JP5352703B2 - Solar cell back surface protection sheet and solar cell module - Google Patents

Abstract

Provided is an inexpensive solar cell rear surface protective sheet having flame-retardant properties that satisfy the UL-1703 spread of flame test, and excellent long-term resistance to moist heat and long-term resistance to outdoor weather. This solar cell rear surface protective sheet is equipped with a film-thickness (t), weather-resistant, flame-retardant resin layer (1), a plastic film (2), and an easy-adhesion layer (3). Therein, the weather-resistant, flame-retardant resin layer (1) comprises the surface on one side of the solar cell rear surface protective sheet, while the easy-adhesion layer (3) comprises the surface on the other side thereof. The weather-resistant, flame-retardant resin layer (1) contains: a phosphorous-based flame retardant (A) selected from a group consisting of a phosphazene compound, a phosphinic acid compound, and a melamine (poly)phosphate; and a weather-resistant resin (B) selected from a group consisting of a fluorine resin, a urethane resin, and a polyester resin. The film thickness (t) of the weather-resistant, flame-retardant resin layer (1) is set at 2.5-20% of the total thickness, while the total phosphorous concentration deriving from the phosphorous-based flame retardant (A) contained in the weather-resistant, flame-retardant resin layer (1) is set at 2.1-14.2 wt%.

Description

  The present invention relates to a solar cell back surface protective sheet comprising a weather resistant flame retardant resin layer, an adhesive layer and a plastic film. Specifically, the present invention relates to a solar cell back surface protective sheet that is inexpensive and has flame retardancy, scratch resistance, long-term wet heat resistance, and long-term outdoor weather resistance. Furthermore, this invention relates to the solar cell module which uses the said solar cell back surface protection sheet.

In recent years, solar cells have been attracting attention as a clean energy source free from environmental pollution due to an increase in awareness of environmental problems, and earnestly researched and put into practical use from the viewpoint of using solar energy as a useful energy resource.
There are various types of solar cell elements, and typical examples thereof include a crystalline silicon solar cell element, a polycrystalline silicon solar cell element, an amorphous silicon solar cell element, a copper indium selenide solar cell element, and a compound semiconductor solar. Battery elements and the like are known.

  A simple one of the solar cell modules has a configuration in which a filler and a glass plate are sequentially laminated on both sides of the solar cell element. Since a glass plate is excellent in transparency, weather resistance, and scratch resistance, it is still generally used as a sealing sheet on the solar light receiving surface side. However, on the non-light-receiving surface side that does not require transparency, solar cell back surface protection sheets other than glass plates have been developed by various companies from the viewpoints of cost, safety, and workability, and are being replaced by glass plates.

As the back surface protection sheet, a monolayer film such as a polyester film, a polyester film provided with a metal oxide or non-metal oxide vapor deposition layer, a polyester film, a fluorine-based film, an olefin film, an aluminum foil, etc. A multilayer film obtained by laminating films is mentioned (Patent Documents 1 to 3 ).

Solar cell back surface protective sheet outermost layer, i.e. the layer situated farthest from the light-receiving surface, a fluorine-based solar cell back surface protective sheet comprising a resin film are laminated is known which has a weather resistance and flame retardancy ( Patent Documents 4 and 5).

Po the weathering layer to re ester film, a fluorine-based resin or an acrylic resin solar cell back surface protective sheet for a coating layer provided to impart weather resistance has been known (Patent Documents 6 and 7).

In addition, by providing a coating layer containing a phosphorus-based or inorganic flame retardant on a thermoplastic resin film having no flame retardancy, it is specified in UL-94 of the US UNDERWRITERS LABORATORIES standard (hereinafter abbreviated as UL). The laminated film which has the flame retardance level equivalent to HB and V-2 which were made is proposed, and the use called a solar cell is also proposed (patent documents 8-11).
By the way, the flame retardance calculated | required by the solar cell back surface protection sheet is a flame propagation test (radiant panel test, ASTM E162) prescribed | regulated to UL-1703. Even the laminated film having the flame retardancy level equivalent to HB and V-2 according to the above-mentioned regulations of UL-94 could not satisfy the requirements of the flame propagation test defined in UL-1703.
Moreover, the laminated film having the flame retardancy level equivalent to HB and V-2 described above was insufficient in terms of heat and humidity resistance defined in UL-1703.

In addition, although it is a patent document published after the previous application that is the basis of the priority, as a coating agent for imparting flame retardancy to the solar cell back surface protection sheet, an inorganic pigment and a flame retardant are added to the fluororesin. The coating agent to contain is proposed (patent document 12).
However, the flame retardants exemplified therein are melamine cyanurate, guanidine compounds, triazine compounds, hindered amine compounds, aromatic phosphate esters, aromatic condensed phosphate esters, and hydrated metal compounds, and these flame retardants are used. If it was, the requirements of the flame propagation test specified in UL-1703 could not be satisfied.

Japanese Patent Laid-Open No. 2004-200322 JP 2004-223925 A JP 2001-119051 A JP 2003-347570 A JP 2004-352966 A JP 2008-098592 A Special table 2010-519742 gazette JP 2009-179037 A JP 2010-89334 A JP 2010-120321 A JP 2010-149447 A JP 2011-162598 A

  An object of the present invention is to overcome the conventional problems, and is inexpensive and has a flame retardancy, long-term wet heat resistance, and long-term outdoor weather resistance, and a solar cell using the solar cell back-surface protection sheet Is to provide modules.

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 easy adhesive layer (3),
The weather resistant flame retardant resin layer (1) constitutes one surface of the solar cell back surface protective sheet, and the easy adhesive layer (3) constitutes the other surface of the solar cell back surface protective sheet,
A phosphorus-based flame retardant (A) selected from the group consisting of a phosphazene compound, a phosphinic acid compound, and a (poly) melamine phosphate, a fluorine-based resin, a urethane-based resin, and a polyester. Containing a weather resistant resin (B) selected from the group consisting of resin
It is related with the solar cell back surface protection sheet characterized by the film thickness t of a weather-resistant flame-retardant resin layer (1) being 2.5 to 20% of the total film thickness of a solar cell back surface protection sheet.

  It is preferable that the phosphorus-based flame retardant (A) in the weather-resistant flame-retardant resin layer (1) is contained in an amount of 20 to 50% by weight, and the total phosphorus concentration derived from the phosphorus-based flame retardant (A) is 3 to 10% by weight. Preferably there is.

  The weather resistant resin (B) is preferably a fluorine resin.

The present invention provides a solar cell surface sealing sheet (I) positioned on the light receiving surface side of a solar cell, a sealing material layer (II) positioned on the light receiving surface side of the solar cell, solar cells (III), and solar cell A solar cell module comprising the sealant layer (IV) positioned on the non-light-receiving surface side and the solar cell back surface protection sheet (V) in contact with the non-light-receiving surface side sealant layer (IV) Because
The weather-resistant flame-retardant resin layer (1) which comprises the said solar cell back surface protection sheet is located farthest from the said solar cell surface sealing sheet (I), It is related with the solar cell module characterized by the above-mentioned.

  According to the present invention, there is provided a solar cell back surface protective sheet that overcomes the conventional problems, is inexpensive, has excellent flame resistance, long-term moisture and heat resistance, and long-term outdoor weather resistance, and a solar cell module using the solar cell back surface protective sheet. Provided.

It is a figure which shows typically the cross section of the module for solar cells of this invention. It is typical sectional drawing of the solar cell back surface protection sheet of this invention.

The weather-resistant flame retardant resin layer (1) constituting the present invention will be described.
The weather-resistant flame retardant resin layer (1) in the present invention protects the inside of the solar cell back surface protection sheet and further the solar cell module from external factors such as ultraviolet rays and physical impact, and suppresses output deterioration of the solar cell. And the role of imparting flame retardancy to the solar cell back surface protective sheet, which is the most important part in the present invention.

The phosphorus flame retardant (A) contained in the weather resistant flame retardant resin layer (1) will be described.
It is important that the phosphorus-based flame retardant (A) used in the present invention is selected from the group consisting of phosphazene compounds, phosphinic acid compounds, and (poly) melamine phosphate.

The flammability of a general polymer material is evaluated by the time from ignition to extinguishing by the HB test or V (VTM) test specified in UL94.
On the other hand, the standards of flammability of the solar cell module and the solar cell back surface protection sheet are defined in IEC 61730-1, IEC 61730-2 and UL 1703, which are standard standards for solar cells. A propagation test (radiant panel test, ASTM E162) is required. The flame propagation test is evaluated by evaluating both the combustion temperature and the combustion rate of the solar cell back surface protection sheet, and is different from the above HB test or V (VTM) test.

The solar cell back surface protective sheet needs to have a thickness of 250 to 400 μm in order to satisfy the imposed withstand voltage. Therefore, the plastic film (2) which is a main member constituting the solar cell back surface protection sheet is required to have a thickness of 125 to 250 μm. Such a plastic film (2) is often a thermoplastic resin such as a polyester film or an olefin film.
The flame retardant used in the weather resistant flame retardant resin layer (1) of the present invention is difficult for the weather resistant flame retardant resin layer (1) itself which occupies 2.5 to 20% of the total film thickness of the solar cell back surface protective sheet. In addition to imparting flammability, the plastic film (2), which is the main component of the solar cell back surface protection sheet, is prevented from expanding in terms of thickness, and the entire solar cell back surface protection sheet is flameproof and extinguishing. Take on.

Examples of commonly used flame retardants include phosphorus flame retardants, nitrogen flame retardants, silicon flame retardants, and inorganic flame retardants.
As a phosphorus flame retardant,
Phosphate compounds such as melamine phosphate, melamine polyphosphate, guanidine phosphate, guanidine polyphosphate, ammonium phosphate, ammonium polyphosphate, ammonium amidophosphate, ammonium amidophosphate, carbamate phosphate, and carbamate polyphosphate Acid salt compounds,
Examples include red phosphorus, organophosphate compounds, phosphazene compounds, phosphonic acid compounds, phosphinic acid compounds, phosphine oxide compounds, phosphorane compounds, and phosphoramide compounds.

Examples of nitrogen flame retardants include triazine compounds such as melamine, melam, melem, melon, and melamine cyanurate, cyanuric acid compounds, isocyanuric acid compounds, triazole compounds, tetrazole compounds, diazo compounds, urea, and the like.
Examples of silicon flame retardants include silicone compounds and silane compounds.
Examples of halogen flame retardants include halogenated bisphenol A, halogenated epoxy compounds, low molecular halogen-containing compounds such as halogenated phenoxy compounds, halogenated oligomers and polymers,

Examples of inorganic flame retardants include metal hydroxides such as aluminum hydroxide, magnesium hydroxide, zirconium hydroxide, barium hydroxide, calcium hydroxide,
Examples thereof include tin oxide, aluminum oxide, magnesium oxide, zirconium oxide, zinc oxide, molybdenum oxide, antimony oxide, nickel oxide, zinc carbonate, magnesium carbonate, calcium carbonate, barium carbonate, zinc borate, and hydrated glass.

Since solar cell modules are currently required to have a long-term guarantee of 15 to 25 years, long-term weather resistance and long-term moist heat resistance are also required for the solar cell back surface protection sheet, and the weather-resistant flame-retardant resin layer (1). It is said.
Among the above flame retardants, when nitrogen-based flame retardants or inorganic flame retardants are used, flame retardant is not effective in small amounts, so it is necessary to add a large amount. The weather resistance and wet heat resistance of the resin layer (1) are greatly reduced.

Among the above flame retardants, when a halogen flame retardant is used, the weather resistant flame retardant resin layer is greatly yellowed by the moisture and heat resistance test and the weather resistance test. Be repelled. Moreover, since a flame retardant accelerates | stimulates deterioration of a weather resistant resin (B) by a weather resistance test, using for a solar cell back surface protection sheet is not preferable.
In consideration of recent environmental considerations, the use of halogenated flame retardants is not preferred.

Among the above flame retardants, phosphorus-based flame retardants are preferable in that they can exhibit flame retardancy with a relatively small addition amount.
However, among the phosphorus-based flame retardants, it is not preferable to use a flame retardant that is hydrolyzed and generates an acid in the moisture and heat resistance test for the solar cell back surface protective sheet.
For example, when (poly) ammonium phosphate or (poly) phosphate carbamate, which is used for flexible printed circuit boards, is used, it decomposes gradually with the passage of time of the moist heat resistance test and becomes a strong acid phosphorous. Generates acid. The generated phosphoric acid serves as a catalyst for hydrolysis of the weather resistant resin (B), and greatly deteriorates the weather resistant flame retardant resin layer (1).
Therefore, it is important that the phosphorus-based flame retardant used in the solar cell back surface protective sheet is a flame retardant that does not generate acid by hydrolysis. Specifically, if it is a phosphazene compound, a phosphinic acid compound, or a (poly) phosphate melamine, flame retardance can be effectively expressed with a small amount of addition that does not affect weather resistance and heat-and-moisture resistance.

  The phosphorus-based flame retardant (A) selected from the group consisting of phosphazene compounds, phosphinic acid compounds, and (poly) phosphate melamines used in the present invention has high moist heat resistance and can be hydrolyzed over time. Since there is almost no, it is suitable as a flame retardant used for a solar cell back surface protective sheet. Furthermore, phosphazene compounds and phosphinic acid compounds are filler-like compounds with extremely high hydrophobicity. When a phosphazene compound or a phosphinic acid compound is used, the hydrophobicity of the weather resistant flame retardant resin layer (1) can be increased, and higher heat and humidity resistance can be achieved than when the weather resistant resin (B) is used alone. It is extremely suitable as a flame retardant for battery back protection sheets.

  As a phosphazene compound, the phosphazene oligomer illustrated by the following general formula (1) or (2) is mentioned.

However, in the general 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 groups of R ¹ and R ² The group represents a phenyl group, an alkyl group, an amino group, or an allyl group, and the phenyl group and the like may further have a halogen-free substituent. The substituent can be appropriately selected from the group consisting of a hydroxyl group, an amino group, a cyano group, and a nitro group. n is an integer of 3-10.
Cyclophosphazene in which R ¹ or R ² is a phenyl group or an alkyl group is preferable, and cyclophosphazene is more preferably tricyclophosphazene. Specific examples include hexaalkoxytricyclophosphazene and hexaphenoxytricyclophosphazene, and hexaphenoxytricyclophosphazene is preferable.
Examples of the hexaalkoxytricyclophosphazene include hexamethoxytricyclophosphazene, hexaethoxytricyclophosphazene, hexapropoxytricyclophosphazene and the like.
Examples of hexaphenoxytricyclophosphazene include unsubstituted hexaphenoxytricyclophosphazene and hexaphenoxytricyclophosphazene having a substituent such as a hydroxyl group or a cyano group.

  Examples of the phosphinic acid compound include phosphinic acid salts exemplified by the following general formula (3).

However, in General formula (3), R1 and R2 are the same or different, and show a linear or branched alkyl group having 1 to 6 carbon atoms or an aryl group, and M is Mg, Ca, Al , Sb, Sn, Ge, Ti, Zn, Fe, Zr, Ce, Bi, Sr, Mn, Li, Na, K represents an at least one metal selected from the group consisting of 1 to 4 It is. ).
More preferable compounds include phosphinates in which M is Mg, Ca, and Al, and aluminum phosphinates in which M is Al are particularly preferable.
Specifically, trisdialkylphosphinic acid aluminum salt in which R1 and R2 are alkyl groups and n = 3 is preferable.

  Examples of the (poly) melamine phosphate include compounds exemplified by the following general formula (4), in which phosphoric acid and melamine are in a salt state. In the following general formula (4), n is preferably 1 to 10, and the case where n is 2 or more is referred to as “melamine polyphosphate”.

  In the present invention, the above-mentioned phosphorus-based flame retardant (A) can be used alone, and a plurality of compounds selected from each compound group can be used in appropriate combination. Can do.

It is important that 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. That is, in the case of a 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) needs to be in the range of 7.5 to 60 μm. By setting the film thickness t of the weather resistant flame retardant resin layer (1) within the above range, a solar cell back surface protective sheet excellent in flame retardancy and economy can be obtained.
When the film thickness t of the weather resistant flame retardant resin layer (1) is less than 2.5% of the total film thickness of the solar cell back surface protective sheet, the plastic film which is the main constituent member of the solar cell back surface protective sheet in terms of thickness It becomes difficult to suppress the combustion of (2), and the flame retardancy that is an important effect of the present invention cannot be expected so much. On the other hand, when the film thickness t of the weather resistant flame retardant resin layer (1) is 20% or more of the total film thickness of the solar cell back surface protective sheet, it becomes difficult to form a uniform layer, and there is a cost demerit. It gets bigger.

  The weight of the phosphorus-based flame retardant (A) in the weather resistant flame retardant resin layer (1) is preferably 20 to 50% by weight. When the amount of the phosphorus-based flame retardant (A) is in the above range, the flame retardancy, weather resistance, and heat and humidity resistance can be satisfied in a well-balanced manner. When the weight of the phosphorus-based flame retardant (A) is 20% by weight or less, it becomes difficult to suppress the combustion of the plastic film (2), and when it exceeds 50% by weight, the blending amount of the weather resistant resin (B) is relative. Therefore, it tends to be inferior in weather resistance and wet heat resistance.

  The total phosphorus concentration derived from the phosphorus-based flame retardant (A) in the weather-resistant flame-retardant resin layer (1) is preferably 3 to 10% by weight. If the total phosphorus concentration is less than 3%, it is difficult to suppress the flammability of the plastic film (2) even if the flame retardancy of the coating film itself can be expressed, and the standard value of the flame propagation test must be satisfied. difficult. On the other hand, if the total phosphorus concentration exceeds 10%, the amount of phosphorus-based flame retardant (A) added is inevitably increased, and the amount of weathering resin (B) is relatively decreased, so that weather resistance and moisture resistance are increased. It tends to be inferior in heat.

The weather resistant resin (B) constituting the weather resistant flame retardant resin layer (1) will be described.
The weather resistant resin (B) used in the present invention prevents the influence of deterioration due to ultraviolet rays or physical impacts, and the phosphorus flame retardant (A) does not aggregate in the weather resistant flame retardant resin layer (1). It plays the role of a binder that can exist uniformly.

The weather resistant resin (B) is selected from the group consisting of a fluorine resin, a urethane resin, and a polyester resin. Examples of the urethane resin include polyester polyurethane resins, polyether polyurethane resins, polycarbonate polyurethane resins, and urethane resins other than the polyester polyurethane resins. Urethane urea resins having a urea bond in addition to the various urethane resins described above can also be mentioned as urethane resins.
In order to further improve the weather resistance, the weather resistant resin (B) may be combined with an ultraviolet absorber, a light stabilizer, an antioxidant, etc., or the weather resistant resin (B) may be combined with an ultraviolet absorber, light. Stabilizers, antioxidants and the like may be added.

The phosphorus-based flame retardant (A) selected from the group consisting of phosphazene compounds, phosphinic acid compounds, and (poly) phosphate melamines used in the present invention hardly hydrolyzes in the wet heat resistance test. However, even a very small amount of acid generated as a result of slight hydrolysis becomes a catalyst for a very long period of time, and promotes hydrolysis of the weather resistant resin (B). ) May progress.
Therefore, it is preferable that the weather resistant resin (B) does not contain a hydrolyzable site in the main chain of the resin.
Specifically, a fluorine resin is preferable. The fluororesin is excellent in weather resistance and chemical resistance, and is suitable as the weather resistant resin (B).

  On the other hand, in the case of a urethane-based resin, a polyester-based resin, or the like, the main chain has a urethane bond or an ester bond that may be hydrolyzed. Therefore, a trace amount of acid generated from the phosphorus-based flame retardant (A) may become a catalyst and cause hydrolysis over a long period of time, which may deteriorate the weather resistant resin layer (1). When, for example, ammonium phosphate is used for urethane resin or polyester resin, ammonium phosphate is decomposed in a heat and humidity resistance test, and phosphoric acid which is a strong acid is generated. And since the generated phosphoric acid will decompose | disassemble a urethane type resin and a polyester-type resin, a flame retardant like ammonium phosphate is not suitable for a solar cell back surface protection sheet.

  Examples of fluororesins include polytetrafluoroethylene (PTFE), polychlorotrifluoroethylene (PCTFE), polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), perfluoroalkoxy fluororesin (PFA), and tetrafluoroethylene. -Hexafluoropropylene copolymer (FEP), ethylene-tetrafluoroethylene copolymer (ETFE), ethylene-chlorotrifluoroethylene copolymer (ECTFE), etc. are mentioned.

The polyester-based resin is obtained by reacting a carboxylic acid component having a carboxylic acid group with a hydroxyl group component having a hydroxyl group.
The carboxylic acid component constituting the polyester resin includes benzoic acid, p-tert-butylbenzoic acid, phthalic anhydride, isophthalic acid, terephthalic acid, succinic anhydride, adipic acid, azelaic acid, tetrehydrophthalic anhydride, hexahydro anhydride Examples include phthalic acid, maleic anhydride, fumaric acid, itaconic acid, tetrachlorophthalic anhydride, 1,4-cyclohexanedicarboxylic acid, trimellitic anhydride, methylcyclocentricarboxylic anhydride, pyromellitic anhydride, ε-caprolactone, fatty acid it can.
Examples of the hydroxyl group component constituting the polyester resin include ethylene glycol, propylene glycol, 1,3-butylene glycol, 1,6-hexanediol, diethylene glycol, dipropylene glycol, neopentyl glycol, triethylene glycol, and 3-methylpentanediol. In addition to diol components such as 1,4-cyclohexanedimethanol, polyfunctional alcohols such as glycerin, trimethylolethane, trimethylolpropane, trishydroxymethylaminomethane, pentaerythritol and dipentaerythritol can be exemplified.
According to a conventional method, those obtained by polymerizing these carboxylic acid component and hydroxyl group component into a predetermined polyester resin can be used in the present invention.

The urethane-based resin 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 component include polyethylene glycol, polypropylene glycol, polymer polyols such as polyether polyols added with ethylene oxide or propylene oxide, acrylic polyols, and polybutadiene polyols.
As an isocyanate compound, the thing similar to the polyisocyanate compound (C) mentioned later can be illustrated. Trimethylene diisocyanate (TDI), hexamethylene diisocyanate (HDI), methylene bis (4,1-phenylene) = diisocyanate (MDI), 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate (IPDI), xylylene diisocyanate ( XDI), trimethylolpropane adducts of these diisocyanates, isocyanurates that are trimers of these diisocyanates, burette conjugates of these diisocyanates, polymeric diisocyanates, and the like.

  When the weather resistant resin (B) requires high toughness, weather resistance, and moist heat resistance, it can react in the main chain of the weather resistant resin (B) in order to obtain a higher crosslinking density. A functional group may be introduced and crosslinked with a general crosslinking agent.

  Examples of the crosslinking agent include polyisocyanate compounds, polyglycidyl compounds, and polyaziridyl compounds.

  From the viewpoint of durability and coating liquid stability, an isocyanate compound is preferred as the 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. Furthermore, a polyisocyanate compound is preferable from the viewpoint of improving durability.

The polyisocyanate compound is a weather resistant resin that crosslinks the weather resistant resins (B) to each other and has toughness, extensibility, flexibility, molding processability, scratch resistance, long term weather resistance, long term wet heat resistance, and chemical resistance. Used to form a layer.
In order to prevent the resulting weather-resistant resin layer from changing from yellow to brown over time, it is preferable to use only an alicyclic or aliphatic compound.

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

  Examples of the aliphatic polyisocyanate compound include trimethylhexamethylene diisocyanate, hexamethylene diisocyanate, and lysine diisocyanate.

  Examples of the aromatic polyisocyanate compound include diphenylmethane diisocyanate, toluylene diisocyanate, naphthylene-1,5-diisocyanate, o-xylene diisocyanate, m-xylene diisocyanate, p-xylene diisocyanate, triphenylmethane triisocyanate, polymethylene polyphenyl. An isocyanate etc. are mentioned.

As the polyisocyanate compound, a double-ended isocyanate adduct, biuret-modified, or isocyanurate-modified, which is a reaction product of the above-mentioned compound and glycols or diamines, may be used.
In particular, when the polyisocyanate compound contains an isocyanurate-modified product, particularly an isocyanurate ring-containing triisocyanate, it is preferable because a weather-resistant resin layer having toughness and extensibility can be obtained. Specific examples of the isocyanurate ring-containing triisocyanate include isocyanurate-modified isophorone diisocyanate (for example, Desmodule Z4470 manufactured by Sumitomo Bayer Urethane Co., Ltd.), isocyanurate-modified hexamethylene diisocyanate (for example, Sumidur manufactured by Sumitomo Bayer Urethane Co., Ltd.) N3300), isocyanurate-modified toluylene diisocyanate (for example, Sumidur FL-2, FL-3, FL-4, HL BA manufactured by Sumitomo Bayer Urethane Co., Ltd.). In addition, the isocyanate group in one molecule may be increased by reacting with a polyester (c) having two or more functional groups capable of further reacting the isocyanurate ring, or the generated urethane bond and one equivalent of isocyanate. A group may be reacted to form allophanate to further increase the isocyanate group in one molecule. As the polyester (c) having two or more functional groups capable of reacting with an isocyanate group, a known polyester resin can be used.

  The isocyanate group of the polyisocyanate compound is, for example, methanol, ethanol, n-pentanol, ethylene chlorohydrin, isopropyl alcohol, phenol, p-nitrophenol, m-cresol, acetylacetone, ethyl acetoacetate, or ε-caprolactam. You may use the block modified body which made it react with blocking agents, such as, and was made into a block.

Furthermore, as a polyisocyanate compound (as a polyester isocyanate (d) having two or more functional groups capable of reacting with an isocyanate group) and a diisocyanate compound (e) having an isocyanate group at both ends are reacted. In the case where the polyisocyanate compound contains the above-mentioned both-end isocyanate prepolymer, extensibility can be obtained with a small amount and the toughness of the coating film is not impaired.
A polyisocyanate compound can be used 1 type or in combination of 2 or more types.

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

  In the polyisocyanate compound, the number of isocyanate groups of the polyisocyanate compound relative to the total number of functional groups (functional groups reactive with isocyanate groups) of the weather resistant resin (B) is 0.00. It is preferably 1 to 5 times, and more preferably 1 to 3 times. If it is less than 0.1 times, the crosslinking density is too low, and the solvent resistance, scratch resistance and weather resistance are not sufficient, and if it is more than 5 times, the isocyanate is left and reacts with moisture in the air. This is a factor that changes physical properties depending on the season.

  As the curing agent, in addition to the above polyisocyanate compound, well-known oxazoline compounds such as 2,5-dimethyl-2-oxazoline, 2,2- (1,4-butylene) -bis (2-oxazoline) or hydrazide Compounds such as isophthalic acid dihydrazide, sebacic acid dihydrazide, adipic acid dihydrazide can be included.

  The aromatic ring content in the weather resistant resin (B) is at most 50% by weight, preferably 10% by weight or less, and preferably contains no aromatic ring as much as possible. When the aromatic ring content in the weather resistant resin (B) exceeds 50% by weight, it absorbs ultraviolet rays, causes yellowing of the weather resistant flame retardant resin layer (1) and deterioration of the coating film, resulting in a weather resistance. It tends to decline.

  The weather resistant flame retardant resin layer (1) may contain inorganic fine particles or organic fine particles in order to improve surface slipperiness and blocking properties.

  Specific examples of inorganic fine particles include silica, glass fiber, glass powder, glass beads, clay, wollastonite, iron oxide, antimony oxide, lithopone, pumice powder, aluminum sulfate, zirconium silicate, dolomite, iron sand and the like Particles.

  The inorganic fine particles may contain impurities to such an extent that the characteristics are not impaired. Further, the shape of the particles may be any shape such as powder, granule, granule, true sphere, flat plate, and fiber.

  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, silicone resin, methacrylate resin, acrylate resin and other polymer particles, Alternatively, cellulose powder, nitrocellulose powder, wood powder, waste paper powder, rice husk powder, starch and the like can be mentioned.

  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. The organic particles may contain impurities to the extent that the characteristics are not impaired. The shape of the particles may be any shape such as powder, granule, granule, flat plate, and fiber.

In addition, the weather resistant flame retardant resin layer (1) has various heats other than the weather resistant resin (B) as long as the effects of the present invention are not hindered in order to increase the strength of the obtained weather resistant flame retardant resin layer. A plastic resin may be contained.
Examples of the thermoplastic resin include polypropylene, polyethylene, ethylene-vinyl acetate copolymer, polyisobutylene, polybutadiene, polystyrene, polycarbonate, polymethylpentene, ionomer, acrylonitrile-butadiene-styrene resin, polyvinyl alcohol, polyamide resin, polyacetal, An epoxy resin etc. are mentioned.

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

A pigment may be added to the weather resistant resin layer (1) for the purpose of coloring.
As the pigment, conventionally known pigments can be used, and inorganic pigments such as carbon black, titanium oxide, zinc oxide, lead oxide, zinc sulfide, and lithobon, and various organic pigments can be used.

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

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, olefin films such as polyethylene, polypropylene, and polycyclopentadiene, polyvinyl fluoride, and polyvinylidene fluoride. Fluorine films such as films, polytetrafluoroethylene films, and ethylene-tetrafluoroethylene copolymer films, acrylic films, and triacetyl cellulose films can be used. From the viewpoint of film rigidity and cost, a polyester resin film is preferable, and a polyethylene terephthalate film is preferable.
Further, these films may have a single layer or a multilayer structure of two or more layers.

  These plastic film substrates (2) may be colorless or may contain coloring components such as pigments or dyes. Examples of the method of containing the coloring component include a method of kneading the coloring component in advance at the time of film formation, a method of printing the coloring component on a colorless transparent film substrate, and the like. Further, a colored film and a colorless transparent film may be bonded together.

Next, the easy-adhesive layer (3) used in the present invention will be described.
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), on one side of the solar cell back surface protective sheet. It is a resin layer provided on the outermost surface.
And when forming a solar cell module, non-light-receiving surface side sealing material (IV) and the solar cell back surface protection sheet (V) of this invention are stuck so that an easily adhesive layer (3) may contact | connect. By doing, a solar cell back surface protection sheet is attached to the solar cell module.

  The easy-adhesive layer (3) used in the present invention can be formed from general adhesives containing various resins. Specific examples include polyester resins, urethane resins, and acrylic resins, and these can be used alone or in combination of two or more. Further, a composite of these resins can be used.

  Polyester resins are polyester resins obtained by reacting a carboxylic acid component and a hydroxyl component (esterification reaction, transesterification reaction), a polyester resin having a hydroxyl group, and a polyester polyurethane resin obtained by further reacting with an isocyanate compound, It also includes a polyester polyurethane polyurea resin obtained by reacting a diamine component.

The carboxylic acid component constituting the polyester resin includes benzoic acid, p-tert-butylbenzoic acid, phthalic anhydride, isophthalic acid, terephthalic acid, succinic anhydride, adipic acid, azelaic acid, tetrehydrophthalic anhydride, hexahydro anhydride Examples include phthalic acid, maleic anhydride, fumaric acid, itaconic acid, tetrachlorophthalic anhydride, 1,4-cyclohexanedicarboxylic acid, trimellitic anhydride, methylcyclocentricarboxylic anhydride, pyromellitic anhydride, ε-caprolactone, fatty acid it can.
Examples of the hydroxyl group component constituting the polyester resin include ethylene glycol, propylene glycol, 1,3-butylene glycol, 1,6-hexanediol, diethylene glycol, dipropylene glycol, neopentyl glycol, triethylene glycol, and 3-methylpentanediol. In addition to diol components such as 1,4-cyclohexanedimethanol, polyfunctional alcohols such as glycerin, trimethylolethane, trimethylolpropane, trishydroxymethylaminomethane, pentaerythritol and dipentaerythritol can be exemplified.
According to a conventional method, those obtained by polymerizing these carboxylic acid component and hydroxyl group component into a predetermined polyester resin can be used in the present invention.

The urethane-based resin 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 component include polyethylene glycol, polypropylene glycol, polymer polyols such as polyether polyols added with ethylene oxide or propylene oxide, acrylic polyols, and polybutadiene polyols.
As an isocyanate compound, the thing similar to the polyisocyanate compound (C) mentioned later can be illustrated. Trimethylene diisocyanate (TDI), hexamethylene diisocyanate (HDI), methylene bis (4,1-phenylene) = diisocyanate (MDI), 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate (IPDI), xylylene diisocyanate ( XDI), trimethylolpropane adducts of these diisocyanates, isocyanurates that are trimers of these diisocyanates, burette conjugates of these diisocyanates, polymeric diisocyanates, and the like.

As a monomer constituting the acrylic resin, the general formula (a) CH ₂ = CR ₁ —CO—OR ₂ (R ₁ is a hydrogen atom or a methyl group, R ₂ is a hydroxyl group or a substituent having 1 to 20 carbon atoms). Acrylic acid, methacrylic acid, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-hexyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, 4-hydroxybutyl acrylate, Examples include hydroxypropyl acrylate, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, butyl methacrylate, n-hexyl methacrylate, lauryl methacrylate, 2-hydroxyethyl methacrylate, 4-hydroxybutyl methacrylate, hydroxypropyl methacrylate, etc. it can. Furthermore, acrylamide, methacrylamide, acrylonitrile, methacrylonitrile, N-methylol acrylamide, N-alkylol acrylamide, diacetone acrylamide, diacetone methacrylamide, acrolein, methacrolein, glycidyl methacrylate and the like can be exemplified as reactive monomers. Those obtained by copolymerizing these monomers according to a conventional method to obtain a predetermined acrylic resin can be used in the present invention.

In order to improve the toughness, stretchability, heat resistance, moist heat resistance, and weather resistance of the easy-adhesive layer (3), an adhesive containing a crosslinking agent is used, and the non-light-receiving surface side sealing material (IV) and the present invention are used. When the solar cell back surface protective sheet (V) is stacked and bonded to form a solar cell module, the crosslinker-containing easy-adhesive layer (3) on the outermost surface of the solar cell back surface protective sheet (V) may be cross-linked. preferable.
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 includes a hydroxyl group, a carboxyl group, a sulfonyl group, a phosphonyl group, an isocyanate group, and an epoxy group. It is preferable to have reaction points such as.

  Examples of the crosslinking agent include polyisocyanate compounds, polyglycidyl compounds, and polyaziridyl compounds.

From the viewpoint of durability and coating liquid stability, an isocyanate compound is preferred as the 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. Furthermore, a polyisocyanate compound is preferable from the viewpoint of improving durability. A blocked polyisocyanate compound may also be used.
As a polyisocyanate compound, the thing similar to the polyisocyanate compound illustrated as a crosslinking agent of a weather resistant resin (B) can be used.

  As the crosslinking agent, in addition to the above polyisocyanate compound, a known oxazoline compound such as 2,5-dimethyl-2-oxazoline, 2,2- (1,4-butylene) -bis (2-oxazoline) or hydrazide is used. Compounds such as isophthalic acid dihydrazide, sebacic acid dihydrazide, adipic acid dihydrazide can be included.

  The solar cell back surface protective sheet can include a water vapor barrier layer (4) in order to impart moisture resistance. Examples of the water vapor barrier layer include a metal foil or a vapor deposition layer of a metal oxide or a non-metal inorganic oxide.

As the metal foil, aluminum foil, iron foil, zinc plywood and the like can be used. Among these, from the viewpoint of corrosion resistance, aluminum foil is preferable, and the thickness is preferably 10 μm to 100 μm, and more preferably. Is preferably 20 μm to 50 μm.
Conventionally known various adhesives can be used for the lamination of the two.

The vapor deposition layer is provided on one surface of the plastic film (2). What laminated | stacked single-sided vapor deposition polyester films via an interlayer adhesive layer, or what laminated | stacked single-side vapor deposition polyester film and another vapor deposition film via an interlayer adhesive layer can also be used.
Examples of the metal oxide or non-metal inorganic oxide to be deposited include oxides such as silicon, aluminum, magnesium, calcium, potassium, tin, sodium, boron, titanium, lead, zirconium, and yttrium. Alkali metal and alkaline earth metal fluorides can also be used, and these can be used alone or in combination.
These metal oxides or non-metal inorganic oxides can be deposited using a conventionally known PVD method such as vacuum deposition, ion plating, sputtering, or the like, or a CVD method such as plasma CVD or microwave CVD.

  The water vapor barrier layer (4) may be a laminate in which two or more of the above barrier layers are laminated in accordance with required electrical insulation properties and water vapor barrier properties.

  As 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 (4), a roll knife coater, a die coater, a roll coater, a bar coater, A weather-resistant flame retardant resin composition (1 ′) or an easy-adhesive composition (3) by a conventionally known coating method such as a gravure roll coater, reverse roll coater, dipping, blade coater, gravure coater, micro gravure coater, comma coater, etc. And a film formed from a weather-resistant flame retardant resin composition (1 ') or an easy-adhesive composition (3'), such as dry lamination, extrusion lamination, and thermal lamination. Laminated plastic film (2) or water vapor And a method of attaching a rear layer (4).

The manufacturing method of the solar cell back surface protection sheet of this invention is demonstrated.
The solar cell back surface protective sheet of the present invention comprises a weather-resistant flame retardant resin layer (1), a plastic film (2), and an easy-adhesive layer (3). The weather resistant flame retardant resin layer (1) constitutes, and the other surface of the solar cell back surface protective sheet constitutes the easy adhesive layer (3).
FIG. 2 (a) shows still another aspect of the solar cell back surface protective 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. It is a typical sectional view shown.
The solar cell back surface protective sheet of the present invention can further include a water vapor barrier layer (4), an interlayer adhesive layer (5), and the like.
For example, FIG. 2B shows 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). It is typical sectional drawing which shows another aspect of the solar cell back surface protection sheet of this invention which becomes.
FIG. 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). It is typical sectional drawing which shows another aspect of the solar cell back surface protection sheet of this invention which becomes.

Next, the manufacturing method of the solar cell module of this invention is demonstrated.
The solar cell module of the present invention includes a solar cell surface sealing sheet (I) positioned on the light receiving surface side of the solar cell, a sealing material layer (II) positioned on the light receiving surface side of the solar cell, and a solar cell element (III ), The sealing material layer (IV) positioned on the non-light-receiving surface side of the solar cell, and the solar cell back surface protective sheet of the present invention described in detail as essential constituent layers, and the solar cell back surface protective sheet of the present invention It can obtain by laminating | stacking so that the weather-resistant flame-retardant resin layer (1) to be located farthest from the said solar cell surface sealing sheet (I). In other words, the solar cell back surface sealing sheet is laminated so that the non-light-receiving surface side sealing material layer (IV) is in contact with the easy-adhesive layer (3) constituting the solar cell back surface protection sheet of the present invention. Thus, the solar cell module of the present invention can be obtained. When the non-light-receiving surface side sealing material layer (IV) and the solar cell back surface protective sheet are laminated, they may be brought into contact with each other under reduced pressure and then superposed under heating and pressure. In the case where the easy-adhesive layer (3) is thermosetting, after returning to normal pressure, the easy-adhesive layer (3) can be further cured by placing it under high temperature conditions.

Hereinafter, the present invention will be described in more detail with reference to examples. In the examples, “part” means “part by weight” and “%” means “% by weight”.
In the table, each symbol is as follows.
Phosphorus flame retardant A1: Exolit OP935 (aluminum trisdiethylphosphinate, manufactured by Clariant)
Phosphorus flame retardant A2: Exolit OP1230 (aluminum trisdiethylphosphinate, manufactured by Clariant)
Phosphorus flame retardant A3: Exolit OP1312 (mixture of aluminum trisdiethylphosphinate and melamine phosphate, manufactured by Clariant)
Phosphorus flame retardant A4: SPB-100 (phenoxycyclotriphosphazene, manufactured by Otsuka Chemical)
Phosphorus flame retardant A5: SPH-100 (4-hydroxyphenoxycyclotriphosphazene, manufactured by Otsuka Chemical)
Phosphorus flame retardant A6: FP-300 (4-cyanophenoxycyclotriphosphazene, Fushimi Pharmaceutical)
Phosphorus flame retardant A7: Phosmel 100 (melamine phosphate, manufactured by Hitachi Chemical)
Phosphorus flame retardant A8: Phosmel 200 (melamine phosphate dimer, manufactured by Hitachi Chemical)
Phosphorus flame retardant A9: ammonium polyphosphate Phosphorus flame retardant A10: triphenyl phosphate (manufactured by Daihachi Chemical Industry)
Non-phosphorous flame retardant A11: STABIACE MC-55 (melamine cyanurate, manufactured by Sakai Chemical Industry)
Non-phosphorous flame retardant A12: Aluminum hydroxide Halogen flame retardant A13: Fire cut FCP-83D (decabromodiphenyl oxide, manufactured by Suzuhiro Chemical)
Fluorine resin B1: PVDF emulsion solution (manufactured by Arkema)
Fluorine resin B2: PVDF pellet (manufactured by Arkema, KYNAR)
Urethane resin B3: Urethane resin solution (Sanpuren, Sanyo Chemical)
Polyester resin B4: Polyester resin pellet (Toyobo, Byron)
Acrylic resin B5: Benzotriazole and hydroxyl group-containing acrylic resin (manufactured by Nippon Shokubai Hals Hybrid UV-G720T solution, hydroxyl value = 38)
Taipei CR-97: Titanium oxide for white pigments manufactured by Ishihara Sangyo

<Adjustment of weather resistant flame retardant resin solution and weather resistant flame retardant film (1-14, 23, 25-31)>
Phosphorus flame retardant (A), weather resistant resin (B), and pigment (C) are mixed in the solid content composition ratio shown in Table 1, and the solid content is 50% in a 50/50 mixed solvent of toluene / ethyl acetate. So that it was dissolved. Furthermore, after disperse | distributing with the paint shaker, the weather-resistant flame retardant resin solution (1-14, 23-31) was obtained.
The above weather-resistant flame retardant resin solution (1-14, 23-31) is applied to an exfoliated polyethylene terephthalate (hereinafter referred to as Sepa PET) with an applicator, and the solvent is stripped off to create a 30 μm coating film. A weather-resistant flame retardant film was prepared by peeling from PET.

<Adjustment of weather-resistant flame retardant film (15-22, 32, 34-39)>
After mixing a phosphorus flame retardant (A), a weather resistant resin (B), and a pigment (C) in the composition shown in Table 1, and premixing them using a tumbler (SKS50, manufactured by Shinei Koki Sangyo Co., Ltd.), biaxial After kneading and extruding using an extruder (manufactured by Nippon Placon Co., Ltd.), it was cut with a pelletizer to obtain a pellet-shaped resin composition. The resin composition thus obtained was extruded into a sheet using a T-die extruder, and a weather resistant flame retardant film having a thickness of 30 μm was prepared.

<Flammability measurement: UL test>
A weather resistant flame retardant film (1 to 39) having a thickness of 30 μm was evaluated according to the HB standard or V standard defined in UL94.
<< HB Standard >> This is a test in which a strip-shaped test piece is placed horizontally, burned by applying a burner flame to one end, and a pass / fail judgment is made at the rate at which the combustion proceeds. In the case of a weather-resistant flame retardant film having a thickness of 30 μm, a burning rate of 40 mm / min or less or 75 mm / min or less is regarded as “pass” for the HB test.
<< V standard >> Five test pieces are used. A burner flame is applied to the lower end of the strip-shaped test piece supported vertically and held for 10 seconds. Then, the burner flame is released from the test piece. When the flame disappears, the burner flame is applied for another 10 seconds and then the burner flame is released.
The flaming combustion duration after the first and second flame contact, the flaming combustion duration and the non-flame burning duration after the second flame contact, and the flammable combustion time of the five test pieces Judgment is based on the total and the presence or absence of combustion drops (drip). In particular,
V-0: There is no burning fallen object (drip), the flaming combustion duration after the end of flame contact is within 10 seconds in both the first and second times, and the second flaming combustion duration and flameless combustion time Within 30 seconds. Furthermore, the total flammable burning time of 5 test pieces is within 50 seconds.
V-1: There is no burning fallen object (drip), and the first and second flame-retardant durations after flame contact are within 30 seconds, and the second flame-retardant duration and flame-free duration Within 60 seconds. In addition, the total flame burning time of the five test pieces is within 250 seconds.
V-2: Same as V-1, except that there are burning fallen objects (drip).
Since the HB standard and the V standard are different standards, direct comparison is not possible. However, the V standard is more strict than the HB standard, and even if it passes the HB standard, the V standard V- Sometimes less than 2 levels. Therefore, the order of good or bad flame retardancy is better as shown on the left.
>V-0>V-1>V-2> HB pass> HB fail The result is shown in Table 2.

<Creation of solar cell back surface protection sheet 1>
Corona treatment was applied to both sides of a polyester film (Teijin Limited, Tetoron S, thickness 188 μm, hereinafter referred to as “transparent substrate A”), and polyester adhesive “Dyna Leo VA-3020 / HD-701” (Toyo) on one side Ink Holdings Co., Ltd., blending ratio 100/7, the same applies below) was applied with a gravure coater, the solvent was dried, and an interlayer adhesive layer of 10 g / square meter was provided. Vapor deposition PET (Mitsubishi Resin Co., Ltd., Tech Barrier LX, thickness 12 μm) was superposed. Thereafter, an aging treatment was performed at 50 ° C. for 4 days to cure the interlayer adhesive layer, and a polyester film-deposited PET laminate was prepared.
In addition, the vapor deposition PET used is vapor deposition PET which produced the silica by vacuum vapor deposition.

  Then, the weather resistant flame retardant resin solution 1 described in Table 1 is applied to the polyester film surface of the polyester film-deposited PET laminate, the solvent is dried, and a weather resistant flame retardant resin layer having a film thickness of about 15 μm is formed. Provided. Thereafter, aging treatment was performed at 40 ° C. for 3 days to cure the weather resistant flame retardant resin layer, and a weather resistant flame retardant resin layer-polyester film-deposited PET laminate was prepared.

  Finally, a polyester adhesive “Dyna Leo VA-3020 / HD-701” is applied to the vapor-deposited PET surface of the weather-resistant flame-retardant resin layer-polyester film-deposited PET laminate with a gravure coater, and the solvent is dried. An easy-adhesive layer of 5 g / square meter (film thickness: 5 μm) was provided to prepare a solar cell back surface protective sheet 1.

<Creation of Solar Cell Back Surface Protection Sheets 2-14, 23-31>
In the same manner as the solar cell back surface protective sheet 1, the solar cell back surface protective sheets 2 to 14 and 23 to 23 are used by using the weather resistant flame retardant resin solutions 2 to 14 and 23 to 31 shown in Table 1-1 and Table 1-2. 31 was created.

<Creation of solar cell back surface protection sheet 15>
In the same manner as in the case of the solar cell back surface protective sheet 1, a polyester film-deposited PET laminate was first prepared.

  Next, a polyester adhesive “Dyna Leo VA-3020 / HD-701” is applied to the polyester film surface of the polyester film-deposited PET laminate by a gravure coater, the solvent is dried, and the coating amount is 10 g / square meter. A layer was provided, and a weather-resistant flame retardant film (film thickness: 30 μm) described in Table 2 was superposed on the interlayer adhesive layer. Thereafter, aging treatment was performed at 50 ° C. for 4 days to cure the weather resistant flame retardant resin layer, and a weather resistant flame retardant resin layer-polyester film-deposited PET laminate was prepared.

  Finally, a polyester adhesive “Dyna Leo VA-3020 / HD-701” is applied to the vapor-deposited PET surface of the weather-resistant flame-retardant resin layer-polyester film-deposited PET laminate with a gravure coater, and the solvent is dried. An easy-adhesive layer of 5 g / square meter (film thickness: 5 μm) was provided to create a solar cell back surface protective sheet 15.

<Creation of Solar Cell Back Surface Protection Sheets 16-22, 32-39>
In the same manner as the solar cell back surface protection sheet 15, the solar cell back surface protection sheets 16 to 22 and 32 to 39 are used by using the weather-resistant flame retardant films 16 to 22 and 32 to 39 shown in Table 1-1 and Table 1-2. It was created.

<Creation of solar cell back surface protection sheet 40>
A weather-resistant flame retardant resin layer having the same composition and the same composition as that of the weather-resistant flame retardant film 15 and a film thickness of 5 μm is prepared. A solar cell back surface protective sheet 40 having a layer structure of polyester film-deposited PET-adhesive layer was prepared.

<Creation of solar cell back surface protection sheet 41>
A solar cell back surface protective sheet 41 having a layer structure of polyester film-deposited PET-adhesive layer was prepared by the same production method as that of the solar cell back surface protective sheet 15 except that a weather-resistant flame retardant resin layer was not provided. .

[Example 1]
Using the solar cell back surface protective sheet 1, cross-cut adhesion, combustibility, moist heat resistance, and weather resistance were evaluated by the methods described below.

<Cross-cut adhesion measurement>
For cross-cut adhesion, the weather-resistant flame retardant resin layer of the solar cell back surface protective sheet 1 is scratched in a cross shape with a cutter, subjected to a cellophane tape peeling test, and the state of the remaining coating film after the cellophane tape peeling is visually observed. Then, the adhesion of the weather resistant flame retardant resin layer to the polyester film was evaluated.
○: The peripheral part of the wound is not peeled off.
(Triangle | delta): The tendency of peeling a little is seen in the peripheral part of a crack | wound.
X: Clear peeling is seen around the wound.

<Flammability measurement: Radiant panel (RP) test>
The combustibility was determined by performing a flame propagation test (radiant panel test) in accordance with ASTM-E162, calculating the flame diffusion coefficient from the combustion speed and the heat release coefficient from the combustion temperature, and taking the product as the flame propagation index.
In the flame propagation test, in the presence of a radiant panel at 600 ° C, the solar cell back surface protection sheet is ignited, the flame diffusion coefficient is determined from the burning speed of the solar cell back surface protection sheet, and the heat release coefficient is determined from the combustion temperature. This is an evaluation method for calculating an index.
The standard value of UL1703 is 100 or less, and if it exceeds 100, it will be rejected.
○ : Less than 50
Δ : 50 or more and less than 100 ×: 100 or more and less than 150 XX: 150 or more

<Moisture and heat resistance test>
Humidity and heat resistance is measured by cross-cut adhesion and yellowing after standing for 96 hours, 192 hours and 288 hours under the conditions of temperature 105 ° C, relative humidity 100% RH and 2 atm using a pressure cooker tester. did.
Cross-cut adhesion was evaluated by the same method and standard as described above.
The yellowing degree is measured from the weather-resistant flame retardant resin layer side of the solar cell back surface protective sheet 1 using a color difference meter CR-300 (manufactured by Konica Minolta) according to the method described in JIS-Z8722, and L ^* a ^* b ^* Evaluated by Δb value when expressed in a color system.
○: Less than Δb value 2 Δ: Δb value 2 or more and less than 4 ×: Δb value 4 or more XX: Δb value 10 or more

<Weather resistance test>
The weather resistance was evaluated using an eye super UV tester (manufactured by Iwasaki Electric Co., Ltd.) under the following conditions in terms of cross-cut adhesion, yellowing degree, and film loss after 10 cycles (that is, after 120 hours).
(Weather resistance test conditions)
1) 63 ° C 70% 90mW / cm2 irradiation 4h
2) 70 ° C 90% standing 4h
3) Shower 10 seconds → condensation 4h → shower 10 seconds
4) The above 1), 2) and 3) are repeated 10 cycles (1 cycle, 12 hours. 10 cycles for a total of 120 hours.)
[Film reduction] A part of the surface of the weather-resistant flame retardant resin layer of each test piece was protected with a weather-resistant tape, and the level difference between the protected part and the unprotected part after 10 cycles was measured and evaluated according to the following criteria: did.
○: Film reduction is less than 1 μm Δ: Film reduction is from 1 μm to less than 5 μm ×: Film reduction is from 5 μm to less than 10 μm XX: Film reduction is from 10 μm or more

[Examples 2 to 14], [Comparative Examples 1 to 9]
In the same manner as in Example 1, the solar cell back surface protective sheets 2 to 14 and 23 to 31 were used to evaluate cross-cut adhesion, combustibility, moist heat resistance, and weather resistance. The above results are shown in Table 3.

[Example 15]
Using the solar cell back surface protective sheet 15, evaluation of combustibility, moist heat resistance and weather resistance was performed in the same manner as in Example 1. In addition, since the solar cell back surface protection sheet 15 using a weather-resistant flame-retardant film cannot evaluate crosscut adhesiveness, the toughness of a weather-resistant resin layer was evaluated by the method mentioned later instead.

<Toughness measurement>
The solar cell back surface protection sheet 15 was cut into a 15 mm wide rectangle to obtain a test piece. Each test piece was subjected to a T-peeling test between a weather resistant flame retardant resin layer (ie, weather resistant flame retardant film) and a polyester film at a load speed of 100 mm / min using a tensile tester. Evaluation was performed based on the load when the flame-retardant flame retardant film breaks.
◯: 3 N / 15 mm or more Δ: 0.5 N / 15 mm or more to less than 3 N / 15 mm ×: Less than 0.5 N / 15 mm XX: The weather resistant resin layer (1) becomes brittle and cannot be evaluated.

[Examples 16 to 22], [Comparative Example 10-19]
In the same manner as in Example 15, the solar cell back surface protection sheets 16-22 and 32-41 were used to evaluate the toughness, moist heat resistance and weather resistance of the weather resistant flame retardant resin layer and the flammability of the solar cell back surface protection sheet. went. The results are shown in Table 4.

As shown in Tables 3 and 4, Examples 1 to 22 (when using weather resistant flame retardant resin solutions 1 to 14 or weather resistant flame retardant resin films 15 to 22) are flammability tests by flame propagation tests. But it shows excellent flame retardancy. In addition, it exhibits excellent adhesion before and after the moist heat resistance test and the weather resistance test, and hardly undergoes yellowing even after the moist heat resistance test and the weather resistance test, and the thickness of the coating film and film hardly decreases even after the weather resistance test. That is, the back surface protection sheet for solar cells of Examples 1 to 22 is a satisfactory back surface protection sheet for solar cells.
In particular, in Examples 1-3, 5-8, and 15-16 using aluminum phosphinate or phosphazene, the hydrophobicity of the weather-resistant flame retardant resin layer (1) is increased, so that the phosphorus flame retardant (A) is completely absent. A remarkable improvement in wet heat resistance is observed as compared with Comparative Examples 1 to 3 and 10 to 12 in which the weather resistant flame retardant resin solutions 23 to 25 or the weather resistant flame retardant films 32 to 34 are used.
In addition, as Table 2 shows, Examples 1-22 show the result excellent also in the flame retardance test defined by UL-94.

On the other hand, Comparative Examples 1 to 3 and 10 to 12 do not have a phosphorus-based flame retardant and thus have poor flame retardancy and do not satisfy UL 1703 standards. In particular, Comparative Example 1 and Comparative Example 10 (using the weather resistant flame retardant resin solution 23 or the weather resistant flame retardant film 32) are general flame retardant properties as shown in Table 2 in the case of the weather resistant flame retardant film alone. In the UL94 test, which is an indicator of the above, a V-0 result is exhibited and no combustion occurs.
However, the weather resistant flame retardant film does not have a function of suppressing the flammability of the plastic film (2) which is another layer constituting the back protective sheet for solar cells, that is, the polyester film in the comparative example. There is no effect. As a result, as shown in Tables 3 and 4, when the flammability as a solar cell back surface protective sheet is evaluated in the flame propagation test defined in ASTM E162, the standard of UL-1703 is not satisfied.

Comparative Examples 4, 6, and 14 (using the weather-resistant flame retardant resin solutions 26 and 28 or the weather-resistant flame retardant film 36) were prepared by using ammonium polyphosphate as a phosphorus-based flame retardant, and Comparative Examples 5, 13, and 15 (weather resistance). The flame retardant resin solution 27 or the weather resistant flame retardant resin films 35 and 37) use triphenyl phosphate as the phosphorus flame retardant, respectively. Therefore, in the flammability evaluation by the flame propagation test, the flame retardant effect is It can be seen.
However, significant degradation is seen in the wet heat test. That is, phosphoric acid, which is a strong acid generated by hydrolysis of ammonium polyphosphate and triphenyl phosphate during the wet heat test, deteriorates and embrittles the weather-resistant flame retardant resin layer (1) and the plastic film (2). .

Comparative Examples 7, 8, and 16 (using the weather-resistant flame retardant resin solution 29, 30 or the weather-resistant flame retardant film 38) use melamine cyanurate or aluminum hydroxide as a flame retardant, and are resistant to weather and moisture. There is no big problem with heat.
However, unlike phosphorus-based flame retardants that form a carbonized film to exhibit flame retardancy, melamine cyanurate and aluminum hydroxide do not form a carbonized film, and thus the flame-retardant effect is insufficient. In addition, when the blending amount of these flame retardants is increased to improve flame retardancy, the weather resistant resin (1) is relatively reduced, making it difficult to produce the weather resistant flame retardant resin layer (1) itself, and weather resistance. It can be predicted that it will have a significant effect on the heat resistance and wet heat resistance.

  In addition, since Comparative Example 9 (using the weather resistant flame retardant resin solution 31) contains benzotriazole as the weather resistant resin (B) and uses an acrylic resin having a hydroxyl value of 38, the weather resistance is excellent. In addition, since phosphinates with excellent flame retardancy are used, the initial properties are excellent. However, after the heat and humidity test, the plastic film (2) is flaked and peeled, so the phosphinate has excellent moisture and heat resistance. Even if is used, the weather-resistant flame-retardant resin layer (1) peels off, and the flame retardancy after the wet heat test cannot be maintained.

  Further, Comparative Example 17 (using weather resistant flame retardant film 39) uses decabromodiphenyl ether which is a halogenated flame retardant as a flame retardant, and there is no major problem with flame retardant. However, since it yellows significantly after a weather resistance test or a wet heat test, it is unsuitable for use as a member of a solar cell module that is constantly exposed to light or wet heat.

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

  Comparative Example 19 (using the weather resistant flame retardant resin film 41) does not have the weather resistant flame retardant resin layer (1), so that the plastic film (2) is exposed on the surface and the weather resistance is significantly inferior, The flammability is also bad.

  In addition, since Example 9 (uses a weather-resistant flame retardant resin solution 9) has a low total phosphorus concentration, it is slightly inferior in flame retardancy in a flame propagation test. Examples 10 and 18 (weather-resistant flame retardant resin solution 10 Or using a weather-resistant flame retardant film 18), the amount of phosphorus-based flame retardant (A) added is large, and the total amount of the weather-resistant resin (B) is relatively reduced. It is done.

Moreover, Examples 11-14 (we use a weather-resistant flame-retardant resin solution 11-14) use urethane type resin as a weather-resistant resin (B), Examples 19-22 (use a weather-resistant flame-retardant resin film 19-22) ) Uses a polyester-based resin, and is slightly inferior in heat-and-moisture resistance and weather resistance than when a fluorine-based resin is used.
However, Examples 11, 12, 19, and 20 using aluminum phosphinate and phosphazene increase the hydrophobicity of the weather-resistant flame-retardant resin layer (1), and therefore, Examples 13 using melamine phosphate in heat and moisture resistance. , 14, 21 and 22.

(I): Solar cell surface sealing sheet positioned on the light receiving surface side of the solar cell (II): Sealing material layer positioned on the light receiving surface side of the solar cell (III): Solar cell (IV): Solar cell Sealant layer located on the non-light-receiving surface side (V): Solar cell back surface protective 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 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 easy adhesive layer (3),
The weather resistant flame retardant resin layer (1) constitutes one surface of the solar cell back surface protective sheet, and the easy adhesive layer (3) constitutes the other surface of the solar cell back surface protective sheet,
A phosphorus-based flame retardant (A) selected from the group consisting of a phosphazene compound, a phosphinic acid compound, and a (poly) melamine phosphate, a fluorine-based resin, a urethane-based resin, and a polyester. Containing a weather resistant resin (B) selected from the group consisting of resin
Thickness t of the weather-resistant flame-retardant resin layer (1) is Ri from 2.5 to 20% der of the total thickness of the solar battery backside protection sheet,
The solar cell back surface protection sheet characterized by the total phosphorus concentration derived from the said phosphorus flame retardant (A) in the said weather-resistant flame-retardant resin layer (1) being 2.1 to 14.2 weight% .   The solar cell back surface protective sheet according to claim 1, 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 derived from the phosphorus flame retardant (A) in the weather resistant flame retardant resin layer (1) is 3 to 10 wt%.   The solar cell back surface protective sheet according to any one of claims 1 to 3, wherein the weather-resistant resin (B) is a fluororesin. Solar cell surface sealing sheet (I) positioned on the light receiving surface side of the solar cell, sealing material layer (II) positioned on the light receiving surface side of the solar cell, solar cell (III), non-light receiving surface side of the solar cell The solar cell back surface protective sheet (V) according to any one of claims 1 to 4, wherein the solar cell back surface protective sheet (V) is in contact with the sealant layer (IV) positioned at the surface and the non-light-receiving surface side sealant layer (IV). A solar cell module comprising:
The solar cell module, 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).

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