JP6660037B2 - Solar cell module - Google Patents

Description

  The present invention relates to a solar cell module.

  2. Description of the Related Art In recent years, solar cells have been attracting attention as a clean energy source due to increasing awareness of environmental issues. At present, various types of solar cell modules have been developed and proposed. Generally, a solar cell module has a configuration in which a transparent front substrate made of glass or the like, a solar cell element, and a back surface protection sheet are laminated via a sealing material sheet.

  Conventionally, as a sealing material sheet for a solar cell module, a sheet using EVA (ethylene-vinyl acetate copolymer) as a base resin, which is excellent in transparency, adhesion, and the like, has been widely used. However, in recent years, the development of a sealing material sheet using a polyethylene resin as a base resin having transparency equivalent to EVA and excellent in hydrolysis resistance and the like as compared with EVA is progressing.

  Here, in general, a solar cell element has high spectral sensitivity to light in a wavelength region from visible light to near infrared light. Therefore, by arranging a wavelength conversion layer containing a wavelength conversion agent for converting ultraviolet light into visible light in the solar cell module, the use efficiency of sunlight in the solar cell element is increased, and the power generation efficiency is improved. A solar cell module has been proposed (see Patent Document 1).

  Also, in order to exhibit the wavelength conversion function and the protective function of the sealing material sheet in a well-balanced manner, a multi-layered sealing structure in which other functional layers such as a protective layer are laminated on both surfaces of the wavelength conversion layer. A stop sheet has also been proposed (see Patent Document 2).

As a wavelength converter added to a sealing material sheet for a solar cell module and used, a wavelength converter made of an inorganic phosphor such as, for example, MgF ₂ : Eu ²⁺ has been widely used (Patent Document 3). reference).

  However, when a wavelength conversion agent is added to a sealing material sheet using the above-mentioned polyethylene resin as a base resin, the inorganic wavelength conversion agent as described above has poor compatibility with an olefin, and the sealing material There has been a problem that the optical characteristics of the sheet tend to be reduced. In this regard, it has been clarified that it is desirable to select an organic wavelength converting agent such as triazole as a wavelength converting agent to be added to a sealing material sheet using a polyethylene resin as a base resin.

JP 2007-27271 A JP 2012-15205 A JP 2012-15205 A JP 2012-044153 A

  In the case where a wavelength converter is added to an encapsulant sheet based on a polyethylene resin, which is increasing in demand in place of EVA encapsulant in recent years, as described above, by selecting an organic wavelength converter, The optical properties in the early stage after production can be better maintained than when an inorganic wavelength conversion agent is selected.

  However, the organic wavelength conversion agent has a problem in weather resistance at the time of long-term use in a high-temperature and high-humidity environment supposed as the actual use environment of the solar cell module, and after long-term use in the harsh environment described above. It has been recognized that a further problem is that the quantum yield of the wavelength conversion agent may be reduced and the wavelength conversion function may be significantly deteriorated.

  Here, a radical absorber is appropriately used in the sealing material sheet for the solar cell module from the viewpoint of improving weather resistance. It is presumed that the addition of the radical absorber is also effective for the deterioration of the wavelength converter. As a radical absorber, a hindered amine light stabilizer (HALS) is known. For example, Patent Literature 4 describes using a so-called high molecular weight type hindered amine light stabilizer as HALS.

  A hindered amine light stabilizer of a high molecular weight type having a molecular weight of 1000 or more generally has excellent migration resistance and elution resistance. However, long-term migration differs depending on the type, and as a result, the haze decreases, especially Therefore, it is important to select a HALS that can suppress the increase in haze. On the other hand, the sealing material sheet is required to have long-term durability in terms of adhesion to a glass substrate, but there is still a reality that the effect of long-term glass adhesion differs depending on the type of HALS. As described above, the sealing material sheet is required to have both haze increase suppression and long-term glass adhesion, but the presence of HALS is a factor that reduces both of them.

  The present invention has been made in view of the above circumstances, and is based on a polyethylene resin having excellent hydrolysis resistance and the like as a base resin, and a sealing material sheet having a wavelength conversion function (hereinafter, referred to as “wavelength conversion type sealing”). Material sheet), which can maintain good optical characteristics and wavelength conversion function even after long-term use in a high-temperature and high-humidity environment, that is, excellent weather resistance. It is an object of the present invention to provide a solar cell module using a wavelength conversion type sealing material sheet having properties and durability.

  The present inventors have conducted intensive studies and found that the encapsulant sheet was a multilayer sheet, and only the intermediate layer thereof was added with an organic wavelength converter having a molecular weight larger than a specific value, thereby obtaining a wavelength converter. Bleed-out due to the time-dependent change of the Further, in such a sealing material sheet, it has been found that the above problems can be solved by selectively using HALS, which is more effective in radical absorption, and by adding an appropriate amount to each layer, to complete the present invention. Reached. More specifically, the present invention provides the following.

(1) From the light receiving surface side of the incident light, a transparent front substrate, a sealing material sheet for the light receiving surface side, a solar cell element, a sealing material sheet for the non-light receiving surface side, and a back surface protection sheet are sequentially laminated. In the solar cell module, the light-receiving surface side sealing material sheet is a multilayer sheet including an intermediate layer and outermost layers disposed on both surfaces thereof, wherein the intermediate layer and the outermost layer are , and density of 0.870 g / cm ³ or more 0.970 g / cm ³ or less of low density polyethylene base resin, wherein the intermediate layer contains an organic wavelength converting material, wherein the outermost layer, the organic wavelength converting agent When is contained, the content ratio is smaller than the content ratio of the organic wavelength converting agent in the intermediate layer, the intermediate layer and the outermost layer contain a hindered amine light stabilizer, The hindered amine-based Koyasu Among the agents, a hindered amine light stabilizer having a mass ratio of 1/2 or more is a sealing material sheet as the following light stabilizer (A), and the sealing material sheet for the non-light receiving surface side is polyethylene. A solar cell module, which is a white sealing material sheet.
Light stabilizer (A): a hindered amine light stabilizer having three or more piperidine rings in the side chain of the monomer unit and having a molecular weight of 1,000 to 10,000.

  (2) The content of the light stabilizer (A) in the intermediate layer and the outermost layer of the encapsulant sheet for the light-receiving surface is 0.1% by mass or more and 0.5% by mass or less (1 ).

  (3) The solar cell module according to (1) or (2), wherein the organic wavelength conversion agent is a wavelength conversion agent having a number average molecular weight of 100 or more and 1000 or less.

(4) The solar cell module according to any one of (1) to (3), wherein the organic wavelength conversion agent is a derivative of any one of pyrazine, pyridine, and triazole or a mixture thereof.
(5) The content ratio of the organic wavelength converting agent in the outermost layer is not more than の of the content ratio of the organic wavelength converting agent in the intermediate layer (1) to (4). The solar cell module according to any one of the above.

  (6) The solar cell module according to any one of (1) to (5), wherein the outermost layer further contains a silane-modified polyethylene-based resin.

  According to the present invention, it is possible to provide a solar cell module using a sealing material sheet of a wavelength conversion type, which is a sealing material sheet using a polyethylene resin as a base resin and has excellent long-term weather resistance. it can.

It is a cross section showing an example of layer composition of a sealant sheet of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS It is a cross-sectional schematic diagram which shows an example of the layer structure of the sealing material sheet of this invention, and the solar cell module using the same.

  Hereinafter, first, a sealing material composition (hereinafter, also simply referred to as “sealing material composition”) that can be preferably used for the sealing material sheet for a solar cell module of the present invention, and a sealing for a solar cell module. A material sheet (hereinafter, also simply referred to as a “sealing material sheet”) and a manufacturing method thereof, and a solar cell module using the sealing material sheet of the present invention and a manufacturing method thereof will be sequentially described. In this specification, a multilayer sealing material sheet is a sealing material having a multilayer structure including an outermost layer formed on both surfaces of the sealing material sheet and an intermediate layer other than the outermost layer. It refers to a sheet. The intermediate layer refers to a layer other than the outermost layer, and may have a single-layer structure, or may have a multilayer structure including a plurality of layers.

<Sealant composition>
The sealing material sheet of the present invention is a multilayer sealing material sheet including an intermediate layer and an outermost layer. And the sealing material composition for intermediate layers for forming the intermediate layer of the multilayer sealing material sheet contains a wavelength conversion agent as an essential component. The sealing material composition for the outermost layer for forming the outermost layer is also based on a low-density polyethylene resin, but does not contain a wavelength converter unlike the sealing material composition for the intermediate layer. The sealing material composition for the intermediate layer and the sealing material composition for the outermost layer have a specific HALS selected as an essential component by focusing on the radical absorbing ability.

[Sealant composition for intermediate layer]
The sealing material composition for the intermediate layer is a sealing material composition used for forming the intermediate layer of the multilayer sealing material sheet of the present invention. The sealing material composition for the intermediate layer contains, as essential components, an intermediate layer base resin made of a polyethylene resin and an organic wavelength conversion agent.

(Base resin)
As the polyethylene resin used as a base resin of the sealing material composition for the intermediate layer (hereinafter also referred to as “base resin for the intermediate layer”), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), or metallocene Linear low-density polyethylene (M-LLDPE) can be preferably used.

Density polyethylene resin used as the intermediate layer base resin, 0.870 g / cm ³ or more 0.970 g / cm ³ or less, or preferably 0.870 g / cm ³ or more 0.930 g / cm ³ or less. The density of the intermediate layer base resin is preferably higher than that of the outermost layer base resin described later in detail. By setting the density of the intermediate layer base resin within the above range, the heat resistance of the sealing material sheet can be sufficiently improved while maintaining the molding characteristics and the protection performance of the solar cell element.

  Further, the base resin for the intermediate layer is preferably a polyethylene resin in which the number of full double bonds remaining in the composition stage is relatively larger than the number of full double bonds of the base resin for the outermost layer. . Further, the total number of double bonds in the base resin for the intermediate layer is preferably 0.5 or more and 4.0 or less, more preferably 1.0 or more and 4.0 or less. By setting the total number of double bonds in the sealing material composition for the intermediate layer to the above range, when performing crosslinking by irradiation with ionizing radiation, the crosslinking is sufficiently advanced to improve the heat resistance of the sealing material sheet. It can be improved sufficiently. On the other hand, even if the crosslinking of the intermediate layer by irradiation with ionizing radiation is sufficiently advanced, the number of full double bonds in the sealing material composition for the outermost layer is in a range different from that of the sealing material composition for the intermediate layer. By limiting to, the cross-linking progress of the outermost layer is suppressed in a mode different from that of the intermediate layer, and as a result, favorable molding characteristics can be maintained as the whole sealing material sheet. When the number of full double bonds in the sealing material composition for the intermediate layer is less than 0.5, the heat resistance of the sealing material sheet is not sufficiently improved. On the other hand, when the number exceeds 4.0, molding properties and adhesion are undesirably reduced due to excessive crosslinking.

Here, the “number of full double bonds” in the present specification refers to the sheet density d (g / cm ³ ), the sheet thickness t (cm), and the absorption band of the infrared absorption spectrum of the sealing material composition in a sheet state. Is a value obtained by the following equation from the absorbance A of The measurement of the absorbance A in the absorption band of the infrared absorption spectrum was performed by NICOLET 6700 manufactured by Thermo Scientific.
Number of terminal vinyl groups = 0.231 / (d × t) × A (910 cm ⁻¹ )
Number of vinylidene groups = 0.271 / (d × t) × A (888 cm ⁻¹ )
Number of trans vinylene groups = 0.328 / (d × t) × A (965 cm ⁻¹ )
The total number of double bonds = the number of terminal vinyl groups + the number of vinylidene groups + the number of transvinylene groups The total number of double bonds per 2,000 carbons according to the above method.

  The content of the base resin contained in the encapsulant composition for the intermediate layer is preferably 10 parts by mass or more and 99 parts by mass based on 100 parts by mass of all resin components in the encapsulant composition for the intermediate layer. It is at most 50 parts by mass and at most 99 parts by mass, further preferably at least 90 parts by mass and at most 99 parts by mass. The sealing material composition for the intermediate layer may include another resin within the above range. These may be used, for example, as a resin for addition, or may be used to make a masterbatch of other components described below. In this specification, the term “all resin components” includes the other resins described above.

(Organic wavelength converter)
The wavelength conversion agent contributes to the improvement of the power generation efficiency of the solar cell module by converting the light in the wavelength region having low absorption sensitivity into the wavelength region having high absorption sensitivity in the solar cell element and causing the light to enter the solar cell element. Say things. Various inorganic, organic, or hybrid wavelength converters are known.

  Among these, an organic wavelength conversion agent is used for the sealing material composition for the intermediate layer of the sealing material sheet of the present invention. Among these organic wavelength converting agents, those having a number average molecular weight of 100 or more and 1000 or less can be particularly preferably used. By adding the organic wavelength converting agent to only the intermediate layer in the multilayer sheet, the leaching of the organic wavelength converting agent to the outermost layer side of the sealing material sheet is suppressed, and the initial stage of the manufacturing of the sealing material sheet is suppressed. The optical characteristics can be made sufficiently favorable. However, with respect to the organic wavelength conversion agent, by selecting only an agent having a relatively large molecular weight and a number average molecular weight of 100 or more, even after a long-term use period under severe conditions of high temperature and high humidity, the organic wavelength conversion agent can be used. Leaching of the conversion agent to the outermost layer side can be extremely suppressed, and deterioration of the optical properties and adhesion of the sealing material sheet due to bleed out of the wavelength conversion agent can be avoided.

  As the organic wavelength conversion agent, a conventionally known agent can be used without any particular limitation. However, it is more preferable to select one having the above molecular weight range. Specifically, pyrazine derivatives, pyridine derivatives, triazole derivatives, benzoxazoyl derivatives, coumarin derivatives, styrene biphenyl derivatives, pyrazolone derivatives, bis (triazinylamino) stilbendisulfonic acid derivatives, bisstyrylbiphenyl derivatives, bisbenzooxazolylthiophenes Derivatives, perylene derivatives, pyrene derivatives, pentacene derivatives, fluorescein derivatives, rhodamine derivatives, acridine derivatives, benzimidazole derivatives, flavone derivatives and the like. Among these, in particular, any one derivative of pyrazine, pyridine, and triazole or a mixture thereof can be preferably used. For example, a low molecular weight organic wavelength converting agent having a number average molecular weight of less than 100, such as a wavelength converting agent composed of a simple substance of triazole, can be used satisfactorily. It is more advantageous in long-term weather resistance under a severe environment of high temperature and humidity.

  The addition amount of these organic wavelength converting agents to the sealing material composition for the intermediate layer is 0.05% by mass or more and 0.5% by mass or less, preferably 0.1% by mass or more and 0.4% by mass. The following may be sufficient. Within this range, an optimal amount may be appropriately added according to the light emission intensity and quantum yield of each material, the thickness of each layer of the sealing material sheet, and the like. If the amount of the organic wavelength converter is less than 0.05% by mass, the wavelength cannot be sufficiently converted, so that the power generation efficiency of the solar cell module cannot be sufficiently increased. On the other hand, when the addition amount of the organic wavelength converting agent is more than 0.5% by mass, it is possible to sufficiently avoid the leaching of the wavelength converting agent into the outermost layer and the deterioration of the optical properties of the sealing material sheet due to bleed out. It is not preferable because it may not be possible.

  As described above, after limiting the organic wavelength conversion agent to be added to the sealing material composition for the intermediate layer to those having a certain molecular weight or more, in this way, only the composition for the intermediate layer has an appropriate amount. By adding in the range, the leaching of the wavelength conversion agent from the intermediate layer to the outermost layer side after the formation of the sealing material sheet can be sufficiently suppressed. And a wavelength conversion type sealing material sheet capable of exhibiting a preferable wavelength conversion function while preventing a decrease in adhesion due to a decrease in fluidity of the outermost layer and a deterioration in optical characteristics due to bleed out of the wavelength conversion agent. can do.

(Hindered amine light stabilizer (HALS))
The encapsulant composition for the intermediate layer of the encapsulant sheet of the present invention uses the following light stabilizer (A) as a hindered amine-based light stabilizer, or comprises the following light stabilizer (A) and Characterized in that it is used in combination with a light stabilizer (B). The light stabilizer (A) and the light stabilizer (B) are both high molecular weight types having a molecular weight of 1,000 or more. It is preferable that these light stabilizers ((A) and (B)) are also added to the sealing material composition for the outermost layer, similarly to the composition for the intermediate layer.
Light stabilizer (A): a hindered amine light stabilizer having a molecular weight of 1,000 or more and 10,000 or less having three or more piperidine rings in the side chain of the monomer unit. Light stabilizer (B): having a piperidine ring in the main chain of the monomer unit. Hindered amine light stabilizer having a molecular weight of 1,000 or more and 5,000 or less having only one

  The light stabilizer (A) is a hindered amine light stabilizer having three or more piperidine rings in a monomer unit and having a molecular weight of 1,000 to 10,000, and preferably dibutylamine-1,3,5-triazine-N, N A polycondensate of '-bis (2,2,6,6-tetramethyl-4-piperidyl-1,6-hexamethylenediamine-N- (2,2,6,6-tetramemethyl-4-piperidyl) butylamine This compound is commercially available as Chimassorb 2020 and has a CAS number of 192268-64-7 with a molecular weight of 2600 to 3400 and a melting point of 130 ° C to 136 ° C.

  The light stabilizer (B) is a compound commercially available as KEMISTAB62, and is 1- [2- (4-hydroxy-2,2,6,6-tetramethylpiperidino) ethyl butanedioate], CAS No. 65447-77-0. It has only one piperidine ring in the main chain of the monomer unit, has a molecular weight of 3100 to 4000, and has a melting point of 55 ° C to 70 ° C, and is known as HALS for polyolefin applications.

  Even if a high-molecular-weight type HALS is blended in a large amount, the HALS has poor glass adhesion properties, and the initial glass adhesion strength decreases. For this reason, in order to improve the initial glass adhesion strength, it is necessary to considerably reduce the blending amount, specifically, to be 1% or less, more preferably 0.5% or less in the sealing material sheet. However, with this amount, the radical absorbing ability becomes insufficient.

  Here, among various high molecular weight types of HALS, according to the knowledge newly obtained by the present inventors, the light stabilizer (A) has three or more piperidine rings in the side chain of the monomer unit. It is extremely excellent in radical trap absorption capacity. Therefore, it is extremely excellent from the viewpoint of suppressing the deterioration with time of the haze and the long-term glass adhesion. Therefore, in the production method of the present invention, this light stabilizer (A) is selectively used as a main light stabilizer.

  On the other hand, the light stabilizer (B) has a small content dependency of the initial glass adhesion strength, and the initial glass adhesion strength does not decrease even if the content is about 0.5% by mass or more in the sealing material sheet. There are features. However, when the light stabilizer (B) is used alone, there is a problem that the haze increases with time, and it has been found that the haze increases with time even if the content is reduced. The reason for this is considered to be HALS aggregation or blooming. In addition, the long-term glass adhesion also tends to slightly decrease.

  As described above, the light stabilizer (B) has advantages and disadvantages. However, in the present invention, by using the light stabilizer (A) and the light stabilizer (B) together, the haze increase suppression and the long-term glass adhesion are more improved. A high level of compatibility was made possible. Incidentally, the haze in the present invention means a value measured by the measuring method in the embodiment, and means a value including a haze on one side measured in a state where the glass is adhered.

  The preferable content of the light stabilizer (A) and the light stabilizer (B) is 0.01% by mass or more and 1.0% by mass or less, more preferably 0.1% by mass or less in the sealing material sheet in total of both agents. It is at least 0.5% by mass. The mixing ratio when both are used is not particularly limited, but is preferably about 1: 1.

(Cross-linking aid)
The sealing material composition for the intermediate layer preferably further contains a crosslinking aid. As a crosslinking assistant, a polyfunctional monomer having a carbon-carbon double bond and an epoxy group can be preferably used. More preferably, the cross-linking aid is one in which the functional group of the polyfunctional monomer is an allyl group, a (meth) acrylate group, or a vinyl group. By adding such a crosslinking aid, the crystallinity of the low-density polyethylene is reduced, and a sealing material sheet having excellent low-temperature flexibility can be obtained.

  Specifically, polyallyl compounds such as triallyl isocyanurate (TAIC), triallyl cyanurate, diallyl phthalate, diallyl fumarate, and diallyl maleate; trimethylolpropane trimethacrylate (TMPT); and trimethylolpropane triacrylate (TMPTA) , Such as ethylene glycol diacrylate, ethylene glycol dimethacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, 1,9-nonanediol diacrylate, and tricyclodecane dimethanol diacrylate. ) Acryloxy compounds, glycidyl methacrylate containing a double bond and an epoxy group, 4-hydroxybutyl acrylate glycidyl ether, and 1,2 or more containing two or more epoxy groups. - hexanediol diglycidyl ether, and 1,4-butanediol diglycidyl ether, cyclohexanedimethanol diglycidyl ether, an epoxy-based compounds such as trimethylolpropane polyglycidyl ether. These may be used alone or in combination of two or more.

  Among the above, tricyclodecane dimethanol diacrylate, which has a particularly high effect of improving the adhesion to the glass surface, has good compatibility with low-density polyethylene, and can be expected to improve heat resistance, can be particularly preferably used. The content of the crosslinking assistant is preferably 0.01 to 3 parts by mass, more preferably 0 to 3 parts by mass, based on 100 parts by mass of all resin components of the encapsulant composition for the outer layer. The range is from 0.05 part by mass to 2.0 parts by mass. By providing a multilayer sheet structure in which the crosslinking assistant is contained only in the intermediate layer, while maintaining the adhesion and molding properties of the sealing material sheet in a preferable range, at the same time, impart sufficient heat resistance to the sealing material sheet. be able to.

  In the production method of the present invention, it is preferable that the crosslinking aid is not added to the sealing material composition for the outermost layer. This is because, when a crosslinking aid is added to the sealing material composition for the outermost layer, the risk of a decrease in adhesion due to a decrease in fluidity and a so-called bleed-out of the crosslinking aid increases.

[Encapsulant composition for outermost layer]
The encapsulant composition for the outermost layer is an encapsulant composition used for molding the outermost layers formed on both outermost surfaces of the multilayer encapsulant sheet of the present invention. The encapsulant composition for the outermost layer is a base resin composed of a polyethylene resin, and preferably contains an adhesive copolymer resin such as a silane-modified polyethylene resin.

(Base resin)
As the polyethylene resin used as the base resin of the encapsulant composition for the outermost layer (hereinafter also referred to as “base resin for the outermost layer”), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), or Metallocene linear low-density polyethylene (M-LLDPE) can be preferably used as appropriate.

Density of the polyethylene resin used as the base resin for the outermost layer, 0.870 g / cm ³ or more 0.970 g / cm ³ or less, preferably 0.870 g / cm ³ or more 0.930 g / cm ³ or less. The density of the base resin for the outermost layer is preferably lower than that of the base resin of the sealing material composition for the intermediate layer. More specifically, the density of the outermost layer base resin is preferably 93% or more and 99% or less of the density of the intermediate layer base resin. By setting the density of the base resin for the outermost layer within the above range, it is possible to impart sufficient adhesion and molding characteristics while maintaining the protection performance of the solar cell element. From the viewpoint of imparting molding characteristics, the lower the density of the outermost layer is, the better. However, by maintaining the density of the intermediate layer at 93% or more, the excess of the organic wavelength converting agent from the intermediate layer to the outermost layer can be obtained. Leaching can be suppressed.

  As the base resin for the outermost layer, it is preferable to use a polyethylene resin in which the number of full double bonds remaining in the composition stage is relatively smaller than the number of full double bonds of the base resin for the intermediate layer. Further, the number of full double bonds of the polyethylene resin as the base resin for the outermost layer is preferably 0 or more and 1.0 or less, more preferably 0 or more and 0.5 or less.

(Silane-modified polyethylene resin)
The sealing material composition for the outermost layer preferably contains a silane-modified polyethylene-based resin in addition to the base resin. The silane-modified polyethylene resin is a resin obtained by graft-polymerizing a low-density polyethylene serving as a main chain, preferably a linear low-density polyethylene, with an ethylenically unsaturated silane compound as a side chain. Since such a graft copolymer has a high degree of freedom of silanol groups that contribute to the adhesive force, it is possible to improve the adhesion of the sealing material sheet to other members in the solar cell module. In this specification, the silane-modified polyethylene-based resin refers to, for example, a silane-modified polyethylene-based resin that can be produced by the following production method, and is at least a part of a linear low-density polyethylene resin serving as a main chain. Is a concept indicating a resin obtained by graft polymerization with an ethylenically unsaturated silane compound. The resin as a main chain of the above, as with the base resin, it is preferred that the density 0.870 g / cm ³ or more 0.900 g / cm ³ or less of the polyethylene resin.

The silane-modified polyethylene-based resin can be produced by the following method, for example, as described in JP-A-2003-46105. For example, one or more α-olefins, one or more ethylenically unsaturated silane compounds, and if necessary, one or more other unsaturated monomers, Using a reaction vessel, for example, a pressure of 500 kg / cm ² or more and 4000 kg / cm ² or less, preferably 1000 kg / cm ² or more and 4000 kg / cm ² or less, temperature, 100 ° C. or more and 400 ° C. or less, preferably 150 kg / cm ² or less Under the condition of not less than 350 ° C. and not more than 350 ° C., random copolymerization is carried out simultaneously or stepwise in the presence of a radical polymerization initiator and, if necessary, a chain transfer agent, and further produced by the copolymerization. By modifying or condensing a portion of the silane compound constituting the random copolymer, a silane-modified polyethylene-based resin can be produced.

  As the polyethylene resin of the main chain, it is preferable to use linear low-density polyethylene which is an ethylene-α-olefin copolymer, and it is more preferable to use metallocene linear low-density polyethylene. Metallocene linear low-density polyethylene is synthesized using a metallocene catalyst that is a single-site catalyst. Such polyethylene has few side chains and uniform distribution of comonomer. For this reason, the molecular weight distribution is narrow, it is possible to make the above ultra-low density, and flexibility can be given to the sealing material sheet. As a result of imparting flexibility to the sealing material sheet, the adhesion between the sealing material sheet and a transparent front substrate such as glass can be improved.

  As the α-olefin of the linear low-density polyethylene, an α-olefin having no branch is preferably used. Among them, 1-hexene and 1-heptene, which are α-olefins having 6 to 8 carbon atoms, are preferred. Or 1-octene is particularly preferably used. When the carbon number of the α-olefin is 6 or more and 8 or less, good flexibility and good strength can be provided to the sealing material sheet. As a result, the adhesion between the sealing material sheet and the transparent front substrate such as glass is further increased.

  As an ethylenically unsaturated silane compound to be graft-polymerized with linear low-density polyethylene, for example, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltripropoxysilane, vinyltriisopropoxysilane, vinyltributoxysilane, vinyltripentyloxysilane Use one or more selected from vinyltriphenoxysilane, vinyltribenzyloxysilane, vinyltrimethylenedioxysilane, vinyltriethylenedioxysilane, vinylpropionyloxysilane, vinyltriacetoxysilane, and vinyltricarboxysilane be able to.

  The graft amount, which is the content of the ethylenically unsaturated silane compound in the silane-modified polyethylene-based resin, is 0.001% by mass or more and 15% by mass or less, preferably 0.01% by mass or less, based on the content of the silane-modified polyethylene-based resin in the base resin. The amount may be appropriately adjusted so as to be from 5% by mass to 5% by mass, particularly preferably from 0.05% by mass to 2% by mass. In the present invention, when the content of the ethylenically unsaturated silane compound is large, the mechanical strength and the heat resistance are excellent, but when the content is excessive, the tensile elongation and the heat fusion property tend to be inferior.

  The content of the silane-modified polyethylene-based resin in the encapsulant composition for the outermost layer used in the encapsulant composition for the outermost layer of the encapsulant sheet of the present invention is 8% by mass or more and 45% by mass or less. Is preferred. In the present invention, when the content of the silane-modified polyethylene-based resin is 8% by mass or more, mechanical strength and heat resistance are excellent, but when the content is excessive, tensile elongation and heat-fusibility tend to be poor. It is in.

  By using the silane-modified polyethylene resin described above as a component of the encapsulant composition for the outermost layer of the encapsulant composition for a solar cell module, the adhesiveness, strength, durability and the like are excellent. In addition, a sealing material sheet having excellent weather resistance, heat resistance, water resistance, light resistance, wind pressure resistance, hail resistance, and other various properties can be obtained. By using a silane-modified polyethylene-based resin, various effects can be obtained in this way, but in particular, without being affected by manufacturing conditions such as thermocompression bonding for manufacturing a solar cell module, the sealing material sheet is extremely A general advantage is that excellent heat fusion, that is, excellent adhesion to a glass substrate or the like constituting a solar cell module can be imparted.

  Further, by adding the silane-modified polyethylene resin to the outermost layer of the encapsulant sheet of the present invention, it is possible to further suppress (bleed out) of the wavelength conversion agent as well as the above general advantages. The effects unique to the present invention are also exhibited. Suppression of this bleed-out is caused by the fact that the silane-modified polyethylene-based resin does not stay inside the outermost layer, but aggregates at the interface with the glass or the solar cell element constituting the transparent front substrate to form a Si—O—Si bond. This is presumed to be the effect of delaying the transfer of the wavelength conversion agent to the surface of the sealing material sheet. From the viewpoint of the effects specific to the present invention, the addition of the silane-modified polyethylene resin to the outermost layer is preferable.

(Hindered amine light stabilizer (HALS))
In the encapsulant composition for the outermost layer, in addition to the base resin, as the hindered amine-based light stabilizer, the light stabilizer (A) alone or the light stabilizer (A) and the light stabilizer (B) are used. Is preferably used in combination with the above-described compound in the intermediate layer.

[Other additives]
In each of the sealing material compositions for the intermediate layer and the outermost layer, any of the following additives can be appropriately contained as needed.

(Crosslinking agent)
Each of the sealing material compositions for the intermediate layer and the outermost layer may contain a necessary minimum amount of a crosslinking agent, but it is more preferable that the crosslinking agent is not added to any of the layers. While the addition of the crosslinking aid to the above-mentioned intermediate layer allows a sufficiently appropriate crosslinking to proceed, the addition of a crosslinking agent such as an organic peroxide separately requires integration of the solar cell module. During the thermal lamination process, the risk of problems such as foaming due to degass increases. When adding a cross-linking agent, a known one can be used and is not particularly limited. For example, a known radical polymerization initiator can be used.

  When a crosslinking agent is added, the content thereof is preferably 0% by mass or more and 0.5% by mass or less in the sealing material composition for the intermediate layer and the outermost layer, and more preferably 0% by mass or less. The range is from 0.02% by mass to 0.5% by mass. If the amount of the crosslinking agent exceeds 0.5% by mass, the progress of crosslinking in the crosslinking step becomes excessive, and the molding characteristics become insufficient, which is not preferable.

(Adhesion improver)
The adhesion durability to other base materials can be further increased by appropriately adding an adhesion improver to each of the sealing material compositions for the intermediate layer and the outermost layer. As the adhesion improver, a known silane coupling agent can be used. The silane coupling agent is not particularly limited. For example, vinyl silane coupling agents such as vinyltrichlorosilane, vinyltrimethoxysilane, and vinyltriethoxysilane, 3-methacryloxypropyltrimethoxysilane, and 3-methacryloxypropyldiethoxy Methacryloxy silane coupling agents such as silane and 3-methacryloxypropyltriethoxysilane can be preferably used. These can be used alone or in combination of two or more.

  When a silane coupling agent is added as an adhesion improver, its content is 0.1% by mass or more and 10.0% by mass or less in the sealing material composition, and the upper limit is preferably 5.0% by mass. It is as follows. When the content of the silane coupling agent is within the above range, and the polyolefin-based resin constituting the encapsulant composition contains an appropriate amount of the ethylenically unsaturated silane compound, the adhesiveness falls within a more preferable range. And improve. It is to be noted that exceeding this range is not preferred because the film-forming properties may be reduced and the silane coupling agent may bleed out.

(Other components)
Each of the sealing material compositions for the intermediate layer and the outermost layer may further contain other components. For example, components such as various fillers, ultraviolet absorbers, and heat stabilizers are exemplified. These contents vary depending on the particle shape, density and the like, but are preferably in the range of 0.001% by mass or more and 5% by mass or less with respect to each sealing material composition. By including these additives, it is possible to provide the sealing material sheet with stable mechanical strength over a long period of time and an effect of preventing yellowing, cracking, and the like.

<Sealant sheet>
The sealing material sheet of the present invention is a multilayer sealing material sheet including an intermediate layer and outermost layers disposed on both surfaces of the intermediate layer. Then, the above-mentioned organic wavelength converting agent, preferably in a specific molecular weight range, is added only to the intermediate layer, and further, the above-mentioned specific one or two types of HALS are selected for the intermediate layer and the outermost layer. In an appropriate amount.

  Incidentally, the content ratio of the wavelength converting agent in the outermost layer after film formation is smaller than the content ratio of the wavelength converting agent in the intermediate layer, at least immediately after film formation, the wavelength converting agent in the intermediate layer. It is suppressed to １ ／ or less of the content ratio. More specifically, the content of the wavelength converting agent in the intermediate layer in the sealing material sheet after film formation is in the range of 0.05% by mass or more and 0.5% by mass or less, and the wavelength conversion agent in the outermost layer is The content of the agent is in the range of 0% by mass to 0.25% by mass.

  The content of the wavelength converting agent in the outermost layer may be 0%, or within the above range, a part of the organic wavelength converting agent leached from the intermediate layer may be included. When the content is within the above range, even if the wavelength conversion agent has penetrated into the outermost layer, the initial optical properties and adhesion of the sealing material sheet can be kept in a sufficiently preferable range. Hereinafter, as a preferred embodiment of the present invention, a three-layer sealing material sheet 1 in which a total of two outermost layers are laminated on the front and back of an intermediate layer which is a single layer will be described with reference to FIG. I do.

  The sealing material sheet 1 has an intermediate layer 11, and outermost layers 12 are arranged on both surfaces of the intermediate layer 11. However, even if it is a sealing material sheet in which the intermediate layer itself has a multilayer structure and other functional layers are arranged in the intermediate layer, the intermediate layer and the outermost layer having the constitutional requirements of the present invention are provided, and The present invention is within the scope of the present invention as long as it is a sealing material sheet having the other components of the present invention.

  The intermediate layer 11 is a layer constituting a main part as a substrate layer in the sealing material sheet 1. Further, the intermediate layer 11 is also a wavelength conversion layer that imparts a wavelength conversion function to the sealing material sheet 1 by containing a wavelength conversion agent. It is preferable that the intermediate layer 11 has been subjected to a crosslinking treatment for the purpose of improving heat resistance, such as a treatment in which an appropriate amount of a crosslinking aid is added and irradiation with ionizing radiation is performed. Thereby, the weather resistance and durability of the solar cell module can be further improved.

  The outermost layer 12 is a layer disposed on the outermost surface of the sealing material sheet in the sealing material sheet 1 and constituting a subordinate portion as a surface material. The outermost layer 12 is a layer mainly exhibiting the effect of improving the adhesion as a solar cell module and the molding characteristics during the integration step.

  The sealing material sheet 1 is formed by laminating resin sheets for respective layers having different superior physical properties and special functions in an optimal arrangement to form a multilayer sheet. It is a wavelength conversion type sealing material sheet made of a polyethylene resin having a high water vapor barrier property and having an excellent balance of heat resistance, adhesion and molding properties.

  The total thickness of the sealing material sheet 1 including the intermediate layer 11 and the outermost layer 12 is preferably from 100 μm to 1000 μm, and more preferably from 200 μm to 600 μm. If it is less than 100 μm, the impact cannot be sufficiently reduced, and if it exceeds 1000 μm, no further effect can be obtained and it is uneconomical. Further, the encapsulant sheet of the present invention has a flexibility in the outermost layer and a heat resistance in the intermediate layer, thereby suppressing run-out and a change in film thickness during the laminating process, to be about 500 μm or less. Even when the film is thinned, it is possible to obtain sufficiently favorable molding properties, heat resistance, and protection performance of the solar cell element.

  About the ratio of the thickness of each layer in the sealing material sheet 1, the thickness ratio of the outermost layer 12: the intermediate layer 11: the outermost layer 12 may be in the range of 1: 2: 1 to 1: 30: 1. preferable. By setting the thickness ratio of each layer in this range, the heat resistance and the molding characteristics of the sealing material sheet 1 can be maintained in a favorable range.

<Production method of sealing material sheet>
[Sheet forming process]
Melt molding of each composition for the intermediate layer and the outermost layer, each of which has been described in detail above, is a molding method usually used in ordinary thermoplastic resins, that is, injection molding, extrusion molding, hollow molding, compression molding, It is performed by various molding methods such as rotational molding. As a method of forming the multilayer sheet, for example, a method of forming by co-extrusion using two or more kinds of melt-kneading extruders can be mentioned.

  The lower limit of the molding temperature during molding may be any temperature that exceeds the melting point of each sealing material composition. When a crosslinking agent is used, the upper limit of the molding temperature is a temperature at which crosslinking does not start during film formation according to the one-minute half-life temperature of the used crosslinking agent, that is, the gel fraction of the sealing material composition. Any temperature may be used as long as the temperature can be maintained at 0%. Here, in the method for producing a sealing material sheet of the present invention, a crosslinking agent is not essential in the sealing material composition, and even when a crosslinking agent is added, its content is less than 0.5% by mass. Is limited to For this reason, at the molding temperature of a normal low-density polyethylene resin, for example, under heating conditions of about 120 ° C., no change in the gel fraction appears, and cross-linking that substantially affects the physical properties of the resin does not proceed. In the case where the crosslinking treatment is performed by irradiation with ionizing radiation, it is possible to use a crosslinking agent having a higher half-life temperature for one minute than the conventional one, freed from the restriction of the heating conditions in the modularization step. In this case, even if the molding temperature is set higher than in the past, the gel fraction of the sealing material composition can be maintained at 0%. According to the production method in which the gel fraction of the encapsulant composition during film formation is maintained at 0%, it is possible to reduce the load applied to an extruder or the like during film formation and increase the productivity of the encapsulant sheet. It is.

[Cross-linking step]
A cross-linking step of performing a cross-linking treatment with ionizing radiation on the uncross-linked sealing material sheet after the above-mentioned sheet forming step is performed after the sheet forming step is completed, and the sealing material sheet is integrated with another member. It is preferably performed before the start of the solar cell module integration step. By this crosslinking treatment, a sealing material sheet having a gel fraction of 2% or more and 80% or less is obtained.

  Regarding the crosslinking treatment by irradiation with ionizing radiation, individual crosslinking conditions are not particularly limited. As a rough guide of the irradiation amount, it may be appropriately set so that the gel fraction of the intermediate layer after the crosslinking treatment is in a range of about 10% or more. Specifically, it can be performed by ionizing radiation such as electron beam (EB), α-ray, β-ray, γ-ray, neutron beam, etc. Among them, it is preferable to use an electron beam. Irradiation with ionizing radiation may be performed from either one side or both sides. From the viewpoint of improving productivity, single-sided irradiation, which is irradiation only from one outermost layer side, is preferable.

  When the irradiation of ionizing radiation is performed by the single-sided irradiation, the acceleration voltage is determined by the thickness of the sheet to be irradiated, and a larger sheet requires a larger acceleration voltage. For example, for a sheet having a thickness of 0.6 mm, irradiation is performed at 200 kV to 1000 kV, preferably 250 kV to 1000 kV. When the acceleration voltage is less than 200 kV, electrons do not transmit to the outermost layer on the non-irradiation surface side, and the heat resistance of the sealing material sheet 1 becomes insufficient. On the other hand, if the accelerating voltage exceeds 1000 kV, electrons uniformly pass through all layers of the multilayer sheet, and it becomes impossible to form a gradient structure of storage elastic modulus, which is a unique structure of the present invention. The irradiation dose ranges from 5 kGy to 800 kGy, preferably from 100 kGy to 500 kGy. Irradiation may be performed in an air atmosphere or a nitrogen atmosphere.

  Here, the gel fraction (%) means that 0.1 g of a sealing material sheet is put into a resin mesh, extracted with toluene at 60 ° C. for 4 hours, taken out with the resin mesh, dried, weighed, and weighed before and after extraction. The comparison was performed, and the mass% of the residual insoluble content was measured, and this was used as the gel fraction.

  In addition, this cross-linking treatment may be performed continuously in-line following the sheeting step, or may be performed off-line. When the crosslinking treatment is a general heat treatment, generally, the content of the crosslinking agent is 0.5 parts by mass or more and 1.5 parts by mass or less based on 100 parts by mass of all components of the sealing material sheet. However, in the encapsulant sheet of the present invention, the content of the crosslinking agent may be 0, and even if it is contained, it is preferably less than 0.5 part by mass. This can reduce the risk of a decrease in productivity due to gelling of the sealing material composition in the step of forming the sealing material composition into a sheet.

<Solar cell module>
Next, a preferred embodiment of the solar cell module of the present invention will be described with reference to FIG. FIG. 2 is a cross-sectional view illustrating an example of a layer configuration of a solar cell module 10 in which the sealing material sheet 1 of the present invention having a wavelength conversion function is arranged on the light receiving surface side of the solar cell element 3. The solar cell module 10 includes a transparent front substrate 4, a sealing material sheet 1 for the light receiving surface, a solar cell element 3, a sealing material sheet 2 for the non-light receiving surface, and a back surface protection from the light receiving surface side of the incident light. Sheets 5 are sequentially stacked.

  In the solar cell module 10, the sealing material sheet 1 arranged on the light receiving surface side is arranged on the light receiving surface side of the solar cell element, thereby exhibiting a wavelength conversion function and improving the power generation efficiency of the solar cell module 10. Let it. In addition, due to the excellent molding characteristics of the outermost layer, it is possible to firmly adhere to uneven surfaces such as electrodes of the solar cell element 3.

  In the solar cell module 10, the sealing material sheet 2 disposed on the non-light receiving surface side may be the same sheet as the sealing material sheet 1, but other polyethylene-based sealing materials having no wavelength conversion function. The sheet can be appropriately selected.

  As the sealing material sheet 2 disposed on the non-light receiving surface side, it is particularly preferable to use a polyethylene-based white sealing material sheet in which a white colorant is added to a polyethylene-based resin serving as a base resin and colored white. it can. As a colorant for forming the sealing material sheet 2 into a white sealing material sheet, a white colorant made of an inorganic compound can be preferably used. When the white encapsulant sheet containing such a white colorant is disposed as the encapsulant sheet 2 on the non-light-receiving surface side of the solar cell module 10, of the incident light into the solar cell module 10. By further guiding the sunlight that has reached the non-light-receiving surface side without entering the solar cell element 3 to the light-receiving surface side of the solar cell element 3 again, the power generation efficiency of the solar cell module 10 can be further improved. it can.

  The white colorant is not particularly limited, but for example, white pigments such as calcium carbonate, barium sulfate, zinc oxide, and titanium oxide can be preferably used. Among them, titanium oxide can be particularly preferably used from the viewpoint of versatility.

  The white pigment preferably has a particle size of 0.5 μm or more and 1.5 μm or less. When the particle size of the white pigment is within the above range, the white layer made of the pigment can efficiently reflect near infrared rays in addition to the visible light region, and thus can greatly contribute to improving the power generation efficiency of the solar cell module. A typical example of a white pigment having a diameter of 0.5 μm or more and 1.5 μm or less is titanium oxide, and it is preferable to use titanium oxide as the white pigment in order to enhance the reflection performance of sunlight.

  With respect to such improvement in power generation efficiency, it is desirable to whiten the sealing material layer on the non-light-receiving surface side of the solar cell module as described above. However, in addition to white, light reflectivity is obtained. With such a color tone, for example, it may be colored in yellow, green, light blue or the like.

  When the sealing material sheet 2 is a multilayer sheet similar to the sealing material sheet 1, it is more preferable that the coloring material is contained only in the intermediate layer. With such a configuration, it is possible to prevent the adhesion of the outermost layer from being reduced due to the influence of the coloring material.

  The layer configuration of the solar cell module of the present invention is not limited to the above embodiment. Since the encapsulant sheet 1 of the present invention has adhesiveness to both glass and metal, it can be used for solar cell modules of various configurations including a glass substrate and a metallic solar cell module by utilizing its properties. Can be used for general purposes. For example, in a solar cell module, even when one surface of a sealing material sheet faces a metal surface and the other surface faces a glass layer, the sealing material sheet of the present invention is preferably used. be able to.

  In the solar cell module 10, the above-mentioned module components including the sealing material sheets 1, 2 and the solar cell element 3 are sequentially laminated, integrated by vacuum suction or the like, and then formed by a laminating method or the like. Can be manufactured by thermocompression bonding as an integral molded body.

  In the solar cell module 10 of the present invention, conventionally known materials can be used for the transparent front substrate 4, the solar cell element 3, and the back surface protection sheet 5 which are members other than the sealing material sheet 1 without any particular limitation. . Further, the solar cell module 10 of the present invention may include members other than the above members.

  As described above, the present invention has been specifically described with reference to the embodiments. However, the present invention is not limited to the above embodiments, and can be implemented with appropriate modifications within the scope of the present invention.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples.

<Manufacture of encapsulant sheet for solar cell module>
The raw materials of the sealing material composition described below were mixed such that the content in the sealing material composition became the ratio of Table 1 below, respectively, and the sealing materials of Examples, Comparative Examples, and Reference Examples, respectively. A sealing material composition for forming a sealing material sheet for the inner layer and the outer layer of the sheet was used. Using an extruder having a diameter of 30 mm and a film forming machine having a T-die having a width of 200 mm, each encapsulant composition is produced at an extruding temperature of 210 ° C. and a take-up speed of 1.1 m / min to produce an encapsulant sheet for an inner layer and an outer layer. Then, the sealing material sheets for the inner layer and the outer layer were laminated to form one or three layers of sealing material sheets for solar cell modules (Examples, Comparative Examples, and Reference Examples). Each of these sealing material sheets had a thickness of 600 μm and a thickness ratio of the outer layer: the inner layer: the outer layer of 1: 5: 1. In addition, the following raw materials were used as raw materials of the sealing material composition.

[Polyethylene resin]
Metallocene linear low-density polyethylene (M-LLDPE): A metallocene linear low-density polyethylene having a density of 0.880 g / cm ³ and an MFR of 3.5 g / 10 min at 190 ° C. was used as a base resin (see Table 1). 1 described as “PE”).

[Silane-modified polyethylene resin]
Silane crosslinkable resin: A vinyltrimethoxy resin is used with respect to 98 parts by mass of a metallocene linear low-density polyethylene (M-LLDPE) having a density of 0.881 g / cm ³ and an MFR at 190 ° C. of 2 g / 10 minutes. A silane-crosslinkable resin comprising 2 parts by mass of silane and 0.1 parts by mass of dicumyl peroxide as a radical generator (reaction catalyst) was used as a silane-modified polyethylene resin mixed with a base resin. The density of this resin is 0.884 g / cm ³ , and the MFR at 190 ° C. is 1.8 g / 10 minutes (described as “S-PE” in Table 1).

[Light stabilizer A]
As a hindered amine light stabilizer, 2.28 parts by mass of a hindered amine light stabilizer (manufactured by BASF: Chimassorb 2020) is added to 100 parts by mass of powder obtained by pulverizing a Ziegler linear low-density polyethylene having a density of 0.880 g / cm ^3. Was melted and processed to prepare a pelletized master batch. (Indicated as "HALS1" in Table 1)

[Light stabilizer B]
1. As a hindered amine light stabilizer, a hindered amine light stabilizer (KEMIPROB62: KEMISTAB62) is used for 100 parts by mass of powder obtained by pulverizing Ziegler linear low-density polyethylene having a density of 0.880 g / cm ³ . 28 parts by mass were mixed, melted and processed to prepare a pelletized master batch. (Indicated as "HALS2" in Table 1)

[Wavelength conversion agent]
As a wavelength conversion agent, 1 part by mass of a triazole derivative (number average molecular weight: 3233) is mixed with 100 parts by mass of powder obtained by pulverizing Ziegler linear low-density polyethylene having a density of 0.880 g / cm ³ and melted and processed. Then, a pelletized master batch (MB) was prepared.

<Evaluation Example 1>
The sealing material sheets of Examples and Comparative Examples were subjected to a storage stability test (temperature: 40 ° C., humidity: 90% RH, for 3 months), and optical properties (HAZE) before and after the storage stability test (JIS K7136, Murakami Color Research Co., Ltd.) In some cases, the haze / transmittance system HM150 was used) and the glass adhesion was evaluated. Regarding the optical characteristics, “○” indicates a haze of 5.0% or less, and “×” indicates a haze of more than 5.0%. Glass adhesion was measured using a peel tester (trade name “TENSILON RTA-1150-H” manufactured by A & D Corporation) at 180 ° peel at 23 ° C. under peel conditions of 50 mm / min. 30N / 15 mm was evaluated as “◎”, 20 N / 15 mm or more was evaluated as “／”, and less than 20 N / 15 mm was evaluated as “x”. Table 2 shows the results.

<Evaluation Example 2>
On the glass substrate (white plate float semi-tempered glass JPT3.2 75 mm x 50 mm x 3.2 mm), the sealing material sheets of Examples and Comparative Examples cut to a width of 15 mm were laminated, and vacuum heating was performed at 150 ° C for 18 minutes. Processing was performed with a laminator, and a solar cell module evaluation sample was obtained for each.

For the encapsulant sheets of Examples and Comparative Examples, using a Super Xenon weather meter manufactured by Suga Test Instruments Co., Ltd., under conditions of irradiance 180 W / m ² , black panel temperature (BPT) 63 ° C., and humidity 50%, for 165 hours An irradiation test was performed. The quantum yield of the sealing sheet before and after the test was measured. Compared to the initial stage, those with a quantum yield retention rate of more than 50% were marked with “○”, those with 20% or more and 50% or less were marked with “△”, and those with 20% or less were marked with “x”. Table 2 shows the results.

  From Table 2, it can be seen that the examples of the present invention were able to maintain the optical characteristics, glass adhesion, and wavelength conversion function in the preferred ranges even after the storage stability test. As described above, the wavelength conversion type sealing material sheet of the present invention is a sealing material sheet having optical properties, glass adhesion, wavelength conversion function, and excellent weather resistance and durability relating to their physical properties and functions. You can see that.

DESCRIPTION OF SYMBOLS 1 Encapsulant sheet 11 Intermediate layer 12 Outermost layer 2 Encapsulant sheet for non-light-receiving side 3 Solar cell element 4 Transparent front substrate 5 Back protective sheet 10 Solar cell module

Claims (6)

From the light receiving surface side of the incident light, a transparent front substrate made of glass , a sealing material sheet for the light receiving surface side, a solar cell element, a sealing material sheet for the non-light receiving surface side, and a back surface protection sheet are sequentially laminated. A solar cell module,
The light-receiving surface-side sealing material sheet is a multilayer sheet including an intermediate layer and outermost layers disposed on both surfaces thereof,
Said intermediate layer and said outermost layer, and a density of 0.870 g / cm ³ or more 0.970 g / cm ³ or less of low density polyethylene-based resin,
The intermediate layer contains an organic wavelength conversion agent,
When the outermost layer contains the organic wavelength converter, the content ratio is smaller than the content ratio of the organic wavelength converter in the intermediate layer,
The intermediate layer and the outermost layer contain only one kind of hindered amine light stabilizer,
The hindered amine light stabilizer, a sealing material sheet is below the light stabilizer (A),
The sealing material sheet for the non-light receiving surface side is a polyethylene-based white sealing material sheet,
Solar cell module.
Light stabilizer (A): a hindered amine light stabilizer having three or more piperidine rings in the side chain of the monomer unit and having a molecular weight of 1,000 to 10,000.   The content of the light stabilizer (A) in the intermediate layer and the outermost layer of the light-receiving surface side sealing material sheet is 0.1% by mass or more and 0.5% by mass or less. Solar module.   The solar cell module according to claim 1, wherein the organic wavelength converter is a wavelength converter having a number average molecular weight of 100 or more and 1000 or less.   The solar cell module according to any one of claims 1 to 3, wherein the organic wavelength conversion agent is a derivative of any one of pyrazine, pyridine, and triazole or a mixture thereof.   The content ratio of the organic wavelength conversion agent in the outermost layer is １ ／ or less of the content ratio of the organic wavelength conversion agent in the intermediate layer, according to any one of claims 1 to 4. Solar cell module.   The solar cell module according to claim 1, wherein the outermost layer further contains a silane-modified polyethylene-based resin.

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