 to 4,
A weather resistant resin layer (1) constituting a protective sheet of the solar cell is located farthest from the solar cell surface sealing sheet (I).

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