JP5211576B2 - Solar cell back surface sealing sheet and solar cell module using the same - Google Patents

Description

  The present invention relates to a solar cell back surface sealing sheet, and more specifically, heat and moisture resistance without appearance defects and gas barrier performance deterioration due to poor adhesion even in severe storage environments under high temperature and high humidity required for solar cells. The present invention relates to a solar cell back surface sealing sheet having excellent adhesion, and a solar cell module using the solar cell back surface sealing sheet.

  In recent years, various efforts have been made to suppress carbon dioxide emissions while interest from various countries both inside and outside Japan has increased. Increasing fossil fuel consumption leads to an increase in atmospheric carbon dioxide, and the greenhouse effect raises the Earth's temperature, significantly affecting the global environment. Various studies have been carried out to solve this global problem, and in particular, solar power generation is highly expected in terms of cleanliness and non-pollution.

  A solar cell constitutes the heart of a photovoltaic power generation system that directly converts sunlight energy into electricity, and is made of a single crystal, polycrystalline, or amorphous silicon semiconductor. As the structure of the solar cell, a single solar cell element (cell) is not used as it is, and generally several to several tens of solar cell elements are wired in series and in parallel for a long time (about In order to protect the cell over 20 years, various packaging has been performed and unitized. The unit incorporated in this package is called a “solar cell module”.

  In general, a solar cell module covers the surface exposed to sunlight with a glass surface, fills the gap with a filler made of a thermoplastic (especially ethylene-vinyl acetate copolymer), and protects the back surface with a sealing sheet. It has been configured.

  By the way, since a solar cell module is mainly used outdoors, sufficient durability and weather resistance are required in its configuration and material structure. In order to meet these requirements, as an approach from the substrate side, fluorine with excellent weather resistance and flame retardancy, and ethylene-vinyl acetate copolymer that is often used as a filler for solar cell modules and good adhesion A resin using a resin has been proposed (see, for example, Patent Documents 1 and 2). In addition, a sheet for sealing a back surface of a solar cell using a polyester film such as polyethylene terephthalate having excellent electrical insulation has been developed. Furthermore, in order to improve the weather resistance mentioned as a demerit using a polyester film, those blended with an ultraviolet absorber (for example, see Patent Document 3), and those that define the amount of cyclic oligomer in the polyester (for example, Patent Documents 4, 5, etc.), and those that define the molecular weight of polyester (for example, see Patent Document 6, etc.) have been proposed.

  Further, the solar cell back surface sealing sheet is required to have not only the above-mentioned substrate strength physical properties but also a low water vapor permeability (excellent moisture barrier property). This is because the module output itself may be affected when the filler is peeled off, discolored, or the wiring is corroded due to moisture permeation. As a countermeasure, for example, as described in Patent Documents 3 to 6 and the like, it has been studied to laminate a gas barrier film on which an inorganic compound is deposited together with a substrate having the above weather resistance.

  Originally, the development background of gas barrier films has the same gas barrier properties as metal foils such as aluminum foil that have been used up to now, and further meets the needs for content visibility, disposal, and use of metal detectors. Therefore, for example, as described in Patent Documents 7 and 8 below, inorganic oxides such as silicon oxide, aluminum oxide, and magnesium oxide are deposited on a thermoplastic resin film by a forming means such as a vacuum deposition method or a sputtering method. It begins with the formation of the film. And, the packaging material obtained using this gas barrier film is improved in that it prevents deterioration of gas barrier properties due to temperature and water (humidity) such as boil sterilization, retort sterilization, and autoclave sterilization, and does not involve delamination etc. Have been studied by taking the measures described in Patent Documents 9 and 10, for example. The gas barrier film used in the solar cell back sheet described above has also been studied by using the techniques described in Patent Documents 7 to 10.

  Since the solar cell module needs to be guaranteed for 20 to 30 years as described above, the product performance is evaluated by storage and evaluation under severe conditions. This severe condition is carried out by storing for 2000 to 3000 hours at 85 ° C.-85% relative humidity, and has been studied by conducting an accelerated test on the weather resistance and gas barrier performance of the substrate in this environment. .

On the other hand, since the evaluation time of 2000 to 3000 hours is required even in the above severe conditions, further accelerated evaluation under severe conditions is required, and 105 ° C.-100% relative humidity in PCT evaluation (accelerated test with pressurized steam). The evaluation form of 200 hours has come to be performed below. However, in the case of this PCT evaluation, since the storage evaluation environment is too harsh, the solar cell back surface sealing sheet has a result of appearance failure accompanying delamination. In addition, the problem of delamination in the gas barrier substrate (GS) may affect not only the appearance failure of the solar cell back surface sealing sheet, but also the performance of the solar cell due to a decrease in gas barrier performance. is there.
Special table hei -500214 gazette Japanese translation of PCT publication No. 2002-520820 JP 2001-1111073 A Japanese Patent Laid-Open No. 2002-100788 JP 2002-134771 A JP 2002-26354 A U.S. Pat. No. 3,442,686 Japanese Patent Publication No.63-28017 Japanese Patent No. 3736130 International Publication No. 04/48081 Pamphlet

  The present invention has been proposed in view of such a conventional situation, and even under severe storage conditions under high temperature and high humidity, a poor appearance of a sheet due to poor adhesion between gas barrier substrates (GS), a gas barrier, and the like. An object of the present invention is to provide a solar cell back surface sealing sheet excellent in moisture and heat resistance adhesion without causing performance degradation due to performance degradation, and a solar cell module using the same.

The gist of the present invention aimed at solving the above problems is as follows.
[1] A solar cell back surface sealing sheet having a structure in which at least a weather resistant substrate (DS) and a gas barrier substrate (GS) are laminated,
The gas barrier base material (GS) is Ri Do a laminate comprising plus plastic film layer and the (S) a soft deposition primer layer (P) and a hard deposited primer layer (H) and deposited layer and (V),
The soft deposition primer layer (P) is composed of a compound containing at least the following components (P1), (P2) and (P3):
The primer layer for hard vapor deposition (H) is composed of a compound containing at least the following component (H1) and one or both of (H2) and (H3):
The mass ratio (P1) / (P3) is in the range of 99/1 to 50/50, and the mass ratio {(P1) + (P3)} / (P2) is in the range of 100/5 to 100/100. A sheet for sealing the back surface of a solar cell.
(P1): Amorphous polyester polyol having a glass transition temperature of less than 40 ° C., an isocyanate extension product thereof, or a mixture thereof.
(P2): at least one crosslinking agent selected from an isocyanate compound, a carbodiimide compound, a transition metal compound represented by the general formula M (OR ′) _n , and a phosphorus compound [wherein R ′ is an alkyl group M is a metal ion and n is the valence of the ion. ].
(P3): a polyol that is incompatible with (P1) and has a glass transition temperature of 40 ° C. or higher, an isocyanate extension of this polyol, or a mixture thereof.
(H1): Polyester polyol having a glass transition temperature of 40 ° C. or higher, an isocyanate extension product thereof, an acrylic polyol or an isocyanate extension product thereof, a carbonate polyol or an isocyanate extension product thereof, or a mixture thereof (note that an acrylic polyol or a carbonate polyol is used) When used, (P3) and (H1) may be the same).
(H2): at least one cross-linking agent selected from an isocyanate compound, a carbodiimide compound, a transition metal compound represented by the general formula M (OR ′) _n , and a phosphorus compound [where R ′ is an alkyl group M is a metal ion and n is the valence of the ion. ].
(H3): Organosilane represented by the general formula R—Si (OR ′) ₃ or a hydrolyzate thereof, one or more metal alkoxides represented by the general formula M (OR ′) n or a hydrolyzate thereof, Or a mixture thereof [wherein R is a functional group selected from an alkyl group, a (meth) acryloyl group, a vinyl group, an amino group, an epoxy group, and an isocyanate group, R ′ is an alkyl group, and M is a metal ion. And n is the valence of the ion. ].
[2] The solar cell back surface sealing sheet according to [1] , wherein the polyol of (P3) comprises an acrylic polyol, a carbonate polyol, or a mixture thereof.
[3] the deposition layer (V), silicon oxide having a thickness of 5 to 300 nm, aluminum oxide, said characterized in that it consists of at least one or more inorganic oxides selected from magnesium oxide (1) or [2] The solar cell back surface sealing sheet according to [2] .
[4] The gas barrier substrate (GS) further includes an overcoat layer (O) for vapor deposition laminated on the vapor deposition layer (V),
The solar cell according to any one of [1] to [ 3 ], wherein the deposition overcoat layer (O) is made of a compound containing the following components (O1) and (O2): Sheet for backside sealing.
(O1): Water-soluble polymer.
(O2): an organosilane represented by the general formula R—Si (OR ′) ₃ or a hydrolyzate thereof, one or more metal alkoxides represented by the general formula M (OR ′) _n or a hydrolyzate thereof, Phosphorus compounds, or a mixture thereof [wherein R is a functional group selected from an alkyl group, a (meth) acryloyl group, a vinyl group, an amino group, an epoxy group, an isocyanate group, R ′ is an alkyl group, etc. M is a metal ion, and n is the valence of the ion. ].
[5] A solar cell module using the solar cell back surface sealing sheet according to any one of [1] to [ 4 ].

  As described above, according to the solar cell back surface sealing sheet according to the present invention, since the gas barrier base material (GS) having excellent moisture and heat resistance is used, it has been a problem in the prior art under high temperature and high humidity. It is possible to improve the problem of delamination in storage evaluation, and not only to improve the appearance defect of this solar cell back surface sealing sheet, but also to suppress the performance degradation of the solar cell module. .

  Hereinafter, a solar cell back surface sealing sheet to which the present invention is applied and a solar cell module using the same will be described in detail with reference to the drawings. In addition, in the drawings used in the following description, in order to make the features easy to understand, there are cases where the portions that become the features are enlarged for convenience, and the dimensional ratios of the respective components are the same as the actual ones. Not exclusively.

<Solar cell backside sealing sheet>
First, the solar cell back surface sealing sheet to which the present invention is applied will be described.
The solar cell back surface sealing sheet to which the present invention is applied is, for example, at least a weather-resistant substrate (DS) and a gas barrier, as in solar cell back surface sealing sheets 1A and 1B shown in FIGS. A laminate having a structure in which a base material (GS) is laminated, wherein the gas barrier base material (GS) includes a plastic film layer (S), a soft deposition primer layer (P), and a deposition layer (V); Or it consists of a laminated body containing a plastic film layer (S), a soft deposition primer layer (P), a hard deposition primer layer (H), and a deposition layer (V).

  The inventors of the present invention described the above-described gas barrier substrate, that is, “plastic film layer (S) / deposition layer (V)” or “plastic film layer (S) / primer layer for hard deposition (H) / deposition layer. As a result of investigating and analyzing the cause of delamination that occurs when the gas barrier substrate consisting of (V) "is stored under the above-mentioned 85 ° C.-85% relative humidity, or when PCT evaluation is performed, Peeling occurs between the film layer (S) and the vapor deposition layer (V) or between the plastic film layer (S) and the hard vapor deposition primer layer (H) provided to improve vapor deposition adhesion. It was confirmed.

  The main cause of this is the vicinity of the interface due to the difference in thermal shrinkage between the plastic film layer (S) and the vapor deposition layer (V) or the primer layer (H) for vapor deposition during storage at high temperatures for a long time. And the strain (stress) generated at the interface between the plastic film layer (S) and the vapor deposition layer (V) or the hard deposition primer layer (H). Usually, when designing a laminate having heat resistance, it is used as a publicly known technique to use a material having a high glass transition temperature or a material having a high degree of crystallinity. It was confirmed that it was difficult to adapt with respect to the moisture and heat resistance of the adhesive.

  Next, since it is difficult for the present inventors to use the above technique, as a result of diligent investigation on the improvement measures, the material has no heat resistance, but the shrinkage rate due to heat is small and crystallization occurs. Gas barrier group capable of maintaining not only adhesion but also gas barrier performance even in storage evaluation under the above-mentioned severe environment by using a material that has a small distortion accompanying it and can provide a sticky adhesion mechanism A material (GS) was found.

That is, the gas barrier substrate (GS) used in the present invention is provided with a primer layer (P) for soft vapor deposition formed of a compound containing at least the following components (P1) and (P2) on the plastic film layer (S). It is characterized by that.
(P1): Polyester polyol having a glass transition temperature of less than 40 ° C., an isocyanate extension product thereof, or a mixture thereof.
(P2): at least one crosslinking agent selected from an isocyanate compound, a carbodiimide compound, a transition metal compound represented by the general formula M (OR ′) _n , and a phosphorus compound [wherein R ′ is an alkyl group M is a metal ion and n is the valence of the ion. ].
Hereinafter, the configuration of each layer of the gas barrier substrate (GS) used in the present invention will be described.

Plastic film layer (S)
Examples of the plastic film layer (S) include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), polycyclohexanedimethanol terephthalate (PCT), and a copolymer of PET and PCT. Various polyester films including copolymer types such as PET-G (manufactured by Eastman Chemical Co.), various polyamide (imide) films including copolymer types such as polyamide 6, polyamide 6,6 or aromatic polyamide and polyimide, polyethylene ( PE), polypropylene (PP), polyolefin films including copolymer types such as cyclic polyolefin, polystyrene films (PS), acrylic films such as polymethyl methacrylate (PMMA) and polyacrylonitrile (PAN), or Films made of these vinyl / (meth) acrylic resin copolymers, polycarbonate (PC) films, polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), polyvinyl fluoride (PVF), polyvinylidene fluoride (PVDF), polychlorotrifluoroethylene (PCTFE), polyethylene tetrafluoroethylene (ETFE), polytetrafluoroethylene (PTFE), tetrafluoroethylene perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene Various halogen-containing resin films such as a copolymer (FEP) can be used. These films may be either stretched or unstretched.

  For these plastic film layers (S), various well-known additives and stabilizers such as antistatic agents, anti-ultraviolet agents, plasticizers and lubricants may be used. Further, corona treatment, low-temperature plasma treatment, ion bombardment treatment, or the like may be performed in terms of improving the adhesion with the primer layer (P) for soft deposition described later. Furthermore, chemical treatment or solvent treatment may be performed. The plastic film layer (S) is not limited by the film thickness.

Primer layer for soft evaporation (P)
The primer layer (P) for soft vapor deposition is the most characteristic layer in the present invention.
Examples of the component (P1) include polyester polyols or isocyanate extension products thereof, for example, succinic acid, glutaric acid, adipic acid, pimelic acid, speric acid, azelaic acid, sebacic acid, brassylic acid, and the like, isophthalic acid , One or more aromatic dibasic acids such as terephthalic acid and naphthalenedicarboxylic acid, ethylene glycol, propylene glycol, butanediol, neopentyl glycol, methylpentanediol, hexanediol, heptanediol, octanediol, nonanediol, Copolyester resin obtained by using at least one kind of aliphatic diol such as aliphatic type such as decanediol and dodecanediol, cycloaliphatic diol and hydrogenated xylylene glycol, and xylylene glycol Use Door can be.

  Furthermore, the hydroxyl groups at both ends of this copolyester are, for example, 2,4- or 2,6-tolylene diisocyanate, xylylene diisocyanate, 4,4′-diphenylmethane diisocyanate, methylene diisocyanate, isopropylene diisocyanate, lysine diisocyanate, 2 , 2,4- or 2,4,4-trimethylhexamethylene diisocyanate, 1,6-hexamethylene diisocyanate, methylcyclohexane diisocyanate, isophorone diisocyanate, 4.4'-dicyclohexylmethane diisocyanate, isopropylidene dicyclohexyl-4,4'- An adduct body composed of an isocyanate compound selected from diisocyanates and the like, or the above isocyanate compound selected from at least one or more; Yuretto body, such as a polyester polyol which has been subjected to chain extension using the isocyanurate can be used.

  Moreover, it is preferable that the glass transition temperature of the said component (P1) is less than 40 degreeC. When the glass transition temperature is 40 ° C. or higher, it is difficult to relax the strain (stress) generated at the interface as a factor of the hardness of the coating agent described above. The glass transition temperature of component (P1) is preferably 25 ° C. or lower, more preferably 10 ° C. or lower.

  The component (P1) is preferably made of a copolyester resin that is amorphous or low crystalline and has a low crystallization rate. When a material having a high crystallization rate and a high crystallinity is used, unevenness of the interface accompanying crystal generation such as crystal nucleation and nucleus growth is likely to occur, which is disadvantageous in terms of adhesion. More preferred is an amorphous polyester polyol, which is advantageous in terms of adhesion because it prevents the occurrence of irregularities associated with crystal formation or does not cause volume shrinkage associated with crystallization. Furthermore, an adhesive effect can be expected. The content described above is an explanation of the definition of “soft” in the present invention.

  The component (P1) can be expected to have an adhesive effect, but there is a concern about blocking at the time of winding by coating. Therefore, it is preferable to form a crosslinked structure with various curing agents. There is no problem as long as the component (P2), which is such a curing agent, is a crosslinking agent that can react with the terminal hydroxyl group or terminal carboxyl group of the polyester polyol.

  Specifically, for the component (P2), it is possible to use, as an isocyanate compound, the material used as the chain extender described above. For example, the polyester polyol leaving the terminal carboxyl group, or the chain extension by the isocyanate compound The polyester polyol resin etc. which gave and formed the urethane bond can be used.

  In addition, a carbodiimide compound can be used as the curing agent for the component (P2). Examples of the carbodiimide compound include N, N′-di-O-toluylcarbodiimide, N, N′-diphenylcarbodiimide, N, N′-di-2,6-dimethylphenylcarbodiimide, N, N′-bis (2,6-diisopropylphenyl) carbodiimide, N, N′-dioctyldecylcarbodiimide, N-triyl-N′-cyclohexylcarbodiimide, N, N′-di-2,2-di-t-butylphenylcarbodiimide, N-triyl-N′-phenylcarbodiimide, N, N′-di-p-nitrophenylcarbodiimide, N, N′-di-p -Aminophenylcarbodiimide, N, N'-di-p-hydroxyphenylcarbodiimide, N, N'-di-cycl Dicyclohexylcarbodiimide, N, and the like N'- di -p- tolyl carbodiimide moth. And what was made into the polyfunctional type by derivatizing these monofunctional substances can be used for the said component (P2).

In addition, as the component (P2), as the cross-linking agent of the transition metal compound represented by the general formula M (OR ′) _n , for example, a cross-linking agent formed by chelating the terminal hydroxyl group with a transition metal is used. Specifically, alkyl titanate, titanium alkoxide, alkyl zirconate, zirconium ammonium carbonate and the like can be used.

  As the phosphorus compound, phosphoric acid or a salt thereof can be used. Specifically, orthophosphoric acid, pyrophosphoric acid, metaphosphoric acid, or alkali metal salts or ammonium salts thereof, particularly trimetaphosphoric acid, tetrametalin. Acid, condensed phosphoric acid such as hexametaphosphoric acid and ultrametaphosphoric acid, or alkali metal salts and ammonium salts thereof can be used. Furthermore, phosphate esters such as triphenyl phosphate can also be used.

When the mixture of the components (P1) and (P2) is further imparted with an anti-blocking effect, or when a hard vapor deposition primer layer (H) described later is provided on the soft vapor deposition primer layer (P), In order to improve the correlation adhesiveness, it is preferable to add the following component (P3).
(P3): a polyol that is incompatible with (P1) and has a glass transition temperature of 40 ° C. or higher, an isocyanate extension of this polyol, or a mixture thereof.

  Moreover, acrylic polyol, carbonate polyol, or a mixture thereof can be suitably used as the component (P3), particularly as a polyol. Specifically, as the acrylic polyol, for example, (meth) acrylic acid, methyl group as methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, t-butyl group , 2-ethylhexyl group, cyclohexyl group such as alkyl (meth) acrylate and other monomers such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate and other hydroxyl group-containing (meth) acrylic monomers are copolymerized Can be mentioned.

  In addition, the component (P3) includes (meth) acrylamide, N-alkyl (meth) acrylamide, N, N′-dialkyl (meth) acrylamide (the alkyl group includes a methyl group, an ethyl group, an n-propyl group, i-propyl group, n-butyl group, i-butyl group, t-butyl group, 2-ethylhexyl group, cyclohexyl group, etc.), N-alkoxy (meth) acrylamide, N, N′-dialkoxy (meth) acrylamide, (As the alkoxy group, amide group-containing monomers such as methoxy group, ethoxy group, butoxy group, isobutoxy group, etc.), N-methylol (meth) acrylamide, N-phenyl (meth) acrylamide and the like can be used.

  In addition, as the component (P3), for example, a copolymer obtained by copolymerizing a glycidyl group-containing monomer such as glycidyl (meth) acrylate or allyl glycidyl ether can be used as the other copolymerization component.

  Examples of the component (P3) include isopropenyl-oxazoline, vinyl isocyanate, allyl isocyanate, styrene, α-methylstyrene, vinyl methyl ether, vinyl ethyl ether, maleic acid, alkylmaleic acid monoester, fumaric acid, It is possible to use a copolymer of monomers such as alkyl fumaric acid monoester, itaconic acid, alkyl itaconic acid monoester, (meth) acrylonitrile, vinylidene chloride, ethylene, propylene, vinyl chloride, vinyl acetate, butadiene and the like.

  The carbonate polyol can be obtained by reacting a carbonate compound and a diol. Examples of such a carbonate compound include dimethyl carbonate, diphenyl carbonate, ethylene carbonate, and the like.

  Examples of the diol include aliphatic diols such as ethylene glycol, propylene glycol, butanediol, neopentyl glycol, methylpentanediol, hexanediol, heptanediol, octanediol, nonanediol, decanediol, dodecanediol, cyclohexanediol, water It is possible to use a carbonate polyol in which a mixture of one or more of an alicyclic diol such as an added xylylene glycol or an aromatic diol such as a xylylene glycol is used, or a polycarbonate polyol subjected to chain extension by the isocyanate compound described above. it can.

  Moreover, it is preferable that the glass transition temperature of the said component (P3) is 40 degreeC or more. When the glass transition temperature is lower than 40 ° C., the antiblocking effect is lost when combined with the components (P1) and (P2). The glass transition temperature of component (P3) is preferably 60 ° C. or higher.

  Further, when providing the hard vapor deposition primer layer (H), when the hard vapor deposition primer layer (H) is acrylic polyol or carbonate polyol, the same material is used as the soft vapor deposition primer layer (P). This is preferable in terms of adhesion of the primer layer for hard vapor deposition (H).

  The primer layer (P) for soft vapor deposition has a mass ratio (P1) / (P3) in the range of 99/1 to 50/50, that is, (P1) :( P3) = 99 to 50: 1 to 50. [Mass%] is preferred. The primer layer (P) for soft vapor deposition has a mass ratio {(P1) + (P3)} / (P2) in the range of 100/5 to 100/100, that is, (P1) + (P3) : (P2) = 100: 5 to 100 [mass%] is preferable.

  If this balance is lost, the material having a high glass transition temperature affects the adhesion to the plastic film layer (S), which is not preferable in terms of moisture and heat resistance. In addition, the primer layer (P) for soft vapor deposition is a coating composition made of a different material, and even when dissolved in a solvent, it is formed into a film by removing the dry solvent after coating, even in a uniform state. A phase separation structure is formed. Assuming that the phase separation structure forms a completely sea-island structure, the surface layer of the soft evaporation primer layer (P) has a skin layer composed of the component (P1), so the component (P3) It is difficult to impart an anti-blocking effect or adhesion to the hard vapor deposition primer layer (H).

  Therefore, it is preferable to combine this complete phase separation structure with a crosslinking agent. This structure control is performed by adding the component (P2) as a crosslinking agent. When the amount of the component (P2) is less than 5% by mass with respect to 100% by mass of the mixture of the components (P1) and (P3), , And decomposing is not performed, causing a blocking problem. Moreover, when using the primer layer (H) for vapor deposition, there exists a possibility that the adhesiveness may be reduced. On the other hand, when the amount of the component (P2) added exceeds 100% by mass with respect to 100% by mass of the mixture of the components (P1) and (P3), the coating layer becomes too homogeneous and the component (P1 ) And (P3). This content is highly likely to be accompanied by a decrease in wet heat resistance. This is the same as the reason why the components (P1) and (P3) are preferably incompatible, and when the components (P1) and (P3) are incompatible, they are mixed together uniformly. May be accompanied by a decrease in wet heat resistance.

The primer layer (P) for soft vapor deposition may be added with the following component (P4) as necessary.
(P4): an organosilane represented by the general formula R—Si (OR ′) ₃ or a hydrolyzate thereof, one or more metal alkoxides represented by the general formula M (OR ′) _n or a hydrolyzate thereof, Or a mixture thereof [wherein R is a functional group selected from an alkyl group, a (meth) acryloyl group, a vinyl group, an amino group, an epoxy group, and an isocyanate group, R ′ is an alkyl group, and M is a metal ion. And n is the valence of the ion. ].

Specifically, examples of the organosilane represented by the general formula R—Si (OR ′) ₃ or a hydrolyzate thereof include, for example, ethyltrimethoxysilane, (meth) acryloxypropyltrimethoxysilane, vinyltrimethoxysilane. , Glycidoxypropyltrimethoxysilane, etc. General formula R—Si (OR ′) ₃ (R = alkyl group, (meth) acryloyl group, vinyl group, amino group, epoxy group, isocyanate, R ′ is an alkyl group, etc. And the hydrolyzate thereof. Among these, glycidoxytrimethoxysilane containing an epoxy group, epoxycyclohexylethyltrimethoxysilane, isocyanatepropyltrimethoxysilane containing an isocyanate group, and the like are particularly preferable. These organosilanes are not limited to monomers, and compounds such as dimers and trimers can also be used depending on the structure.

Examples of one or more metal alkoxides represented by the general formula M (OR ′) _n or a hydrolyzate thereof include a general formula M (OR ′) _n (M is Si, Al, etc.) such as tetraethoxysilane and tripropoxyaluminum. , Ti, Zr and the like, and R ′ is an alkyl group.), Or a hydrolyzate thereof.

  As a method for obtaining a hydrolyzate of these compounds, a known method such as a method of performing hydrolysis by directly adding an acid or an alkali to these compounds can be used. Moreover, you may add the reaction catalyst which accelerates | stimulates reaction, such as a tin compound, as needed.

  By adding the component (P4), it is possible to improve the adhesion to the vapor deposition layer (V). Moreover, it is possible to give appropriate hardness in providing a vapor deposition layer (V).

  Although there is no restriction | limiting in particular about the addition amount of the said component (P4), Since excess addition will be saturated in the point of contact | adherence of a vapor deposition layer (V), the said component (P1) or the said component (P1) and The upper limit is preferably 100% by mass with respect to 100% by mass of the mixture of (P3).

  Summarizing the function of each composition of the primer layer (P) for soft vapor deposition, the above component (P1) is improved in adhesion due to adhesion, reduction of adhesive interface strain at high temperature and high humidity, relaxation of residual stress, As for P3), when providing the primer layer (H) for blocking prevention and hard vapor deposition, the anti-blocking effect is mentioned first about the adhesion provision and the said component (P2). In addition, the functions of both the components (P1) and (P3) are made compatible (control of the phase separation structure by forming a crosslinked structure). About the said component (P4), it is possible to give the hardness of the primer layer (P) for soft vapor deposition suitable for forming vapor deposition layer (V) while providing adhesion with vapor deposition layer (V). It becomes. With such a design, it is possible to provide a gas barrier substrate (GS) having excellent wet heat resistance.

Primer layer for hard evaporation (H)
The hard vapor deposition primer layer (H) may or may not be provided depending on the components of the soft vapor deposition primer layer (P), but the hard vapor deposition primer layer (H) is a vapor deposition layer (V ) Is preferable because it is designed specifically for close contact with the adhesive. In terms of components, the contents including the contents described in the cited document 9 are included.

That is, the primer layer for hard vapor deposition (H) is composed of a compound containing at least the following component (H1) and one or both of (H2) and (H3).
(H1): Polyester polyol having a glass transition temperature of 40 ° C. or higher, an isocyanate extension product thereof, an acrylic polyol or an isocyanate extension product thereof, a carbonate polyol or an isocyanate extension product thereof, or a mixture thereof (note that an acrylic polyol or a carbonate polyol is used) When used, (P3) and (H1) may be the same).
(H2): at least one cross-linking agent selected from an isocyanate compound, a carbodiimide compound, a transition metal compound represented by the general formula M (OR ′) _n , and a phosphorus compound [where R ′ is an alkyl group M is a metal ion and n is the valence of the ion. ].
(H3): an organosilane represented by the general formula R—Si (OR ′) ₃ or a hydrolyzate thereof, one or more metal alkoxides represented by the general formula M (OR ′) _n or a hydrolyzate thereof, Or a mixture thereof [wherein R is a functional group selected from an alkyl group, a (meth) acryloyl group, a vinyl group, an amino group, an epoxy group, and an isocyanate group, R ′ is an alkyl group, and M is a metal ion. And n is the valence of the ion. ].

  A major feature of this primer layer for hard vapor deposition (H) is that the main component “polyol” has a glass transition temperature of 40 ° C. or higher, and the adhesion of the vapor deposition layer (V) is improved. This is intended to increase the hardness of the film. Of course, it is also advantageous in terms of preventing blocking during coating.

  For the components (H1), (H2), and (H3), the same components as the components (P1), (P2), (P3), and (P4) of the primer layer (P) for soft deposition are used. it can. Moreover, when the said component (H1) is a polyester polyol, what controlled the glass transition temperature to 40 degreeC or more by controlling the copolymerization component similar to the component (P1) of the said primer layer for soft vapor deposition is used. be able to.

Vapor deposition layer (V)
The vapor deposition layer (V) is composed of a vapor deposition film of an inorganic oxide such as aluminum oxide, silicon oxide, tin oxide, magnesium oxide, or a mixture thereof. As the vapor deposition layer (V), in terms of a gas barrier film, it is preferable to use a transparent film having gas barrier properties such as oxygen and water vapor, and it is preferable to use aluminum oxide or silicon oxide. However, it is not limited to the inorganic oxides described above, and an inorganic vapor deposition film having a function other than gas barrier properties can also be developed as various functional vapor deposition films by providing a coating layer having excellent wet heat resistance in the present invention. Is possible.

  The optimum condition of the thickness of the vapor deposition layer (V) varies depending on the type and configuration of the inorganic compound to be used, but generally it is preferably in the range of 5 to 300 nm, and the value is appropriately selected. In terms of the gas barrier function, if the film thickness is less than 5 nm, a uniform film may not be obtained or the film thickness may not be sufficient, and the function as a gas barrier material may not be sufficiently achieved. On the other hand, when the film thickness exceeds 300 nm, flexibility cannot be maintained in the thin film, and the thin film may be cracked due to external factors such as bending and pulling after the film formation.

  As a method for forming the vapor deposition layer (V), it can usually be formed by vacuum vapor deposition, but other thin film formation methods such as sputtering, ion plating, plasma vapor deposition (CVD), etc. It can also be used. As the heating means of the vacuum deposition apparatus by the vacuum deposition method, an electron beam heating method, a resistance heating method, or an induction heating method is preferable. In order to improve the adhesion between the thin film and the base material and the denseness of the thin film, a plasma assist method or an ion It is also possible to use a beam assist method. In addition, in order to increase the transparency of the deposited film, reactive deposition such as blowing oxygen gas may be performed during the deposition.

Overcoat layer for vapor deposition (O)
A vapor deposition overcoat layer (O) may be provided on the vapor deposition layer (V) in terms of improving the gas barrier properties of the gas barrier film described above.
The overcoat layer (O) for vapor deposition is composed of a compound containing the following components (O1) and (O2).
(O1): Water-soluble polymer.
(O2): an organosilane represented by the general formula R—Si (OR ′) ₃ or a hydrolyzate thereof, one or more metal alkoxides represented by the general formula M (OR ′) _n or a hydrolyzate thereof, Phosphorus compounds, or a mixture thereof [wherein R is a functional group selected from an alkyl group, a (meth) acryloyl group, a vinyl group, an amino group, an epoxy group, an isocyanate group, R ′ is an alkyl group, etc. M is a metal ion, and n is the valence of the ion. ].

  Specifically, water-soluble polymers such as polyvinyl alcohol, polyvinyl pyrrolidone, starch, methyl cellulose, carboxymethyl cellulose, sodium alginate and the like can be used for the component (O1), and among them, polyvinyl alcohol is particularly used. preferable. The component (O2) is blended in consideration of adhesion to the vapor deposition layer (V), crosslinkability of the component (O1), and the like, and the same component as the component (P4) is used. it can.

  The soft deposition primer layer (P), the hard deposition primer layer (H), and the deposition overcoat layer (O) can be provided using a known technique, for example, gravure coating, gravure Various coating methods such as reverse coating, roll coating, reverse roll coating, micro gravure coating, comma coating, air knife coating, Mayer bar coating, dip coating, die coating, and spray coating can be used. In addition, the above-described soft vapor deposition primer layer (P) and hard vapor deposition primer layer (H) may be individually coated, but the soft vapor deposition primer layer (P) is a hard vapor deposition primer layer ( Since it is harder to block than H), it may be applied in-line with 2 heads.

  The above is the configuration of the gas barrier base material (GS) effective for wet heat resistance adhesion, and the solar cell back surface sealing of the present invention is performed by laminating the gas barrier base material (GS) and the weather resistant base material (DS). Sheet can be obtained.

  Specifically, solar cell back surface sealing sheets 1A and 1B shown in FIGS. 1 (a) and 1 (b) are provided with a weather resistant substrate (U) on both sides of the gas barrier substrate (GS) via an adhesive layer (U). DS) is bonded. The configurations shown in FIGS. 1 (a) and 1 (b) are merely examples, and other layers may be interposed depending on the required function, or more layers may be configured. Further, in these configurations, the surface to be bonded with the ethylene-vinyl acetate copolymer that is the filler of the solar cell as the solar cell back surface sealing sheet is either the outermost layer or the innermost layer of the weather resistant substrate (DS). May be used for the bonding surface.

Weather resistant substrate (DS)
For the weather-resistant substrate (DS), for example, a polyester substrate selected from polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), polycyclohexanedimethanol-terephthalate (PCT), Polycarbonate base material, polyvinyl fluoride (PVF), polyvinylidene fluoride (PVDF), polychlorotrifluoroethylene (PCTFE), polyethylene tetrafluoroethylene (ETFE), polytetrafluoroethylene (PTFE), tetrafluoroethylene perfluoroalkyl A fluorine-based substrate selected from vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), an acrylic substrate, or the like can be used. Moreover, it is not limited to these materials, polyolefin resin, polyamide-type resin, polyarylate-type resin, etc. can be suitably selected and used in consideration of heat resistance, strength physical properties, electrical insulation, and the like.

  When a polyester substrate is used as the weather resistant substrate (DS), it is obtained by using a polybasic acid or an ester-forming derivative thereof and a polyol or an ester-forming derivative thereof. Acid, isophthalic acid, phthalic acid, phthalic anhydride, 2,6-naphthalenedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, adipic acid, sebacic acid, trimellitic acid, pyromellitic acid, dimer acid, maleic acid, itaconic acid As the polyol component, ethylene glycol, 1,4-butanediol, diethylene glycol, dipropylene glycol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, trimethylolpropane, Pentaerythritol, xylene glycol, dimethylo It can be obtained by using one or two or more polyol components containing propane, poly (ethylene oxide) glycol, poly (tetramethylene oxide) glycol, carboxylic acid group, sulfonic acid group, amino group, or salts thereof. Polyester can be used. In addition, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), and polycyclohexanedimethanol-terephthalate (PCT) described above can be generally used.

  However, polyester resins, particularly polyethylene terephthalate, are materials that are concerned about hydrolysis. Therefore, when polyethylene terephthalate is used for the weather resistant substrate (DS), the number average molecular weight is in the range of 18000 to 40,000, the cyclic oligomer content is 1.5 mass% or less, and the intrinsic viscosity is 0.5 dl / g or more. It is preferable to use a material having hydrolysis resistance. Such a polyester resin may be produced by a solid phase polymerization method capable of increasing the number average molecular weight without increasing the amount of terminal carboxylic acid that acts as an acid catalyst in the hydrolysis of the polyester resin, What sealed the acid group with the carbodiimide type compound, the epoxy-type compound, and the oxazoline type compound can be used suitably. In addition, when there is a concern about the effect of shrinkage due to heat at the time of manufacturing a solar cell module, a polyester resin having a heat shrinkage rate of 1% or less, preferably 0.5% or less is obtained by performing an annealing treatment. Can be used. When weather resistance is required, UV absorbers such as benzophenone, benzotriazole, and triazine, hindered phenol-based, phosphorus-based, sulfur-based, tocopherol-based antioxidants, hindered amine-based light stabilizers are also appropriately used. Can be blended.

  The weather-resistant substrate (DS) used for the solar cell backside sealing sheet may be transparent, but a white polyester film is preferably used from the viewpoint of improving the power generation efficiency of the solar cell element. In particular, when the solar cell back surface sealing sheet has a multilayer structure, it is possible to provide a white polyester film at least on the weather-resistant substrate (DS) to be bonded to the filler. The white polyester film used at this time is a pigment dispersion type to which white additives such as titanium oxide, silica, alumina, calcium carbonate, barium sulfate, etc. are added, or a polymer or fine particles incompatible with polyester, and is biaxially stretched. For example, a fine foam type that is whitened by forming voids at the blend interface can be used. In the micro-foaming type, it is preferable to use a polyolefin-based resin such as polyethylene, polypropylene, polybutene, and polymethylpentene as a polymer that is incompatible with polyester. Moreover, polyalkylene glycol or a copolymer thereof can be used as a compatibilizing agent as necessary. As the fine particles, organic particles or inorganic particles can be used. Specific examples include silicon particles, polyimide particles, crosslinked styrene-divinylbenzene copolymer particles, crosslinked polyester particles, and fluorine-based particles. As the inorganic particles, calcium carbonate, silicon dioxide, barium sulfate, or the like can be used.

Adhesive (U)
For the adhesive (U), for example, a polyurethane resin obtained by allowing a bifunctional or higher functional isocyanate compound to act on a main component such as polyester polyol, polyether polyol, acrylic polyol, and carbonate polyol can be used. Polyester polyols are aliphatic bases such as succinic acid, glutaric acid, adipic acid, pimelic acid, speric acid, azelaic acid, sebacic acid, and brassylic acid, and aromatic dibasic bases such as isophthalic acid, terephthalic acid, and naphthalenedicarboxylic acid. One or more acids, and ethylene glycol, propylene glycol, butanediol, neopentyl glycol, methylpentanediol, hexanediol, heptanediol, octanediol, nonanediol, decanediol, dodecanediol and other aliphatic systems, cyclohexanediol, It can be obtained by using one or more alicyclic type diols such as hydrogenated xylylene glycol and aromatic diols such as xylylene glycol.

  Furthermore, the hydroxyl groups at both ends of this polyester polyol are, for example, 2,4- or 2,6-tolylene diisocyanate, xylylene diisocyanate, 4,4′-diphenylmethane diisocyanate, methylene diisocyanate, isopropylene diisocyanate, lysine diisocyanate, 2, 2,4- or 2,4,4-trimethylhexamethylene diisocyanate, 1,6-hexamethylene diisocyanate, methylcyclohexane diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, isopropylidene dicyclohexyl-4,4'-diisocyanate A single adduct of an isocyanate compound selected from the above, or an adduct comprising the above isocyanate compound selected from at least one or more It can be used burette body, and polyester urethane polyol chain extension with isocyanurate.

  As the polyether polyol, ether-based polyols such as polyethylene glycol and polypropylene glycol, and polyether urethane polyols on which the above-described isocyanate compounds are used as chain extenders can be used. As the acrylic polyol, an acrylic resin polymerized using the above-described acrylic monomer can be used. The carbonate polyol can be obtained by reacting a carbonate compound and a diol. As the carbonate compound, dimethyl carbonate, diphenyl carbonate, ethylene carbonate and the like can be used. Diols include ethylene glycol, propylene glycol, butanediol, neopentyl glycol, methylpentanediol, hexanediol, heptanediol, octanediol, nonanediol, decanediol, dodecanediol, and other aliphatic diols, cyclohexanediol, hydrogenated xylylene. Carbonate polyol using a mixture of one or more selected from alicyclic diols such as length reels and aromatic diols such as xylylene glycol, or polycarbonate urethane polyols subjected to chain extension with the isocyanate compounds described above Can be used. These various polyols may be used alone or in the form of a blend of two or more depending on the required function and performance. Moreover, it can use as a polyurethane-type adhesive agent by using the isocyanate type compound mentioned above as a hardening | curing agent with respect to these main ingredients.

  Since the polyurethane-based adhesives described above may be accompanied by deterioration in an accelerated environment under weather resistance or high temperature and high humidity, carbodiimide compounds, oxazoline compounds, epoxy compounds, phosphorus compounds, etc. are used as compounds that suppress the acceleration of deterioration. It is also possible to mix.

  Examples of the carbodiimide compound include N, N′-di-O-toluylcarbodiimide, N, N′-diphenylcarbodiimide, N, N′-di-2,6-dimethylphenylcarbodiimide, N, N′-bis (2,6 -Diisopropylphenyl) carbodiimide, N, N'-dioctyldecylcarbodiimide, N-triyl-N'-cyclohexylcarbodiimide, N, N'-di-2,2-di-t-butylphenylcarbodiimide, N-triyl-N ' -Phenylcarbodiimide, N, N'-di-p-nitrophenylcarbodiimide, N, N'-di-p-aminophenylcarbodiimide, N, N'-di-p-hydroxyphenylcarbodiimide, N, N'-di- Cyclohexylcarbodiimide, N, N′-di-p-toluylcarbodiimide, etc. Can.

  As the oxazoline compound, monooxazoline compounds such as 2-oxazoline, 2-methyl-2-oxazoline, 2-phenyl-2-oxazoline, 2,5-dimethyl-2-oxazoline, 2,4-diphenyl-2-oxazoline, 2,2 ′-(1,3-phenylene) -bis (2-oxazoline), 2,2 ′-(1,2-ethylene) -bis (2-oxazoline), 2,2 ′-(1,4- And dioxazoline compounds such as butylene) -bis (2-oxazoline) and 2,2 ′-(1,4-phenylene) -bis (2-oxazoline).

  Epoxy compounds include diglycidyl ethers of aliphatic diols such as 1,6-hexanediol, neopentyl glycol, polyalkylene glycol, sorbitol, sorbitan, polyglycerol, pentaerythritol, diglycerol, glycerol, trimethylolpropane, etc. Polyglycidyl ether of aliphatic polyols, polyglycidyl ether of alicyclic polyols such as cyclohexanedimethanol, aliphatic and aromatic such as terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, trimellitic acid, adipic acid, sebacic acid Diglycidyl ester of polycarboxylic acid, or polyglycidyl ester, resorcinol, bis- (p-hydroxyphenyl) methane, 2,2-bis- (p-hydroxyphenyl) propane Diglycidyl ether of polyphenols such as tris- (p-hydroxyphenyl) methane, 1,1,2,2, -tetrakis (p-hydroxyphenyl) ethane, or polyglycidyl ether, N, N′-diglycidylaniline N, N, N-diglycidyltoluidine, N, N, N ′, N′-tetraglycidyl-bis- (p-aminophenyl) methane, N-glycidyl derivatives of amines, triglycidyl derivatives of aminofails, Examples thereof include triglycidyl tris (2-hydroxyethyl) isocyanurate, triglycidyl isocyanurate, orthocresol type epoxy, phenol novolac type epoxy and the like.

  Examples of phosphorus compounds include tris (2,4-di-t-butylphenyl) phosphite, tetrakis (2,4-di-t-butylphenyl) 4,4′-biphenylenephosphonite, bis (2,4 -Di-t-butylphenyl) pentaerythritol-di-phosphite, bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol-di-phosphite, 2,2-methylenebis (4,6 -Di-t-butylphenyl) octyl phosphite, 4,4'-butylidene-bis (3-methyl-6-tert-butylphenyl-di-tridecyl) phosphite, 1,1,3-tris (2-methyl -4-ditridecyl phosphite-5-t-butyl-phenyl) butane, tris (mixed mono and di-nonylphenyl) phosphite, tris (nonylphenyl) phosphite 4,4'-isopropylidene-bis (phenyl - dialkyl phosphite), and the like.

When the above-mentioned weather resistant substrate (DS) and gas barrier substrate (GS) are bonded together with an adhesive (U), a known technique such as dry lamination can be used, specifically, gravure coating, Adheres to both sides of gas barrier substrate (GS) by laminating polyurethane adhesive in the range of 0.1-10 g / m ² as dry solid content using methods such as roll coating, bar coating, reverse coating, etc. The weather-resistant substrate (DS) can be bonded through the agent (U).

  At this time, the weather resistant substrate (DS) can be subjected to a surface treatment for improving adhesion such as corona treatment, flame treatment, and plasma treatment, if necessary. Further, if necessary, an easy-adhesion coat layer for adhering the solar cell back surface sealing sheet to EVA as a solar cell filler, for example, a layer made of polyester, polyurethane, acrylic, or a mixture thereof. You may provide in a weather-resistant base material (DS) side.

<Solar cell module>
Next, a solar cell module to which the present invention is applied will be described.
The solar cell module to which the present invention is applied is, for example, like a solar cell module 10 shown in FIG. 2, a solar cell 13 as a photovoltaic element provided with a glass plate 11 and wiring 12, and the back side of the solar cell. A glass plate 11 and a sun provided with a sealing sheet 1A (or a solar cell back surface sealing sheet 1B), a filler layer 14, and a frame (spacer) 15 fixed by the frame (spacer) 15. Between the battery back surface sealing sheet 1A (1B), the solar cell element 13 is disposed and the filler layer 14 is filled.

As shown in FIGS. 3A and 3B, the solar cell module 10 is manufactured through the following steps (1) to (4).
(1) On the heated top plate 100 (about 120 to 160 ° C.), the glass plate 11, the filler layer 14, the solar battery cell 13, the filler layer 14, and the solar battery back surface sealing sheet 1A. (1B) is set in a sequentially stacked state.
(2) The chambers 101 and 102 are evacuated.
(3) The chamber 101 is opened to the atmosphere, and the heat-resistant rubber sheet 103 is brought into close contact with the solar cell module 10.
(4) The ethylene vinyl acetate copolymer as the filler layer 14 is melted by the heat and pressure, embedded between the solar cells 13, and the glass plate 11 sandwiching the solar cells 13 and the solar cell back surface sealing While adhering to the stop sheet 1A (1B), the filler layer 14 is cross-linked and solidified.

  The step (4) is classified into a case where a crosslinking reaction is performed in an oven provided on a separate line after lamination and a case where a crosslinking reaction is performed inside the laminator. The former is a type called standard cure, and the latter is a type called fast cure. Usually, the material used as the filler layer of the solar cell module is an ethylene-vinyl acetate copolymer having a vinyl acetate content of 10 to 40% by weight in order to ensure the heat resistance and physical strength of the solar cell. In addition, the ethylene-vinyl acetate copolymer is crosslinked by heat or light.

  When thermal crosslinking is performed, an organic peroxide is usually used, and one that decomposes at a temperature of 70 ° C. or higher to generate radicals is used. Usually, those having a decomposition temperature of 50 ° C. or more with a half-life of 10 hours are used, and 2,5-dimethylhexane-2,5-dihydroxyperoxide, 2,5-dimethyl-2,5-di (t-butyl) Peroxy) hexyne-3, di-t-butyl peroxide, t-butylcumyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, dicumyl peroxide, α, α '-Bis (t-butylperoxyisopropyl) benzene, n-butyl-4,4-bis- (t-butylperoxy) valerate, t-butylperoxybenzoate, benzoyl peroxide and the like are used.

  In the case of performing photocuring, a photosensitizer is used, which is a hydrogen abstraction type (bimolecular reaction type), such as benzophenone, methyl orthobenzoylbenzoate, 4-benzoyl-4′-methyldiphenyl sulfide, isopropylthioxanthone, etc. Is used. Further, as the internal cleavage type initiator, benzoin ether, benzyldimethyl ketal, etc., α-hydroxyalkylphenone type, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, Alkylphenylglyoxylate, diethoxyacetophenone and the like can be used. Further, as α-aminoalkylphenone type, 2-methyl-1- [4 (methylthio) phenyl] -2-morpholinopropane-1,2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -Butanone-1 etc., acylphosphine oxide etc. are also used.

  A silane coupling agent is also blended in consideration of adhesion to the glass plate 11 constituting the solar cell module 10, and vinyltriethoxysilane, vinyltris (β-methoxyethoxy) silane, γ-methacryloxypropyltrimethoxy Silane, vinyltriacetoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-chloropropylmethoxysilane, vinyl Trichlorosilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β (aminoethyl) -γ-aminopropyltrimethoxysilane and the like are blended.

  Furthermore, an epoxy group-containing compound may be blended for the purpose of promoting adhesiveness and curing. Examples of the epoxy group-containing compound include triglycidyl tris (2-hydroxyethyl) isocyanurate, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, acrylic glycidyl ether, 2-ethylhexyl glycidyl ether, phenyl glycidyl ether, phenol glycidyl ether, pt-butylphenyl glycidyl ether, adipic acid diglycidyl ester, o-phthalic acid diglycidyl ester , Glycidyl methacrylate, butyl glycidyl ether and other compounds, oligomers containing an epoxy group with a molecular weight of several hundred to several thousand, and polymers with a weight average molecular weight of several thousand to several hundred thousand. Some cases are there.

  Furthermore, an acryloxy group, methacryloxy group or allyl group-containing compound is added for the purpose of improving the cross-linking, adhesiveness, mechanical strength, heat resistance, moist heat resistance, weather resistance, etc. of the filler layer 14, and (meth) Acrylic acid derivatives such as their alkyl esters and amides are most common. In this case, as the alkyl group, in addition to an alkyl group such as methyl, ethyl, dodecyl, stearyl, lauryl, cyclohexyl group, tetrahydrofurfuryl group, aminoethyl group, 2-hydroxyethyl group, 3-hydroxypropyl group, A 3-chloro-2-hydroxypropyl group and the like can be mentioned. Further, esters of (meth) acrylic acid and polyfunctional alcohols such as ethylene glycol, triethylene glycol, polyethylene glycol, glycerin, trimethylolpropane, pentaerythritol and the like are also used. A typical amide is acrylamide. Examples of the allyl group-containing compound include triallyl cyanurate, triallyl isocyanurate, diallyl phthalate, diallyl isophthalate, diallyl maleate, and the like.

  Furthermore, an inorganic compound for imparting flame retardancy, an ultraviolet absorber for imparting weather resistance, and an antioxidant for preventing oxidative degradation are variously blended. That is, it can be mentioned that the ethylene-vinyl acetate copolymer constituting the solar cell module 10 is a resin composition in which various additives are blended in order to satisfy the functions required for the solar cell module.

  The solar cell module 10 manufactured as described above evaluates not only the environment actually used as the solar cell module but also the solar cell module by using the solar cell back surface sealing sheet 1A (1B). Even in the accelerated evaluation under high temperature and high humidity, which is considered in this case, it is possible to maintain not only the appearance defect accompanying delamination but also the electric output characteristics as a solar cell.

  Hereinafter, the effects of the present invention will be made clearer by examples. In addition, this invention is not limited to a following example, In the range which does not change the summary, it can change suitably and can implement.

<Gas barrier substrate (GS)>
Primer layer for soft evaporation (P)
In this example, the following materials were used as the primer layer (P) for soft vapor deposition.
[P- (1)] (in this example, comparative example)
The blend ratio of the isocyanate compound ((P2): IPDI adduct) to the polyester polyol (P1) having a glass transition temperature (Tg) = 7 ° C. is (P1) / (P2) = 100/1 (solid content ratio) A solvent-based primer composition (P).
[P- (2)]
In the above [P- (1)], a solvent-based primer composition (P) in which the mixing ratio is (P1) / (P2) = 100/25 (solid content ratio).
[P- (3)]
In the above [P- (2)], an acrylic polyol (P3) having a glass transition temperature (Tg) = 85 ° C. is blended, and the blending ratio of the polyester polyol (P1) and the acrylic polyol (P3) is (P1) / (P3 ) = 75/25 (solid content ratio), and a solvent-based primer composition (P) adjusted to (P1) :( P2) :( P3) = 75: 25: 25 (solid content ratio).
[P- (4)] (in this example, comparative example)
In the above [P- (3)], the blending ratio of the polyester polyol (P1) and the acrylic polyol (P3) is (P1) / (P3) = 25/75 (solid content ratio), and the blending ratio is (P1) : (P2): (P3) = Solvent-based primer composition (P) adjusted to 25:25:75 (solid content ratio).
[P- (5)]
In the above [P- (3)], a primer composition (P) comprising a polyester polyol (P3) having a glass transition temperature (Tg) = 62 ° C. instead of an acrylic polyol having a glass transition temperature (Tg) = 85 ° C. .
[P- (6)] (in this example, comparative example)
In the above [P- (4)], a primer composition (P) containing a polyester polyol (P3) having a glass transition temperature (Tg) = 62 ° C. instead of an acrylic polyol having a glass transition temperature (Tg) = 85 ° C. .
[P- (7)] (in this example, comparative example)
In the above [P- (3)], a solvent-based primer composition (P) in which the blending ratio is adjusted to (P1) :( P2) :( P3) = 75: 1: 25 (solid content ratio).
[P- (8)]
In the above [P- (3)], a solvent-based primer composition (P) in which the blending ratio is adjusted to (P1) :( P2) :( P3) = 75: 100: 25 (solid content ratio).
[P- (9)] (in this example, comparative example)
In the above [P- (3)], the solvent-based primer composition (P) in which the blending ratio was adjusted to (P1) :( P2) :( P3) = 75: 150: 25 (solid content ratio)
[P- (10)]
In the above [P- (3)], a silane coupling agent (P4) is further blended, and the blending ratio is (P1) :( P2) :( P3) :( P4) = 75: 25: 25: 25 (solid Solvent-based primer composition (P) adjusted to a fractional ratio).
[P- (11)]
In the above [P- (3)], a primer composition (P) in which the isocyanate compound is changed to a polyfunctional derivative of diphenylcarbodiimide.
[P- (12)]
A primer composition (P) in which the isocyanate compound is changed to titanium isopropoxide in the above [P- (3)].
[P- (13)]
In the above [P- (3)], a primer composition (P) in which an isocyanate compound is changed to a phosphate ester compound.
[P- (14)]
In the above [P- (3)], the polyester polyol (P1) has a glass transition temperature (Tg) = 30 ° C. low-crystalline (low crystallization rate) polyester polyol emulsion, and the acrylic polyol has a glass transition temperature (Tg) = An aqueous primer composition (P) in which an acrylic emulsion at 85 ° C. is blended and further changed to an isocyanate curing agent (P2) for aqueous urethane.

Primer layer for hard evaporation (H)
In this example, the following materials were used as the primer layer (H) for hard vapor deposition.
[H- (1)]
Solvent-based primer prepared by adjusting the isocyanate compound (IPDI adduct) and the silane coupling agent to 100/60/25 (solid content ratio) with respect to an acrylic polyol having a glass transition temperature (Tg) = 85 ° C. Composition (H).
[H- (2)]
A solvent-based primer composition (H) prepared by adjusting an isocyanate compound (IPDI adduct) to 100/20 (solid content ratio) with respect to a polyester polyol having a glass transition temperature (Tg) = 62 ° C.

<Evaluation results of samples 1 to 14>
Here, the feature of the present invention is that the soft vapor deposition primer layer (P) which is easy to block has a material composition which is difficult to block. In samples 1 to 14 shown in Table 1, the primer composition (P) of the above [P- (1)] to [P- (14)] is coated on a polyethylene terephthalate substrate, and the coating substrate is blocked. Whether the modified state of the primer layer (P) for soft deposition is evaluated or not is determined. Specifically, this evaluation was evaluated by ○, Δ, and ×, and Δ or more was regarded as acceptable. That is, if it is evaluation more than (triangle | delta), when using for the solar cell back surface sealing sheet mentioned later, it can be used also as a primer layer (P) layer single-piece | unit for soft vapor deposition.

(Samples 15 to 28)
<Production of gas barrier substrate (GS)>
Next, a gas barrier substrate (DS) was prepared using the soft deposition primer layer (P) and the hard deposition primer layer (H) prepared above.
Specifically, a polyethylene terephthalate and polyethylene naphthalate film having a thickness of 12 μm was used as the plastic film layer (S). The soft deposition primer layer (P) or the hard deposition primer layer (H) was provided in the range of 0.1 to 0.5 g / m ² by a gravure coating method. Table 2 shows details of samples 15 to 28 using the soft deposition primer layer (P) and the hard deposition primer layer (H). Further, there are cases where these two kinds of primer layers are laminated as a multi-layer as required. At that time, a multi-layer coating layer is provided inline by gravure coating of two heads. A silica vapor deposition layer (V) having a thickness of 30 nm was provided by a PVD method on the plastic film (S) provided with the primer layer (P) for soft vapor deposition and the primer layer (H) for hard vapor deposition. Thereafter, an aqueous overcoat layer (O) for vapor deposition mainly composed of polyvinyl alcohol and tetraethoxysilane was provided by gravure coating.

<Production of solar cell back surface sealing sheet>
Next, solar cell back surface sealing sheets of Samples 15 to 28 shown in Table 2 were produced using the produced gas barrier substrate (DS). Specifically, as the weather-resistant substrate (DS), a fluorine-based film such as polyvinyl fluoride can be used, but in this example, a weather-resistant polyester substrate was used. This weather-resistant polyester base material is a polyester resin having a high molecular weight in which the terminal carboxyl group is reduced by solid-phase polymerization of the polyester resin and the number average molecular weight is further increased, and the oligomer content is 0.5% by mass, The number average molecular weight is 19500, and the intrinsic viscosity is 0.7 d / g. After forming this polyester resin into a film by cast film formation, a 50 μm-thick polyethylene terephthalate film, which has been annealed to a thermal shrinkage rate of 0.5% or less, is dry laminated using a polyurethane adhesive. Laminated. Finally, a solar substrate formed by sequentially laminating a weather resistant substrate (DS), an adhesive layer (U), a gas barrier substrate (GS), an adhesive layer (U), and a weather resistant substrate (DS). A battery back surface sealing sheet was prepared.

<Production of solar cell module>
Next, solar cell modules of Examples 15 to 28 were produced using the solar cell back surface sealing sheet. Specifically, a standard cure type ethylene-vinyl acetate copolymer resin composition was used as a filler for a solar cell module. The solar cell used was polycrystalline silicon. A solar cell sandwiched between ethylene-vinyl acetate copolymer sheets having the same size and a thickness of 600 μm was placed on an A4 size tempered glass, and a solar cell back surface sealing sheet was further disposed thereon. Further, after preheating at 40 ° C. for 3 minutes in advance, lamination was performed at 150 ° C. under conditions of evacuation for 6 minutes, pressure bonding for 8 minutes, and pressure of 1 atm. Thereafter, it was stored in an oven heated to 150 ° C. for 30 minutes to allow the crosslinking reaction to proceed. Then, the solar cell module was produced by performing the frame | frame by the adhesion | attachment of a terminal box and an aluminum frame.

  In this example, the conditions for providing the vapor deposition layer (V) and the vapor deposition overcoat layer (O) were fixed, and were set to have substantially the same water vapor barrier property as the solar cell back surface sealing sheet. And the barrier fall after a promotion evaluation, the external appearance defect, and the output characteristic as a solar cell were evaluated.

<Evaluation of solar cell back surface sealing sheet>
For the solar cell back surface sealing sheets of Samples 15 to 28, the laminate strength was measured by T-type peeling at a crosshead speed of 300 mm / min with Tensilon, and the peeling location was further identified by IR or XPS. The wet heat adhesion of the product (P) was evaluated. The storage environment is PCT (accelerated test with pressurized steam) 105 ° C.-100% relative humidity-168 hours. About the water vapor | steam barrier property calculated | required as a sheet | seat for solar cell back surface sealing | blocking, it measured using the modern control company's mocon, and evaluated the deterioration degree of the barrier property before and behind the evaluation. In addition, this evaluation will also be a pass if it is evaluation more than (triangle | delta).

<Evaluation of solar cell module>
When this solar cell module was stored for 3000 hours in an 85 ° C.-85% RH environment, particularly the appearance of the solar cell back surface sealing sheet and the output characteristics of the solar cell were evaluated. This storage environment is almost the same accelerated test environment as PCT105 ° C-100% RH-168h described above.

<Evaluation results of samples 15 to 28>
From the evaluation results shown in Table 2, by using the soft vapor deposition primer layer (P) that satisfies the conditions of the present invention, the gas barrier property (GS) of the gas barrier substrate (GS) can be improved even in a severe storage environment at high temperature and high humidity. Improvement effect was observed. As a result, it has been found that output characteristics as a solar cell can be maintained. In particular, regarding the adhesion, it was confirmed that the composition and blending ratio of the primer layer (P) for soft vapor deposition have a particular influence.

It is sectional drawing which shows the solar cell back surface sealing sheet to which this invention is applied. It is sectional drawing which shows one structural example of a solar cell module. It is a schematic diagram which shows the manufacturing process of a solar cell module.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1A, 1B ... Sheet | seat for solar cell back surface sealing 10 ... Solar cell module 11 ... Glass plate 12 ... Wiring 13 ... Solar cell 14 ... Filler layer 15 ... Frame body GS ... Gas barrier base material DS ... Weatherproof base material S ... Plastic film layer P ... Primer layer for soft deposition H ... Primer layer for hard deposition V ... Deposition layer O ... Overcoat layer for deposition U ... Adhesive

Claims (5)

A solar cell back surface sealing sheet having a structure in which at least a weather resistant substrate (DS) and a gas barrier substrate (GS) are laminated,
The gas barrier base material (GS) is Ri Do a laminate comprising plus plastic film layer and the (S) a soft deposition primer layer (P) and a hard deposited primer layer (H) and deposited layer and (V),
The soft deposition primer layer (P) is composed of a compound containing at least the following components (P1), (P2) and (P3):
The primer layer for hard vapor deposition (H) is composed of a compound containing at least the following component (H1) and one or both of (H2) and (H3):
The mass ratio (P1) / (P3) is in the range of 99/1 to 50/50, and the mass ratio {(P1) + (P3)} / (P2) is in the range of 100/5 to 100/100. A sheet for sealing the back surface of a solar cell.
(P1): Amorphous polyester polyol having a glass transition temperature of less than 40 ° C., an isocyanate extension product thereof, or a mixture thereof.
(P2): at least one crosslinking agent selected from an isocyanate compound, a carbodiimide compound, a transition metal compound represented by the general formula M (OR ′) _n , and a phosphorus compound [wherein R ′ is an alkyl group M is a metal ion and n is the valence of the ion. ].
(P3): a polyol that is incompatible with (P1) and has a glass transition temperature of 40 ° C. or higher, an isocyanate extension of this polyol, or a mixture thereof.
(H1): Polyester polyol having a glass transition temperature of 40 ° C. or higher, an isocyanate extension product thereof, an acrylic polyol or an isocyanate extension product thereof, a carbonate polyol or an isocyanate extension product thereof, or a mixture thereof (note that an acrylic polyol or a carbonate polyol is used) When used, (P3) and (H1) may be the same).
(H2): at least one cross-linking agent selected from an isocyanate compound, a carbodiimide compound, a transition metal compound represented by the general formula M (OR ′) _n , and a phosphorus compound [where R ′ is an alkyl group M is a metal ion and n is the valence of the ion. ].
(H3): an organosilane represented by the general formula R—Si (OR ′) ₃ or a hydrolyzate thereof, one or more metal alkoxides represented by the general formula M (OR ′) _n or a hydrolyzate thereof, Or a mixture thereof [wherein R is a functional group selected from an alkyl group, a (meth) acryloyl group, a vinyl group, an amino group, an epoxy group, and an isocyanate group, R ′ is an alkyl group, and M is a metal ion. And n is the valence of the ion. ]. 2. The solar cell back surface sealing sheet according to claim 1 , wherein the polyol of (P3) comprises an acrylic polyol, a carbonate polyol, or a mixture thereof. The deposition layer (V) is a silicon oxide having a thickness of 5 to 300 nm, aluminum oxide, according to claim 1 or 2, characterized in that it consists of at least one kind of inorganic oxide selected from magnesium oxide Solar cell back surface sealing sheet. The gas barrier substrate (GS) further includes a deposition overcoat layer (O) laminated on the deposition layer (V),
The solar cell back surface sealing according to any one of claims 1 to 3 , wherein the deposition overcoat layer (O) is made of a compound containing the following components (O1) and (O2). Sheet.
(O1): Water-soluble polymer.
(O2): an organosilane represented by the general formula R—Si (OR ′) ₃ or a hydrolyzate thereof, one or more metal alkoxides represented by the general formula M (OR ′) _n or a hydrolyzate thereof, Phosphorus compounds, or a mixture thereof [wherein R is a functional group selected from an alkyl group, a (meth) acryloyl group, a vinyl group, an amino group, an epoxy group, an isocyanate group, R ′ is an alkyl group, etc. M is a metal ion, and n is the valence of the ion. ]. The solar cell module using the sheet | seat for solar cell backside sealing as described in any one of Claims 1-4 .

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