JP5593215B2 - Multilayer body for solar cell and solar cell module manufactured using the same - Google Patents

Description

  The present invention relates to a solar cell multilayer body and a solar cell module produced using the same, and more specifically, the formation of the solar cell module is easy, the crosslinking step can be omitted, and transparency, moisture resistance, The present invention relates to a solar cell multilayer body suitably used as a solar cell sealing material excellent in sealing property and handling property (rigidity), and a solar cell module produced using the same.

In recent years, with increasing awareness of environmental issues such as global warming, expectations are increasing especially for photovoltaic power generation in terms of its cleanliness and non-polluting properties. The solar cell constitutes the central part of a photovoltaic power generation system that directly converts sunlight energy into electricity. In general, a plurality of solar cell elements (cells) are wired in series and in parallel as the structure, and various packaging is performed to protect the cells, thereby forming a unit. The unit incorporated in this package is called a solar cell module. Generally, the surface exposed to sunlight is covered with a transparent base material (front sheet) such as glass as an upper protective material, and a thermoplastic (for example, ethylene-vinyl acetate) The gap is filled with a resin layer (encapsulant) made of a copolymer, and the back surface is protected by a back surface sealing sheet (back sheet) with the lower protective material.
Since these solar cell modules are mainly used outdoors, various characteristics are required for the structure and material structure thereof. The above-mentioned encapsulant has flexibility and impact resistance for protecting the solar cell element, heat resistance when the solar cell module generates heat, and transparency for efficiently reaching the solar cell element ( Total light transmittance, etc.), durability, dimensional stability, flame retardancy, moisture resistance, etc. are mainly required.

Currently, an ethylene-vinyl acetate copolymer (hereinafter sometimes abbreviated as EVA) is widely used as a material for sealing a solar cell element in a solar cell module from the viewpoint of flexibility, transparency and the like. (For example, refer to Patent Document 1). In addition, for the main purpose of imparting heat resistance to EVA, crosslinking using an organic peroxide as a crosslinking agent is performed. Therefore, the process of producing the EVA sheet | seat which added the crosslinking agent (organic peroxide) and the crosslinking adjuvant in advance, and sealing a solar cell element using the obtained sheet | seat is employ | adopted.
However, when a solar cell module is manufactured using an EVA sheet, acetic acid gas is generated due to thermal decomposition of EVA due to various conditions such as thermocompression bonding, which adversely affects the work environment and manufacturing apparatus, and circuit corrosion of the solar cell. In addition, there is a problem such as peeling that occurs at the interface of each member such as a solar cell element, front sheet, and back sheet.
Further, EVA has insufficient moisture resistance, specifically water vapor barrier properties (for example, a water vapor transmission rate of 25 to 35 g / (m ² · 24 at a thickness of 0.3 mm, a temperature of 40 ° C., and a relative humidity of 90%). When used in an environment such as high humidity, there is a concern that moisture reaches the solar cell element, causing deterioration of the solar cell and a decrease in power generation efficiency.

  In order to solve the above problems, for example, Patent Document 2 discloses a solar cell encapsulant using an ethylene-α-olefin copolymer. Patent Document 3 discloses a solar cell sealing material using a silane-modified ethylene resin. Further, as examples of resins having better moisture resistance than EVA, high-density polyethylene and cyclic olefin resins in which a cyclic olefin is introduced into a molecular chain are known. For example, Patent Document 4 discloses a cyclic olefin resin. A solar cell encapsulating material using a norbornene-based ring-opening polymer hydride is disclosed. Further, Patent Document 5 discloses a solar cell sealing material in which an adhesive / heat-resistant layer and a buffer layer are laminated.

JP 58-60579 A JP 2000-91611 A Japanese Patent Laying-Open No. 2005-19975 JP 2009-79101 A International Publication No. 2006/095762 Pamphlet

  However, although the solar cell sealing material using the ethylene-α-olefin copolymer disclosed in Patent Document 2 can avoid the influence of acetic acid gas due to the thermal decomposition of EVA, it is suitable as a solar cell sealing material. There is no specific disclosure about the usage form of the ethylene-α-olefin copolymer. This is considered to be because the technique disclosed in Patent Document 2 attempts to achieve various characteristics such as heat resistance and transparency on the premise of crosslinking treatment as in the case of conventional EVA.

  Next, although the solar cell sealing material using the silane-modified ethylene-based resin disclosed in Patent Document 3 is excellent in adhesiveness to various base materials in the solar cell module, It has been difficult to obtain a sealing material that has excellent properties, moisture resistance and transparency at the same time. That is, when the crystallinity of the encapsulant is lowered and flexibility is imparted, the sealing property and transparency are improved, while the moisture-proof property is lowered as the crystallinity is lowered.

  High density polyethylene has relatively high moisture resistance, is inexpensive, and is widely used industrially. However, since it has too high rigidity and insufficient flexibility, a solar cell element is used as a solar cell member. It was inferior in stopping property and protective property (cushioning property), and also had insufficient transparency and low power generation efficiency.

  A solar cell encapsulant using a hydride of norbornene-based ring-opening polymer as a cyclic olefin resin disclosed in Patent Document 4 is excellent in moisture resistance and transparency, but the cyclic olefin resin used is a relatively expensive raw material Therefore, it was inferior in economic efficiency. In addition, since cyclic olefin-based resins usually have a high viscosity at the time of melting, there is a concern that the sealing performance at the time of sealing the solar cell element is inferior. There is no description or suggestion regarding the sealing property when stopping. For example, when the sealing process is performed under high temperature and high pressure in order to increase the fluidity (fillability) of the resin used, the solar cell element or wiring may be altered due to high temperature, or the solar cell element may be damaged due to overpressure. Problems can arise.

  Next, the solar cell sealing material formed by laminating the adhesive / heat-resistant layer and the buffer layer disclosed in Patent Document 5 is excellent in transparency, flexibility, heat resistance, and adhesiveness by adopting a laminated structure. Although it is easy to obtain a solar cell sealing material, the laminated structure is (solar cell element) / hard layer / soft layer, and the layer that adheres to and protects the solar cell element is hard, so that sealing properties and protective properties (cushion) ) And the like. That is, it has been difficult to obtain a multilayer body for solar cells and a solar cell encapsulant that are excellent in transparency, moisture resistance, sealing properties and handling properties (rigidity), which are the objectives of the present invention.

  Therefore, in view of the problems of the prior art, the object of the present invention is that the formation of a solar cell module is easy, the crosslinking step can be omitted, and transparency, moisture resistance, sealing properties, handling properties (rigidity), etc. It is providing the multilayer body for solar cells used suitably as an outstanding solar cell sealing material, and a solar cell module produced using the same.

  The present invention has a resin melting point (I) containing a silane-modified ethylene resin (A) as at least one outermost layer, and a crystal melting peak measured at a heating rate of 10 ° C./min in differential scanning calorimetry. A solar cell having a resin layer (II) containing an ethylene resin (B) having a temperature of 100 to 145 ° C. and a crystal melting heat of 120 to 190 J / g and a crystal nucleating agent (C) It relates to a multilayer body.

  Moreover, this invention relates to the solar cell module produced using the said multilayer body for solar cells, an upper protection material, a photovoltaic cell, and a lower protection material.

According to the present invention, a solar cell module can be easily formed, a crosslinking step can be omitted, and it is suitably used as a solar cell encapsulant excellent in transparency, moisture resistance, sealing properties, handling properties (rigidity), and the like. The multilayer body for solar cells used and the solar cell module produced using the same can be provided.
Moreover, since a bridge | crosslinking process can be abbreviate | omitted, the productivity in a solar cell module manufacturing process can be improved. Further, the manufacturing equipment can be applied to a roll-to-roll manufacturing equipment in addition to a batch manufacturing equipment, and as a result, it can be expected that the manufacturing cost of the solar cell module will be greatly reduced.

It is a schematic sectional drawing which shows an example of the solar cell module of this invention.

  In the present specification, the “main component” is a gist that allows other components to be contained within a range that does not interfere with the action and effect of the resin constituting each resin layer of the multilayer body for solar cell of the present invention. . Further, this term does not limit the specific content, but generally, when the total component of the resin composition is 100 parts by mass, it is 50 parts by mass or more, preferably 65 parts by mass or more, Preferably, the component occupies a range of 80 parts by mass or more and 100 parts by mass or less.

[Resin layer (I)]
The resin layer (I) is a resin layer containing a silane-modified ethylene resin (A). Here, the resin layer (I) is a resin layer mainly composed of a silane-modified ethylene resin (A) or a resin mainly composed of a mixture of a silane-modified ethylene resin (A) and a polyethylene resin (F). Includes layers. In addition, the resin layer (I) mainly has a function of expressing functions as a surface layer, a sealing layer, and an adhesive layer in the solar cell multilayer body of the present invention. For this reason, at least one of the outermost layers of the multilayer body for solar cell of the present invention needs to be the resin layer (I).

<Silane-modified ethylene resin (A)>
The silane-modified ethylene resin (A) used in the present invention is usually obtained by melt-mixing a polyethylene resin, a vinylsilane compound, and a radical generator at a high temperature (about 160 ° C. to 220 ° C.) and graft polymerization. it can.

(Polyethylene resin)
Although it does not specifically limit as said polyethylene-type resin, Specifically, a low density polyethylene, a medium density polyethylene, a high density polyethylene, an ultra-low density polyethylene, or a linear low density polyethylene is mentioned. These may be used alone or in combination of two or more.

In the present invention, a polyethylene resin having a low density is preferably used because of its excellent transparency and flexibility. Specifically, the polyethylene resin is preferably a density of 0.850~0.920g / cm ^3, in particular, the density is preferably a linear low density polyethylene 0.860~0.880g / cm ^3. Further, a polyethylene resin having a low density and a polyethylene resin having a high density may be used in combination. Use in combination is preferred because the balance of transparency, flexibility and heat resistance can be adjusted relatively easily.

  Examples of the low-density polyethylene resin suitably used in the present invention include a random copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms. Examples of the α-olefin copolymerized with ethylene include propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, and 3-methyl-butene. -1,4-methyl-pentene-1 and the like. In the present invention, propylene, 1-butene, 1-hexene, and 1-octene are preferably used as the α-olefin copolymerized with ethylene from the viewpoints of industrial availability, various characteristics, and economical efficiency. It is done. The α-olefin copolymerized with ethylene may be used alone or in combination of two or more.

  Moreover, as content of the alpha olefin copolymerized with ethylene, it is 2 mol% or more normally with respect to all the monomer units in an ethylene-alpha-olefin random copolymer, Preferably it is 40 mol% or less, More preferably, it is 3-30 mol%, More preferably, it is 5-25 mol%. Within this range, the crystallinity is reduced by the copolymerization component, so that the transparency is improved and problems such as blocking of the raw material pellets are less likely to occur. In addition, the kind and content of the α-olefin copolymerized with ethylene can be qualitatively and quantitatively analyzed by a well-known method, for example, a nuclear magnetic resonance (NMR) measuring apparatus or other instrumental analyzer.

  The ethylene-α-olefin random copolymer may contain monomer units based on monomers other than α-olefin. Examples of the monomer include cyclic olefins, vinyl aromatic compounds (such as styrene), polyene compounds, and the like. The content of the monomer unit is 20 mol% or less and more preferably 15 mol% or less when the total monomer units in the ethylene-α-olefin random copolymer is 100 mol%. preferable. Further, the steric structure, branching, branching degree distribution and molecular weight distribution of the ethylene-α-olefin random copolymer are not particularly limited. For example, a copolymer having a long chain branch generally has mechanical properties. It is favorable, and there is an advantage that the melt tension (melt tension) at the time of molding the sheet is increased and the calendar moldability is improved. A copolymer having a narrow molecular weight distribution polymerized using a single site catalyst has advantages such as a low molecular weight component and a relatively low blocking of raw material pellets.

  The melt flow rate (MFR) of the ethylene-α-olefin random copolymer is not particularly limited, but usually MFR (JIS K7210, temperature: 190 ° C., load: 21.18 N) is 0.1. What is about 1-100 g / 10min and what is 0.3-10 g / 10min from a moldability and various characteristics are used suitably.

  The method for producing the ethylene-α-olefin random copolymer is not particularly limited, and a known polymerization method using a known olefin polymerization catalyst can be employed. For example, slurry polymerization method, solution polymerization method, bulk polymerization method, gas phase polymerization method using multi-site catalyst represented by Ziegler-Natta type catalyst, single site catalyst represented by metallocene catalyst and post metallocene catalyst And a bulk polymerization method using a radical initiator. In the present invention, since the low-density ethylene-α-olefin random copolymer used is a relatively soft resin, it is easy to granulate after polymerization, prevent blocking of raw material pellets, etc. From this viewpoint, a polymerization method using a single-site catalyst that can polymerize a raw material having a low molecular weight component and a narrow molecular weight distribution is suitably used.

(Vinylsilane compound)
The vinyl silane compound is not particularly limited as long as it is graft-polymerized with the above polyethylene resin. For example, vinyl trimethoxy silane, vinyl triethoxy silane, vinyl tripropoxy silane, vinyl triisopropoxy silane, vinyl tri Butoxysilane, vinyltripentyloxysilane, vinyltriphenoxysilane, vinyltribenzyloxysilane, vinyltrimethylenedioxysilane, vinyltriethylenedioxysilane, vinylpropionyloxysilane, vinyltriacetoxysilane, and vinyltricarboxysilane At least one selected from the group consisting of can be used. In the present invention, vinyltrimethoxysilane is preferably used from the viewpoints of reactivity, adhesiveness and color tone.

  Moreover, although the addition amount of this vinylsilane compound is not specifically limited, It is about 0.01-10.0 mass parts normally with respect to 100 mass parts of polyethylene-type resin to be used, and 0.3-8. It is more preferable to add 0 part by mass, and it is more preferable to add 1.0 to 5.0 parts by mass.

(Radical generator)
The radical generator is not particularly limited, and examples thereof include hydroperoxides such as diisopropylbenzene hydroperoxide and 2,5-dimethyl-2,5-di (hydroperoxy) hexane; -Butyl peroxide, t-butyl cumyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, 2,5-dimethyl-2,5-di (t -Peroxy) dialkyl peroxides such as hexyne-3; bis-3,5,5-trimethylhexanoyl peroxide, octanoyl peroxide, benzoyl peroxide, o-methylbenzoyl peroxide, 2,4-dichlorobenzoylper Diacyl peroxides such as oxide; t-butylperoxya Tate, t-butylperoxy-2-ethylhexanoate, t-butylperoxypivalate, t-butylperoxyoctoate, t-butylperoxyisopropylcarbonate, t-butylperoxybenzoate, di-t- Peroxyesters such as butyl peroxyphthalate, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, 2,5-dimethyl-2,5-di (benzoylperoxy) hexyne-3; methyl ethyl ketone Examples thereof include organic peroxides such as ketone peroxides such as peroxide and cyclohexanone peroxide, or azo compounds such as azobisisobutyronitrile and azobis (2,4-dimethylvaleronitrile).

  Moreover, the addition amount of the radical generator is not particularly limited, but is usually about 0.01 to 5.0 parts by mass with respect to 100 parts by mass of the polyethylene resin used, and 0.02 to 1 It is more preferable to add 0.0 part by mass, and it is more preferable to add 0.03 to 0.5 part by mass. Furthermore, the residual amount of the radical generator is preferably 0.001% by mass or less in each resin layer constituting the multilayer body for solar cell of the present invention, and the gel fraction is preferably 30% or less.

  The silane-modified ethylene resin (A) and each resin layer used in the present invention preferably contain substantially no silanol condensation catalyst that promotes the condensation reaction between silanols. Specific examples of the silanol condensation catalyst include dibutyltin diacetate, dibutyltin dilaurate, dibutyltin dioctate, and dioctyltin dilaurate. Here, being substantially not contained means 0.05 parts by mass or less, preferably 0.03 parts by mass or less with respect to 100 parts by mass of the resin.

  Here, the reason why it is preferable that a silanol condensation catalyst is not substantially contained is that, in the present invention, polar groups such as silanol groups grafted on the polyethylene resin to be used without actively proceeding with the silanol crosslinking reaction. Such as hydrogen bond and covalent bond between glass and adherend (glass, various plastic sheets (appropriate surface treatment such as corona treatment is used with a wetting index of 50 mN / m or more is suitable), metal, etc.) This is because the purpose is to develop adhesiveness by action.

(Silane-modified ethylene resin (A))
As described above, the silane-modified ethylene resin (A) used in the present invention is usually obtained by melt-mixing the above-mentioned polyethylene resin with a vinylsilane compound and a radical generator at a high temperature (about 160 ° C. to 220 ° C.) and graft polymerization. It is obtained. Therefore, the density of the silane-modified ethylene resin (A) used in the present invention and the preferable range of MFR are the same as the density of the polyethylene resin and the preferable range of MFR.

  As a specific example of the silane-modified ethylene resin (A) used in the present invention, trade name “LINKLON” manufactured by Mitsubishi Chemical Corporation can be exemplified.

[Resin layer (I)]
The resin layer (I) is a resin layer mainly composed of a silane-modified ethylene resin (A) or a resin layer mainly composed of a mixture of a silane-modified ethylene resin (A) and a polyethylene resin (F). It doesn't matter. As described above, the silane-modified ethylene-based resin (A) can be usually obtained by melt-mixing a polyethylene-based resin, a vinyl silane compound, and a radical generator at a high temperature, and performing graft polymerization. When the polyethylene resin used for using the radical generator is partially crosslinked, gel or fish eye may be mixed in, or the vinylsilane compound or radical generator used may remain unreacted. Therefore, in this invention, it is more preferable that it is a resin layer which has as a main component the mixture of silane modified ethylene resin (A) and polyethylene resin (F). It is preferable to use the mixture because it improves economic efficiency and relatively easily adjusts various properties such as flexibility, transparency and heat resistance.

  Here, the polyethylene resin (F) is not particularly limited, but is mixed with the silane-modified ethylene resin (A) to contain the silane-modified ethylene resin (A) in the resin layer (I). While adjusting the amount, various properties such as flexibility, transparency, sealing properties and heat resistance of the resin layer (I) are adjusted. Specifically, the same resin as the polyethylene resin used when obtaining the silane-modified ethylene resin (A), that is, low density polyethylene, medium density polyethylene, high density polyethylene, ultra low density polyethylene, or linear Low density polyethylene is mentioned. These may be used alone or in combination of two or more.

  The melt flow rate (MFR) of the polyethylene resin (F) used in the present invention is not particularly limited, but usually MFR (JIS K7210, temperature: 190 ° C., load: 21.18 N) is 0.1. What is about 5-100 g / 10min, More preferably, it is 2-50 g / 10min, More preferably, it is 3-30 g / 10min. Here, the MFR may be selected in consideration of molding processability when molding a sheet, adhesion when sealing a solar cell element (cell), a wraparound condition, and the like. For example, when calendering a sheet, the MFR is preferably relatively low, specifically about 0.5 to 5 g / 10 min from the handling property when the sheet is peeled off from the forming roll, In the case of extrusion molding using a, MFR is preferably 2 to 50 g / 10 min, more preferably 3 to 30 g / 10 min from the viewpoint of reducing the extrusion load and increasing the extrusion rate. Furthermore, MFR is preferably 2 to 50 g / 10 min, more preferably 3 to 30 g / 10 min from the viewpoint of adhesion and ease of wraparound when sealing a solar cell element (cell). Good.

In the present invention, the polyethylene resin (F) may be the same resin as the polyethylene resin used in obtaining the silane-modified ethylene resin (A) or a different resin. It is preferable that they are the same resin from the viewpoints of compatibility and transparency when mixed. Moreover, in this invention, since transparency and a softness | flexibility become favorable, a polyethylene-type resin with a low density is used suitably. Specifically, the polyethylene resin is preferably a density of 0.850~0.920g / cm ^3, the density is more preferably linear low density polyethylene 0.860~0.880g / cm ^3. Furthermore, in the linear low density polyethylene, it is particularly preferable that the α-olefin as a copolymerization component is the same as the polyethylene resin used when obtaining the silane-modified ethylene resin (A).

  In the present invention, specific examples of polyethylene resins having a low density that are preferably used include trade names “Engage”, “Affinity”, and “Infuse” manufactured by Dow Chemical Co., Ltd. ", Trade name" TAFMER A "," TAFMER P "manufactured by Mitsui Chemicals, Inc., trade name" Kernel "manufactured by Nippon Polyethylene Co., Ltd., etc. it can.

  The mixing mass ratio when the resin layer (I) is a resin layer mainly composed of a mixture of the silane-modified ethylene resin (A) and the polyethylene resin (F) is not particularly limited. The modified ethylene resin (A) / polyethylene resin (F) ratio is 1 to 99/99 to 1, preferably 2 to 70/98 to 30, more preferably 3 to 40/97 to 60. is there. Within this range, the content of the silane-modified ethylene resin (A) in the resin layer (I), that is, the silane-modified group concentration can be easily adjusted, and the adhesive layer is the main role of the resin layer (I). While maintaining the functions of the surface layer, it is preferable because various properties such as flexibility, transparency, sealing properties and heat resistance as the surface layer and the sealing layer can be adjusted relatively easily.

The resin layer (I) has a role of expressing functions mainly as a surface layer, a sealing layer, and an adhesive layer in the solar cell multilayer body of the present invention. For this reason, it is preferable that resin used for resin layer (I) has a softness | flexibility. On the other hand, the resin layer (I) is also required to prevent blocking due to softening as a surface layer. In the present invention, although not particularly limited, the Vicat softening temperature of the resin layer (I) is preferably 60 ° C. or less, more preferably 30 ° C. or more and less than 60 ° C., and 35 ° C. or more. More preferably, it is 55 degrees C or less. Within this range, the flexibility of the resin layer (I) is sufficiently secured, and it is difficult to block in a normal storage environment (temperature 30 ° C., humidity 50%), which is preferable. The Vicat softening temperature can be measured according to JIS K7206. Specifically, the heat transfer medium is raised at a rate of 50 ° C./hour while applying a total load of 10 N (A method) through a needle-like indenter with a tip cross-sectional area of 1 mm ² placed perpendicular to the test piece in the heating bath. This is the temperature when the tip of the indenter penetrates 1 mm into the test piece.

  The mixing method in the case of using a mixture of the silane-modified ethylene resin (A) and the polyethylene resin (F) for the resin layer (I) is not particularly limited. Or may be supplied after all materials are melted and mixed to produce pellets. In the present invention, as described above, since the vinylsilane compound and the radical generator added when obtaining the silane-modified ethylene resin (A) may remain without reacting, the silane-modified ethylene resin When mixing (A) and a polyethylene-type resin (F), it is preferable to remove a volatile matter with a vacuum vent.

  The thickness of the resin layer (I) is not particularly limited, but is preferably 0.02 to 0.7 mm from the viewpoint of sealing performance and economic efficiency of the solar cell element (cell). It is more preferable that it is 0.05-0.6 mm.

[Resin layer (II)]
The resin layer (II) is provided on at least one side of the resin layer (I), and has a crystal melting peak temperature of 100 to 145 ° C. and a crystal melting heat amount measured at a heating rate of 10 ° C./min in differential scanning calorimetry. It is a resin layer containing an ethylene-based resin (B) of 120 to 190 J / g and a crystal nucleating agent (C). Further, the resin layer (II) is an excellent moisture-proof property (water vapor barrier property) for suppressing deterioration due to moisture mainly in the solar cell element (cell) or wiring in the multilayer body for solar cell of the present invention, It has the role of imparting handling properties (rigidity) at the time of battery module production, rigidity (waistness) to the flexible solar cell module, and excellent transparency for expressing sufficient power generation efficiency in the solar cell.

<Ethylene resin (B)>
The ethylene-based resin (B) used in the solar cell multilayer body of the present invention is not particularly limited as long as the thermal characteristics are satisfied, but an ethylene homopolymer or ethylene and an α- Copolymers with olefins or mixtures thereof are preferably used. Examples of the α-olefin copolymerized with ethylene include propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, and 3-methyl-butene. -1,4-methyl-pentene-1 and the like. In the present invention, propylene, 1-butene, 1-hexene, and 1-octene are preferably used as the α-olefin copolymerized with ethylene from the viewpoints of industrial availability, various characteristics, and economical efficiency. It is done. The α-olefin copolymerized with ethylene may be used alone or in combination of two or more. In the present invention, an ethylene homopolymer that satisfies the thermal characteristics, or ethylene and at least one selected from 1-butene, 1-hexene, and 1-octene, preferably two or more α-olefins In combination with the crystal nucleating agent (C), the moisture-proof (water vapor barrier property) for suppressing deterioration of the solar cell element (cell), wiring, etc. due to moisture, at the time of manufacturing the solar cell module Various characteristics as resin layer (II) such as handling property (rigidity), rigidity (flexibility) for flexible solar cell module, and excellent transparency to develop sufficient power generation efficiency for solar cell are efficiently given. This is preferable because it is possible.

  When the copolymer of ethylene and α-olefin is used, the content of α-olefin is 0.1 to 3.0 with respect to all monomer units in the ethylene-α-olefin copolymer. It is preferable that it is mass%, It is more preferable that it is 0.3 mass% or more or 2.8 mass% or less, It is further more preferable that it is 0.5 mass% or more or 2.6 mass% or less. If the α-olefin is within this range, it is preferable because a multilayer body for solar cells excellent in balance between moisture resistance, transparency, heat resistance and rigidity can be provided.

  Further, the catalyst used for the polymerization of the ethylene resin (B) is not particularly limited. For example, Philips is a Ziegler-Natta type catalyst composed of titanium chloride and an organoaluminum compound or a chromium compound such as chromium oxide. Examples thereof include multi-site catalysts typified by type catalysts and single-site catalysts typified by metallocene-based catalysts and post-metallocene-based catalysts. In the present invention, it is preferable to use a single site catalyst for the reason described later.

  Here, an ethylene homopolymer or ethylene-α-olefin copolymer polymerized using a single site catalyst has a small molecular weight distribution index (Mw / Mn) and a relatively uniform molecular length. When the crystal nucleating agent (C) is added, it becomes possible to form fine crystals, so that transparency and moisture resistance can be improved efficiently. For these reasons, the molecular weight distribution index (Mw / Mn) of the ethylene resin (B) is preferably 2.5 to 5.0, more preferably 2.6 or more or 4.8 or less. More preferably, it is 2.8 or more or 4.5 or less. The molecular weight distribution index (Mw / Mn) can be determined from the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) using a known method, for example, a high temperature GPC system.

  An example of the single site catalyst is a metallocene catalyst in which a metallocene compound and methylaluminoxane are combined. The characteristics of ethylene homopolymers and ethylene-α-olefin copolymers that are polymerized using a single-site catalyst are that, in addition to the narrow molecular weight distribution described above, if compared at the same density, a multi-site catalyst is used. In addition, the heat of crystal melting is lower than that of the polymerized resin.

  The ethylene-based resin (B) used in the present invention has a specific thermal characteristic, that is, a crystal melting peak temperature measured at a heating rate of 10 ° C./minute in differential scanning calorimetry, and a crystal melting heat amount of 120 to 190 J. / G. More preferably, the crystal melting peak temperature is 105 ° C. or higher, more preferably 110 ° C. or higher, and the upper limit is 145 ° C. More preferably, the heat of crystal fusion is 130 to 185 J / g, still more preferably 140 to 183 J / g. Here, if the crystal melting peak temperature and the crystal melting heat amount are within the above ranges, the combination with the crystal nucleating agent (C) has excellent moisture resistance, transparency, heat resistance, and the like. This is preferable because rigidity can be imparted. The crystal melting peak temperature and the crystal melting heat quantity can be measured in accordance with JIS K7121 and JIS K7122, respectively, using a differential scanning calorimeter.

The density of the ethylene-based resin (B) is preferably 0.910~0.948g / cm ^3, more preferably 0.915 g / cm ³ or more, or 0.947 g / cm ³ or less 0.920 g / cm ³ or more or 0.942 g / cm ³ or less is more preferable. Here, it is preferable that the density is within the above range, since excellent moisture resistance, transparency, heat resistance and rigidity can be imparted to the multilayer body for solar cell of the present invention in a well-balanced manner.

  Further, the melt flow rate (MFR) of the ethylene-based resin (B) is not particularly limited, but usually MFR (JIS K7210, temperature: 190 ° C., load: 21.18 N) is 0.1. Those having a thickness of about ˜100 g / 10 min and those having a moldability of 0.3 to 10 g / 10 min are preferably used in view of moldability and various characteristics.

  Specific examples of the ethylene-based resin (B) include those polymerized with a single site catalyst, trade name “CREOLEX” of Asahi Kasei Chemicals Corporation, trade name “Lumicene” of TOTAL PETROCHEMICALS, Ube The product name “UMERIT” manufactured by Maruzen Polyethylene Co., Ltd. and the product name “Suntec HD” manufactured by Asahi Kasei Chemicals Co., Ltd. Product name “Novatec HD” and the like.

<Crystal nucleating agent (C)>
As long as the crystal nucleating agent (C) used in the present invention has an effect of improving transparency by mainly reducing the spherulite size of the ethylene-based resin (B), increasing the heat of crystal fusion, and improving rigidity, The kind is not particularly limited. For example, dibenzylidene sorbitol (DBS) compounds, 1,3-O-bis (3,4 dimethylbenzylidene) sorbitol, dialkyl benzylidene sorbitol, diacetals of sorbitol having at least one chlorine or bromine substituent, di (methyl or ethyl substitution) Benzylidene) sorbitol, bis (3,4-dialkylbenzylidene) sorbitol having a carbocyclic substituent, aliphatic, alicyclic, and aromatic carboxylic acids, dicarboxylic acids or polybasic polycarboxylic acids, corresponding Metal salt compounds of organic acids such as anhydrides and metal salts, bicyclic dicarboxylic acids and salt compounds such as cyclic bis-phenol phosphate, disodium bicyclo [2.2.1] heptene dicarboxylic acid, bicyclo [2. 2.1] Heptane-dicarboxyle Bicyclic dicarboxylate saturated metal or organic salt compounds such as 1,3: 2,4-O-dibenzylidene-D-sorbitol, 1,3: 2,4-bis-O- (m -Methylbenzylidene) -D-sorbitol, 1,3: 2,4-bis-O- (m-ethylbenzylidene) -D-sorbitol, 1,3: 2,4-bis-O- (m-isopropylbenzylidene) -D-sorbitol, 1,3: 2,4-bis-O- (mn-propylbenzylidene) -D-sorbitol, 1,3: 2,4-bis-O- (mn-butylbenzylidene) -D-sorbitol, 1,3: 2,4-bis-O- (p-methylbenzylidene) -D-sorbitol, 1,3: 2,4-bis-O- (p-ethylbenzylidene) -D-sorbitol 1,3: 2,4-bis-O (P-Isopropylbenzylidene) -D-sorbitol, 1,3: 2,4-bis-O- (pn-propylbenzylidene) -D-sorbitol, 1,3: 2,4-bis-O- (p -N-butylbenzylidene) -D-sorbitol, 1,3: 2,4-bis-O- (2,3-dimethylbenzylidene) -D-sorbitol, 1,3: 2,4-bis-O- (2 , 4-Dimethylbenzylidene) -D-sorbitol, 1,3: 2,4-bis-O- (2,5-dimethylbenzylidene) -D-sorbitol, 1,3: 2,4-bis-O- (3 , 4-Dimethylbenzylidene) -D-sorbitol, 1,3: 2,4-bis-O- (3,5-dimethylbenzylidene) -D-sorbitol, 1,3: 2,4-bis-O- (2 , 3-Diethylbenzylidene) -D-sorby Tol, 1,3: 2,4-bis-O- (2,4-diethylbenzylidene) -D-sorbitol, 1,3: 2,4-bis-O- (2,5-diethylbenzylidene) -D- Sorbitol, 1,3: 2,4-bis-O- (3,4-diethylbenzylidene) -D-sorbitol, 1,3: 2,4-bis-O- (3,5-diethylbenzylidene) -D- Sorbitol, 1,3: 2,4-bis-O- (2,4,5-trimethylbenzylidene) -D-sorbitol, 1,3: 2,4-bis-O- (3,4,5-trimethylbenzylidene ) -D-sorbitol, 1,3: 2,4-bis-O- (2,4,5-triethylbenzylidene) -D-sorbitol, 1,3: 2,4-bis-O- (3,4, 5-triethylbenzylidene) -D-sorbitol, 1,3: 2 4-bis-O- (p-methyloxycarbonylbenzylidene) -D-sorbitol, 1,3: 2,4-bis-O- (p-ethyloxycarbonylbenzylidene) -D-sorbitol, 1,3: 2, 4-bis-O- (p-isopropyloxycarbonylbenzylidene) -D-sorbitol, 1,3: 2,4-bis-O- (on-propyloxycarbonylbenzylidene) -D-sorbitol, 1,3: 2,4-bis-O- (on-butylbenzylidene) -D-sorbitol, 1,3: 2,4-bis-O- (o-chlorobenzylidene) -D-sorbitol, 1,3: 2, 4-bis-O- (p-chlorobenzylidene) -D-sorbitol, 1,3: 2,4-bis-O-[(5,6,7,8, -tetrahydro-1-naphthalene) -1-methylene ] D-sorbitol, 1,3: 2,4-bis-O-[(5,6,7,8, -tetrahydro-2-naphthalene) -1-methylene] -D-sorbitol, 1,3-O-benzylidene -2,4-Op-methylbenzylidene-D-sorbitol, 1,3-Op-methylbenzylidene-2,4-O-benzylidene-D-sorbitol, 1,3-O-benzylidene-2,4 -Op-ethylbenzylidene-D-sorbitol, 1,3-O-p-ethylbenzylidene-2,4-O-benzylidene-D-sorbitol, 1,3-O-benzylidene-2,4-O-p -Chlorbenzylidene-D-sorbitol, 1,3-O-p-chlorobenzylidene-2,4-O-benzylidene-D-sorbitol, 1,3-O-benzylidene-2,4-O- (2,4- Zimechi Benzylidene) -D-sorbitol, 1,3-O- (2,4-dimethylbenzylidene) -2,4-O-benzylidene-D-sorbitol, 1,3-O-benzylidene-2,4-O- (3 , 4-Dimethylbenzylidene) -D-sorbitol, 1,3-O- (3,4-dimethylbenzylidene) -2,4-O-benzylidene-D-sorbitol, 1,3-Op-methyl-benzylidene- 2,4-O-p-ethylbenzylidenesorbitol, 1,3-p-ethyl-benzylidene-2,4-p-methylbenzylidene-D-sorbitol, 1,3-Op-methyl-benzylidene-2,4 -O-p-chlorobenzylidene-D-sorbitol, 1,3-O-p-chloro-benzylidene-2,4-Op-methylbenzylidene-D-sorbitol Cetal compound, sodium 2,2′-methylene-bis- (4,6-di-tert-butylphenyl) phosphate, aluminum bis [2,2′-methylene-bis- (4-6-di-tert-butylphenyl) ) Phosphate], sodium 2,2-methylenebis (4,6-di-tert-butylphenyl) phosphate, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, undecanoic acid, lauric acid, tridecanoic acid, myristic acid Acids, fatty acids such as pentadecanoic acid, palmitic acid, margaric acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, montanic acid, fatty acid amides such as oleic acid amide, erucic acid amide, stearic acid amide, hebenic acid amide, stearin Magnesium oxide, zinc stearate, calcium stearate Fatty acid metal salts such as calcium, inorganic particles such as silica, talc, kaolin and calcium carbide, higher fatty acid esters such as glycerol and glycerol monoester, and the like.

  In the present invention, fatty acid amides such as oleic acid amide, erucic acid amide, stearic acid amide, and hebenic acid amide, and fatty acid metal salts such as magnesium stearate, zinc stearate, and calcium stearate are used for improving transparency and rigidity. Particularly preferred.

  As specific examples of the crystal nucleating agent (C), the trade name “Gellall D” series of Shin Nippon Rika Co., Ltd., the trade name “Adekastab” of Asahi Denka Kogyo Co., Ltd., and the trade name “Millad” of Milliken Chemical Co., Ltd. ”,“ Hyperform ”, trade name“ IRGACLEAR ”of BASF Co., Ltd., etc. In addition, as a master batch of crystal nucleating agent, trade name“ Rike Master CN ”of Riken Vitamin Co., Ltd., Milliken Chemical Co., Ltd. Product name “Hyperform Concentrate” and the like. Among these, the products with the highest effect of improving transparency are trade names of “Milken Chemical Co., Ltd.” “Hyperform HPN-20E” and “Hyperform Concentrate HL3-4”, and Riken Vitamin Co., Ltd. 001 "," Rike Master CN-002 ".

<Olefin compatible resin (D)>
It is preferable that the resin layer (II) further contains an olefin-compatible resin (D) because the moisture resistance and transparency of the solar cell multilayer body of the present invention can be further improved.
Here, as the olefin-compatible resin (D), one kind of resin selected from the group consisting of petroleum resins, terpene resins, coumarone-indene resins, rosin resins, and hydrogenated derivatives thereof, or two or more kinds of resins. Resin. In the present invention, a petroleum resin or a terpene resin is preferably used for the reason described later.

Examples of the petroleum resin include alicyclic petroleum resins from cyclopentadiene or its dimer, aromatic petroleum resins from the C9 component, and the like.
Examples of the terpene resin include terpene-phenol resins from β-pinene.
Examples of the coumarone-indene resin include a coumarone-indene copolymer and a coumarone-indene-styrene copolymer.
Examples of the rosin resin include rosin resins such as gum rosin and wood rosin, and esterified rosin resins modified with glycerin, pentaerythritol, and the like.

The olefin-compatible resin (D) is a hydrogenated derivative, particularly a hydrogenation rate (hereinafter referred to as “hereinafter referred to as“ hydrogenation derivative ”) from the viewpoints of compatibility, color tone, thermal stability, wet heat resistance and the like when mixed with the ethylene resin (B). The hydrogenation rate, which may be abbreviated as “hydrogenation rate” (determined from the ratio of unsaturated double bonds of the conjugated diene based on the phenyl group based on the ¹ H-NMR spectrum) is 95% or more, and the hydroxyl group, carboxyl group, It is preferable to use a hydrogenated petroleum resin or a hydrogenated terpene resin that does not substantially contain a polar group such as halogen or an unsaturated bond such as a double bond.

In the multilayer body for solar cell of the present invention, the softening temperature Ts (D) measured in accordance with JIS K2207 of the olefin compatible resin (D) is [in accordance with JIS K7121 of the ethylene-based resin (B). It is preferably not more than [crystallization peak temperature Tc (B) + 5 ° C.] measured at a cooling rate of 10 ° C./min in the differential scanning calorimetry measured, more preferably not more than [the Tc (B) + 3 ° C.]. More preferably, it is [the Tc (B) + 2 ° C.] or less. The lower limit of Ts (D) is 80 ° C. Here, since the upper limit of the softening temperature Ts (D) satisfies this condition, the degree of freedom of the molecular chain of the olefin-compatible resin (D) is high in the crystallization process of the ethylene-based resin (B). It is preferable because crystallization of the resin (B) is hardly inhibited, fine crystals are formed, and a multilayer body for a solar cell excellent in moisture resistance and transparency can be obtained. Further, if the lower limit of the softening temperature Ts (D) of the olefin-compatible resin (D) is 80 ° C. or higher, preferably 90 ° C. or higher, blocking of raw materials during molding, secondary processing, or transportation, This is preferable because bleed-out to the surface of the solar cell multilayer body hardly occurs during use.
The softening temperature Ts (D) of the olefin compatible resin (D) can be obtained mainly by selecting the molecular weight.

  Specific examples of the olefin-compatible resin (D) include Mitsui Chemical Co., Ltd. trade names “Hirez”, “PETROSIN”, and Arakawa Chemical Industries Ltd. trade names “Arkon”. ”, Yashara Chemical Co., Ltd. trade name“ Clearon ”, Idemitsu Kosan Co., Ltd. trade name“ I MARV ”, Tonex Co., Ltd. trade name“ Escorez ”, etc. .

<Cyclic olefin resin (E)>
It is preferable that the resin layer (II) further contains a cyclic olefin resin (E) because the transparency can be further improved.
The cyclic olefin resin (E) used in the present invention includes (i) a polymer obtained by hydrogenating a ring-opened (co) polymer of a cyclic olefin as necessary, (ii) an addition (co) polymer of a cyclic olefin, (Iii) Random copolymer of cyclic olefin and α-olefin such as ethylene and propylene, (iv) The above (i) to (iii) are treated with maleic anhydride, maleic acid, itaconic anhydride, itaconic acid, (meth) Examples thereof include a graft copolymer modified with a modifier of unsaturated carboxylic acid such as acrylic acid or its anhydride. These may be used alone or in combination of two or more.

  The glass transition temperature (Tg) of the cyclic olefin-based resin (E) is preferably 50 to 110 ° C, more preferably 60 to 90 ° C, and further preferably 65 to 85 ° C. Here, it is preferable if the glass transition temperature (Tg) is within this range, since the transparency of the multilayer body for solar cells of the present invention can be improved without significantly reducing the heat resistance and workability.

  Since the cyclic olefin resin (E) has low compatibility with the ethylene resin (B) constituting the resin layer (II), the average refractive index at room temperature is 1.51 to 1 in consideration of transparency. .54, more preferably 1.515 to 1.535, and the absolute value of the difference from the average refractive index of the ethylene-based resin (B) used is 0.01 or less. Preferably, it is 0.005 or less, more preferably 0.003 or less. Here, if the absolute value of the average refractive index difference is within this range, it is preferable because the transparency can be improved without being greatly influenced by the dispersion diameter of the cyclic olefin resin (E) in the resin layer (II). . The average refractive index can be measured using a known method, for example, an Abbe refractometer.

  Specific examples of the cyclic olefin-based resin (E) include the product name “ZEONOR” of Nippon Zeon Co., Ltd., the product name “APEL” of Mitsui Chemicals Co., Ltd., and Polyplastics Co., Ltd. An example of the product name is “TOPAS”. The cyclic olefin resin (E) is disclosed in, for example, JP-A-60-168708, JP-A-61-115916, JP-A-61-271308, JP-A-61-252407. It can also be produced according to the known methods described.

<Resin layer (II)>
The resin layer (II) in the multilayer body for solar cell of the present invention is a resin layer containing the ethylene resin (B) and the crystal nucleating agent (C).

  The content of the ethylene resin (B) in the resin layer (II) is usually 30% by mass or more, preferably 30 to 99.9% by mass, and more preferably 40 to 85% by mass. preferable. Here, it is preferable that the ethylene-based resin (B) is within the above range because both moisture resistance and transparency can be achieved.

  Next, the content of the crystal nucleating agent (C) in the resin layer (II) can be appropriately determined within a range where transparency and moisture resistance are good, but is 0.01 to 3.0 mass. %, More preferably 0.03% by mass or more and 2.0% by mass or less, and further preferably 0.05% by mass or more and 1.0% by mass or less. Here, if the crystal nucleating agent (C) is within this range, there is no significant decrease in transparency due to interfacial scattering due to excessive addition, and the transparency and moisture resistance of the solar cell multilayer body of the present invention are improved. This is preferable.

  Next, the content of the olefin compatible resin (D) in the resin layer (II) is preferably 0 to 40% by mass, more preferably 10 to 30% by mass, and 10 to 25% by mass. It is particularly preferred that Here, if the olefin-compatible resin (D) is within the above range, there is no significant bleed to the surface or a significant decrease in mechanical properties, and the transparency and moisture resistance of the solar cell multilayer body of the present invention are further improved. This is preferable.

  Next, the content of the cyclic olefin resin (E) in the resin layer (II) is preferably 0 to 45% by mass, more preferably 15 to 40% by mass, and 20 to 35% by mass. It is particularly preferred that Here, it is preferable that the cyclic olefin-based resin (E) is within the above range because the transparency can be further improved without significantly reducing the moisture resistance.

  In the present invention, the thickness of the resin layer (II) is not particularly limited, but is preferably 0.01 to 0.30 mm from the viewpoint of the balance between moisture resistance, transparency and rigidity. It is more preferably 0.03 to 0.25 mm, and further preferably 0.05 to 0.15 mm.

<Other ingredients>
[Other resins]
In addition, the resin layer (I) and the resin layer (II) constituting the solar cell multilayer body of the present invention have various characteristics (flexibility, rigidity, heat resistance, transparency within the scope of the present invention). Resin layer (I), the resin layer (I) other than the silane-modified ethylene resin (A) and polyethylene resin (F) for the purpose of further improving the properties, adhesiveness, etc. If II), other resins other than the ethylene-based resin (B), the olefin-compatible resin (D), and the cyclic olefin-based resin (E) can be mixed. Here, as other resins, for example, other polyolefin resins and various elastomers (olefins, styrenes, etc.), polar groups such as carboxyl groups, amino groups, imide groups, hydroxyl groups, epoxy groups, oxazoline groups, thiol groups, etc. Examples thereof include a resin modified with a group.

[Additive]
Moreover, various additives can be added to the resin layer (I) and / or the resin layer (II) constituting the multilayer body for solar cell of the present invention, if necessary. Examples of the additive include a silane coupling agent, an antioxidant, an ultraviolet absorber, a weathering stabilizer, a light diffusing agent, a nucleating agent, a pigment (for example, a white pigment), a flame retardant, and a discoloration preventing agent. . In the present invention, it is preferable that at least one additive selected from an antioxidant, an ultraviolet absorber, and a weathering stabilizer is added for reasons described later.

(Silane coupling agent)
Silane coupling agents are useful for improving adhesion to protective materials for sealing materials (glass, resin front sheets, back sheets, etc.) and solar cell elements, such as vinyl groups, acryloxy groups, Examples thereof include compounds having a hydrolyzable group such as an alkoxy group together with an unsaturated group such as a methacryloxy group, an amino group, and an epoxy group. Specific examples of the silane coupling agent include N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane, N- (β-aminoethyl) -γ-aminopropylmethyldimethoxysilane, and γ-aminopropyltriethoxy. Examples include silane, γ-glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, and the like. When added, γ-glycidoxypropyltrimethoxysilane or γ-methacryloxypropyltrimethoxysilane is preferably used because of good adhesiveness and little discoloration such as yellowing. The addition amount of the silane coupling agent is usually about 0.0 to 5.0 parts by mass with respect to 100 parts by mass of the resin composition constituting each resin layer. Similarly to the silane coupling agent, A coupling agent such as an organic titanate compound can also be used effectively, but it is preferably not added in the present invention.

(Antioxidant)
As the antioxidant, various commercially available products can be applied, and various types such as monophenol type, bisphenol type, polymer type phenol type, sulfur type and phosphite type can be mentioned. Examples of monophenols include 2,6-di-tert-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-tert-butyl-4-ethylphenol, and the like. Examples of bisphenols include 2,2′-methylene-bis- (4-methyl-6-tert-butylphenol), 2,2′-methylene-bis- (4-ethyl-6-tert-butylphenol), 4,4 '-Thiobis- (3-methyl-6-tert-butylphenol), 4,4'-butylidene-bis- (3-methyl-6-tert-butylphenol), 3,9-bis [{1,1-dimethyl- 2- {β- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy} ethyl} 2,4,9,10-tetraoxaspiro] 5,5-undecane and the like.

  Examples of the high molecular phenolic group include 1,1,3-tris- (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3 , 5-di-tert-butyl-4-bidoxybenzyl) benzene, tetrakis- {methylene-3- (3 ', 5'-di-tert-butyl-4'-hydroxyphenyl) propionate} methane, bis { (3,3'-bis-4'-hydroxy-3'-tert-butylphenyl) butyric acid} glycol ester, 1,3,5-tris (3 ', 5'-di-tert-butyl-4 '-Hydroxybenzyl) -s-triazine-2,4,6- (1H, 3H, 5H) trione, triphenol (vitamin E) and the like.

  Examples of sulfur-based compounds include dilauryl thiodipropionate, dimyristyl thiodipropionate, and distearyl thiopropionate.

  Examples of the phosphite system include triphenyl phosphite, diphenylisodecyl phosphite, phenyl diisodecyl phosphite, 4,4′-butylidene-bis (3-methyl-6-tert-butylphenyl-di-tridecyl) phosphite, Crick neopentanetetrayl bis (octadecyl phosphite), tris (mono and / or di) phenyl phosphite, diisodecyl pentaerythritol diphosphite, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10- Oxide, 10- (3,5-di-tert-butyl-4-hydroxybenzyl) -9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 10-decyloxy-9,10 -Dihydro-9-oxa-10-fo Phaphenanthrene, cyclic neopentanetetraylbis (2,4-di-tert-butylphenyl) phosphite, cyclic neopentanetetraylbis (2,6-di-tert-methylphenyl) phosphite, 2 , 2-methylenebis (4,6-tert-butylphenyl) octyl phosphite.

  In the present invention, phenol-based and phosphite-based antioxidants are preferably used in view of the effect of the antioxidant, thermal stability, economy, and the like, and it is more preferable to use both in combination. The addition amount of the antioxidant is usually about 0.1 to 1.0 part by mass with respect to 100 parts by mass of the resin composition constituting each resin layer, and 0.2 to 0.5 part by mass is added. It is preferable.

(UV absorber)
Examples of the ultraviolet absorber include various types such as benzophenone-based, benzotriazole-based, triazine-based, salicylic acid ester-based, and various commercially available products can be applied. Examples of the benzophenone-based UV absorber include 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-2′-carboxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2-hydroxy-4-n. -Dodecyloxybenzophenone, 2-hydroxy-4-n-octadecyloxybenzophenone, 2-hydroxy-4-benzyloxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone, 2-hydroxy-5-chlorobenzophenone, 2, , 4-dihydroxybenzophenone, 2,2′-dihydroxy-4-methoxybenzophenone, 2,2′-dihydroxy-4,4′-dimethoxybenzophenone, 2,2 ′, 4,4′-tetrahydroxybenzophenone and the like. .

  The benzotriazole ultraviolet absorber is a hydroxyphenyl-substituted benzotriazole compound, for example, 2- (2-hydroxy-5-methylphenyl) benzotriazole, 2- (2-hydroxy-5-t-butylphenyl) Benzotriazole, 2- (2-hydroxy-3,5-dimethylphenyl) benzotriazole, 2- (2-methyl-4-hydroxyphenyl) benzotriazole, 2- (2-hydroxy-3-methyl-5-t- Butylphenyl) benzotriazole, 2- (2-hydroxy-3,5-di-t-amylphenyl) benzotriazole, 2- (2-hydroxy-3,5-di-t-butylphenyl) benzotriazole and the like. It is done. Examples of triazine ultraviolet absorbers include 2- [4,6-bis (2,4-dimethylphenyl) -1,3,5-triazin-2-yl] -5- (octyloxy) phenol, 2- ( 4,6-diphenyl-1,3,5-triazin-2-yl) -5- (hexyloxy) phenol and the like. Examples of salicylic acid esters include phenyl salicylate and p-octylphenyl salicylate.

  The addition amount of the ultraviolet absorber is usually about 0.01 to 2.0 parts by mass with respect to 100 parts by mass of the resin composition constituting each resin layer, and 0.05 to 0.5 parts by mass is added. It is preferable.

(Light stabilizer)
A hindered amine light stabilizer is suitably used as a weather stabilizer that imparts weather resistance in addition to the above ultraviolet absorber. A hindered amine light stabilizer does not absorb ultraviolet rays like an ultraviolet absorber, but exhibits a remarkable synergistic effect when used together with an ultraviolet absorber. There are some which function as a light stabilizer other than hindered amines, but they are often colored and are not preferable for the multilayer body for solar cell of the present invention.

  Examples of hindered amine light stabilizers include dimethyl succinate-1- (2-hydroxyethyl) -4-hydroxy-2,2,6,6-tetramethylpiperidine polycondensate, poly [{6- (1,1 , 3,3-tetramethylbutyl) amino-1,3,5-triazine-2,4-diyl} {(2,2,6,6-tetramethyl-4-piperidyl) imino} hexamethylene {{2, 2,6,6-tetramethyl-4-piperidyl} imino}], N, N′-bis (3-aminopropyl) ethylenediamine-2,4-bis [N-butyl-N- (1,2,2, 6,6-pentamethyl-4-piperidyl) amino] -6-chloro-1,3,5-triazine condensate, bis (2,2,6,6-tetramethyl-4-piperidyl) separate, 2- (3 , 5-Di-tert-4- Mud alkoxybenzylacetic) -2-n-butyl malonic acid bis (1,2,2,6,6-pentamethyl-4-piperidyl) and the like.

  The amount of the hindered amine light stabilizer added is usually about 0.01 to 0.5 parts by mass and 0.05 to 0.3 parts by mass with respect to 100 parts by mass of the resin composition constituting each resin layer. It is preferable to add a part.

[Multilayer for solar cells]
The multilayer body for solar cell of the present invention has excellent moisture resistance, and has a water vapor transmission rate of 3.0 g / (m ² · 24 hours) measured at a total thickness of 0.3 mm, a temperature of 40 ° C., and a relative humidity of 90%. The following is preferable. In this invention, it is more preferable that it is 2.0 g / (m < ² > * 24 hours) or less from viewpoints, such as durability and long-term reliability of the solar cell module produced using the multilayer body for solar cells. further preferably .0g / (m ² · 24 hr) or less, 0.5g / (m ² · 24 hours) and particularly preferably less. Such excellent moisture resistance in the present invention is mainly due to the combination of the ethylene resin (B) and the crystal nucleating agent (C), and also the olefin compatible resin (D) and / or the cyclic olefin resin. This can be achieved by adding (E). The water vapor transmission rate can be measured by various known methods. In the present invention, the temperature is 40 ° C. using PERMATRAN W 3/31 manufactured by MOCON in accordance with JIS K7129B. The water vapor transmission rate of a multilayer sheet having a total thickness of 0.3 mm was measured under the condition of 90% relative humidity.

  The multilayer body for solar cell of the present invention can be appropriately adjusted in its flexibility and rigidity in consideration of the shape, thickness, installation location, etc. of the applied solar cell. For example, handling property when the solar cell multilayer body of the present invention is collected in the form of a sheet, prevention of blocking between sheet surfaces, or weight reduction in a solar cell module (usually about 3 mm, thin film glass (1.1 mm The degree of storage elasticity (E ′) at a vibration frequency of 10 Hz and a temperature of 20 ° C. in the dynamic viscoelasticity measurement is preferably 100 to 1000 MPa. 250 to 900 MPa, more preferably 300 to 700 MPa, and particularly preferably 400 to 600 MPa. The storage elastic modulus (E ′) can be obtained by measuring a predetermined temperature range at a vibration frequency of 10 Hz using a dynamic viscoelasticity measuring apparatus and obtaining a value at a temperature of 20 ° C.

  Since the multilayer body for solar cell of the present invention has a multilayer structure having the resin layer (I) and the resin layer (II) as at least one of the outermost layers, characteristics required for the surface layer such as adhesion and flexibility It is possible to balance the properties required for the entire multilayer body such as moisture resistance and handling properties (rigidity) in a well-balanced manner.

  For example, to explain flexibility and handling properties (rigidity) as an example, the multilayer body for solar cell of the present invention employs a soft layer as the resin layer (I) and a hard layer as the resin layer (II), and these thicknesses By appropriately adjusting the ratio, it is possible to balance both flexibility and handling properties (rigidity) in a balanced manner. The multilayer body for solar cell of the present invention may have a laminated structure of two or more layers of the resin layer (I) and the resin layer (II). However, curling prevention (maintaining flatness) and film formation as a multilayer body From the viewpoint of properties, a symmetrical configuration such as a resin layer (I) / resin layer (II) / resin layer (I), in other words, a soft layer / a hard layer / a soft layer, two-layer / three-layer configuration is preferable.

  The soft layer is not particularly limited, but a layer having a storage elastic modulus (E ′) at a vibration frequency of 10 Hz and a temperature of 20 ° C. in dynamic viscoelasticity measurement is preferably 100 MPa or less, more preferably 5 to 50 MPa. The hard layer is a layer having a storage elastic modulus (E ′) of preferably more than 100 MPa, more preferably 200 to 3000 MPa, still more preferably 500 to 2000 MPa. By employing such a laminated structure, when the solar cell multilayer body of the present invention is used as, for example, a solar cell sealing material, the solar cell element protection (cushioning property) and the entire sealing material handling property It is preferable because compatibility (such as elastic modulus at room temperature) can be realized relatively easily.

  The total light transmittance at a total thickness of 0.3 mm of the multilayer body for solar cell of the present invention is applied to the type of solar cell to be applied, for example, an amorphous thin-film silicon type or a portion that does not block sunlight reaching the solar electronic device. In this case, it may not be considered as important, but it is preferably 85% or more, preferably 88% or more in consideration of the photoelectric conversion efficiency of the solar cell and workability when stacking various members. More preferably, it is more preferably 90% or more. The total light transmittance can be measured by various known methods. However, in the present invention, “reflective / transmittance” manufactured by Murakami Color Research Laboratory Co., Ltd. is used in accordance with JIS K7105. The total light transmittance of a multilayer sheet having a total thickness of 0.3 mm was measured using a “meter”.

The multilayer body for solar cell of the present invention can easily form a solar cell module, can omit the crosslinking step, and has excellent transparency, moisture resistance, sealing property, handling property (rigidity), etc. It is suitably used as a material. In order to satisfy these characteristics at the same time, when a solar cell multilayer body having a total thickness of 0.3 mm is measured, the storage elastic modulus (E ′) at a vibration frequency of 10 Hz and a temperature of 20 ° C. in the dynamic viscoelasticity measurement is 300 to 700 MPa. The water vapor transmission rate measured at a temperature of 40 ° C. and a relative humidity of 90% is preferably 3.0 g / (m ² · 24 hours) or less, and the total light transmittance is preferably 85% or more. More preferably, the water vapor permeability measured at a vibration frequency of 10 Hz, a storage elastic modulus (E ′) at a temperature of 20 ° C. of 400 to 600 MPa, a temperature of 40 ° C. and a relative humidity of 90% in the dynamic viscoelasticity measurement is 2.0 g / ( m ² · 24 hours) or less, and the total light transmittance is 87% or more, more preferably, the storage elastic modulus (E ′) at a vibration frequency of 10 Hz and a temperature of 20 ° C. in the dynamic viscoelasticity measurement is 400 to 600 MPa, The water vapor transmission rate measured at a temperature of 40 ° C. and a relative humidity of 90% is 1.0 g / (m ² · 24 hours) or less, and the total light transmittance is 88% or more.

  The heat resistance of the multilayer body for solar cell of the present invention is affected by various properties of the resin used for the resin layer (I) and the resin layer (II) (crystal melting peak temperature, crystal melting heat amount, MFR, molecular weight, etc.). In general, a solar cell module is heated to about 85 to 90 ° C. by heat generated during power generation or radiant heat of sunlight, but if the crystal melting peak temperature is 100 ° C. or higher, the heat resistance of the multilayer body for solar cell of the present invention is increased. It is preferable because the property can be secured.

  The total thickness of the multilayer body for solar cells of the present invention is not particularly limited, but is usually about 0.03 to 1.0 mm, from the viewpoint of transparency, moisture resistance, handling properties, etc. Preferably, it is used in a sheet form of 0.10 to 0.75 mm.

[Method for producing solar cell multilayer body]
Next, the manufacturing method of the multilayer body for solar cells of this invention is demonstrated.
As a method for forming a sheet-like multilayer for a solar cell, a known method, for example, an extrusion casting method using a T-die having a melt mixing facility such as a single screw extruder, a multi-screw extruder, a Banbury mixer, a kneader, etc. A calendering method, an inflation method, and the like can be employed and are not particularly limited. In the present invention, an extrusion casting method using a T die is preferably used from the viewpoints of handling properties, productivity, and the like. The molding temperature in the extrusion casting method using a T die is appropriately adjusted depending on the flow characteristics and film forming properties of the resin composition constituting each resin layer, but is generally 130 to 280 ° C, preferably 150 to 250 ° C. It is. In addition, as a multilayering method, a known method such as a co-extrusion method, an extrusion lamination method, a heat lamination method, a dry lamination method, or the like can be used, but in the present invention, handling property, productivity, etc. From the viewpoint of the above, a coextrusion method is preferably used. In the coextrusion method, various multilayer die can be selected, and examples thereof include a feed block method and a multi-manifold method. In addition, a dumbbell base, a capsule base, or the like can be used as appropriate for the purpose of preventing the trimming efficiency of each resin layer and the decrease in transparency during regeneration addition.

  In the multilayer body for solar cell of the present invention produced by the above production method, the thickness ratio with respect to the total thickness of the resin layer (II) is preferably 10% or more and 90% or less, and 20% or more and 60% or less. It is more preferable that it is 25% or more and 45% or less. Here, it is preferable if the thickness ratio of the resin layer (II) is within the above range because a multilayer body for solar cell excellent in the balance between moisture resistance, rigidity and transparency can be obtained. Moreover, since the multilayer body for solar cells of the present invention is excellent in rigidity at room temperature, for example, when used in a flexible type solar cell module, it can impart rigidity (waist), and the rigid type solar cell module When used, thin glass (for example, 1.1 mm) can be applied, or a structure such as glassless can be applied, and weight reduction can be expected.

  In addition, the multilayer body for solar cell of the present invention preferably has a two-layer / three-layer structure of resin layer (I) / resin layer (II) / resin layer (I) as described above. It is also possible to adopt other laminated structures for the purpose of improvement or appearance adjustment (improvement of warp or curl, etc.). For example, resin layer (I) (with additive) / resin layer (I) (without additive) / resin layer (II), resin layer (I) (with additive A) / resin layer (I) ( (Including additive B) (additives A and B have different additive formulations) / resin layer (II), resin layer (I) ′ / resin layer (I) ″ (resin layer (I) ′ and (I ) '' Is different in storage modulus (E ′) and mixing ratio of additives) / resin layer (II), resin layer (I) / resin layer (II) ′ / resin layer (II) ″ (resin layer) (II) ′ and (II) ″ have different storage elastic moduli (E ′) and mixing ratios of additives (three types and three layers), resin layer (I) / adhesive layer / resin layer (II) / adhesion Layer / resin layer (II) (adhesive layer is an adhesive layer of resin layer (I) and resin layer (II)), resin layer (I) / recycled layer / resin layer (II) / recycled layer / resin layer (I ) And resin layer (I) / reproduction layer / Examples of the resin layer (II) / reproduction layer / resin layer (II) include three types and five layers. Here, to the reproduction layer, a scroll generated by trimming ears or adjusting the width of the product generated when the multilayer body for solar cell of the present invention is formed can be added. In the present invention, in order not to lower the moisture resistance, transparency, rigidity, etc., which are the main functions of the resin layer (II), the resin layer (II) has an ear trimming or product It is preferable to set and add a reproduction layer without adding as much as possible the scroll generated by the width adjustment (slit).

  The method of mixing various additives such as antioxidants, ultraviolet absorbers, weathering stabilizers, etc. used in the multilayer body for solar cells of the present invention may be dry-blended with the resin in advance and then supplied to the hopper. These materials may be melt-mixed to produce pellets and then supplied, or a master batch in which only the additive is previously concentrated in the resin may be produced and supplied. Moreover, on the surface and / or the back surface of the solar cell multilayer body of the present invention obtained in the form of a sheet, if necessary, the sheet is prevented from blocking between sheets and the solar cell element is sealed. Embossing and various irregularities (cone, pyramid shape, hemispherical shape, etc.) may be performed for the purpose of improving the handleability and ease of bleeding.

  Furthermore, when producing the multilayer body for solar cells of the present invention, another base film (for example, stretched polyester film (OPET), stretched polypropylene film (OPP) or ETFE (tetrafluoroethylene / ethylene copolymer)). , PVF (polyvinyl fluoride), PVDF (polyvinylidene fluoride), acrylic weather-resistant films, etc.) and extrusion lamination, co-extrusion, sand lamination, etc. may be used for lamination. By laminating the solar cell multilayer body and various substrate films of the present invention, it is possible to adjust the required characteristics and economy relatively easily according to the improvement in handling properties and the lamination ratio.

[Solar cell module]
The multilayer body for solar cell of the present invention is used as a member for solar cell, and its part is not particularly limited, but mainly as a solar cell sealing material that adheres to and protects the solar cell element. It is also used for parts that are not in close contact with the solar cell element for the purpose of adjusting flexibility, rigidity, curl, thickness and dielectric breakdown voltage of the part and the solar cell module as a whole. Here, as a specific example of the portion that is not in close contact with the solar cell element, for example, the constituent layer of the upper protective material of the solar cell module such as the upper protective material / sealing material / solar cell element / sealing material / lower protective material As the outermost surface layer / multilayer body for solar cell of the present invention / barrier layer, outermost surface layer / barrier layer / multilayer body for solar cell of the present invention, outermost surface layer / multilayer body for solar cell of the present invention, outermost surface Layer / multilayer body for solar cell of the present invention / barrier layer / multilayer body for solar cell of the present invention, and the like. Back layer, other polyolefin layer (such as CPP) / multilayer body for solar cell of the present invention / barrier layer / outermost layer, other polyolefin layer (such as CPP) / barrier layer / multilayer body for solar cell of the present invention / Back layer and other polyolefin layers (CPP, etc.) A multilayer body / top back surface layer of the solar cell and the like. Further, when the solar cell multilayer body of the present invention is used in a portion that does not adhere to the solar cell element, the solar cell sealing material that adheres to and protects the solar cell element includes the solar cell multilayer body of the present invention, Alternatively, commercially available EVA or ionomer type solar cell encapsulants can be used. Here, a solar cell module manufactured using the solar cell multilayer body of the present invention as a solar cell sealing material that adheres to and protects the solar cell element will be described.

  A solar cell module can be manufactured by fixing the solar cell element with a front sheet and a back sheet, which are upper and lower protective materials, using the multilayer body for solar cell of the present invention. As such a solar cell module, various types can be exemplified, and preferably, the solar cell multilayer body of the present invention is used as a sealing material, and an upper protective material, a solar cell element, and a lower portion are used. The solar cell module produced using the protective material is mentioned. Specifically, the present invention is applied from both sides of the solar cell element such as upper protective material / sealing material / solar cell element / sealing material / lower protective material. The structure sandwiched between the solar cell multilayer bodies of the invention (see FIG. 1), the structure in which the sealing material and the upper protective material are formed on the solar cell element formed on the inner peripheral surface of the lower protective material. A solar cell element formed on the inner peripheral surface of the upper protective material, for example, a sealing material and a lower protective material are formed on an amorphous solar cell element formed by sputtering or the like on a fluororesin-based transparent protective material The thing of the structure to let you It is below. In the solar cell module using the solar cell multilayer body of the present invention, when the sealing material is used at two or more sites, the solar cell multilayer body of the present invention may be used at all sites. Or the multilayer body for solar cells of the present invention may be used in only one part. Further, when the sealing material is used in two or more parts, the resin layer (I) and the resin layer (II) constituting the solar cell multilayer body of the present invention used in each part are constituted. The composition of the resin composition and the thickness ratio of the resin layer (I) and the resin layer (II) in the multilayer body may be the same or different. In any case, when the solar cell element is sealed by producing the solar cell module so that the resin layer (I) side of the solar cell multilayer body of the present invention is in contact with the solar cell element side. It is preferable because sufficient adhesion and sealing properties can be obtained.

  Examples of the solar cell element disposed and wired between the sealing materials include, for example, III- such as single crystal silicon type, polycrystalline silicon type, amorphous silicon type, gallium-arsenide, copper-indium-selenium, and cadmium-tellurium. Group V and II-VI compound semiconductor types, dye-sensitized types, organic thin film types, and the like can be given.

  About each member which comprises the solar cell module produced using the multilayer body for solar cells of this invention, although it does not specifically limit, As an upper protective material, glass, an acrylic resin, a polycarbonate, polyester, for example And a single layer or multilayer protective material of a plate material such as a fluorine-containing resin or a film. The lower protective material is a single layer or multilayer sheet such as metal or various thermoplastic resin films, for example, metals such as tin, aluminum and stainless steel, inorganic materials such as glass, polyester, inorganic vapor deposition polyester, fluorine-containing resin. And a single-layer or multilayer protective material such as polyolefin. The surface of these upper and / or lower protective materials may be subjected to a known surface treatment such as a primer treatment or a corona treatment in order to improve the adhesion with the solar cell multilayer body of the present invention or other members. it can.

  The upper protective material / sealing material (resin layer (I) / resin layer (II) / resin layer (I)) / solar cell element described above for the solar cell module produced using the multilayer body for solar cell of the present invention / Sealant (resin layer (I) / resin layer (II) / resin layer (I)) / Example of a structure sandwiched between both sides of a solar cell element by a sealant, such as a lower protective material To do. As shown in FIG. 1, the transparent substrate 10 and the solar cell multilayer body of the present invention (resin layer (I) / resin layer (II) / resin layer (I)) are used in this order from the sunlight receiving side. A material 12A, solar cell elements 14A and 14B, a solar cell multilayer body (resin layer (I) / resin layer (II) / resin layer (I)) 12A, and a back sheet 16 are laminated. Further, a junction box 18 (a terminal box for connecting wiring for taking out electricity generated from the solar cell element) is adhered to the lower surface of the back sheet 16. The solar cell elements 14A and 14B are connected by a wiring 20 in order to conduct the generated current to the outside. The wiring 20 is taken out through a through hole (not shown) provided in the back sheet 16 and connected to the junction box 18.

  As a manufacturing method of the solar cell module, a known manufacturing method can be applied, and it is not particularly limited, but in general, an upper protective material, a sealing material, a solar cell element, a sealing material, a lower protective material. And a step of vacuum-sucking them and heat-pressing them. Also, batch type manufacturing equipment, roll-to-roll type manufacturing equipment, and the like can be applied.

  The solar cell module produced by using the solar cell multilayer body of the present invention is a small solar cell represented by a mobile device, a large solar cell installed on a roof or a roof, depending on the type and module shape of the applied solar cell. The battery can be applied to various uses regardless of whether it is indoors or outdoors.

  Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto. In addition, the various measured values and evaluation about the sheet | seat displayed in this specification were performed as follows. Here, the flow direction of the sheet from the extruder is called the vertical direction, and the orthogonal direction is called the horizontal direction.

(1) Crystal melting peak temperature (Tm)
Using a differential scanning calorimeter manufactured by PerkinElmer Co., Ltd., trade name “Pyris1 DSC”, according to JIS K7121, about 10 mg of sample was heated from −40 ° C. to 200 ° C. at a heating rate of 10 ° C./min. After holding at 200 ° C. for 1 minute, the temperature was lowered to −40 ° C. at a cooling rate of 10 ° C./min, and again from the thermogram measured when the temperature was raised to 200 ° C. at a heating rate of 10 ° C./min. (Tm) (° C.) was determined.

(2) Crystallization peak temperature (Tc)
Using a differential scanning calorimeter manufactured by PerkinElmer Co., Ltd., trade name “Pyris1 DSC”, according to JIS K7121, about 10 mg of sample was heated from −40 ° C. to 200 ° C. at a heating rate of 10 ° C./min. After maintaining at 200 ° C. for 1 minute, the crystallization peak temperature (Tc) (° C.) was determined from the thermogram measured when the temperature was lowered to −40 ° C. at a cooling rate of 10 ° C./min.

(3) Heat of crystal melting (ΔHm)
Using a differential scanning calorimeter manufactured by PerkinElmer Co., Ltd., trade name “Pyris1 DSC”, according to JIS K7122, about 10 mg of sample was heated from −40 ° C. to 200 ° C. at a heating rate of 10 ° C./min. After holding at 200 ° C. for 1 minute, the temperature was lowered to −40 ° C. at a cooling rate of 10 ° C./min, and again from the thermogram measured when the temperature was raised to 200 ° C. at a heating rate of 10 ° C./min ( ΔHm) (J / g) was determined.

(4) Softening temperature (Ts)
Based on JIS K2207, the softening temperature of the olefin compatible resin (E) was determined.

(5) Molecular weight distribution index (Mw / Mn)
A weight average molecular weight (Mw) and a number average molecular weight (Mn) were measured using a high temperature GPC system manufactured by Nippon Water Co., Ltd., and a molecular weight distribution index (Mw / Mn) was calculated.

(6) Transparency (total light transmittance)
Using a “reflection / transmittance meter” manufactured by Murakami Color Research Laboratory Co., Ltd., the total light transmittance of a multilayer sheet having a total thickness of 0.3 mm was measured according to JIS K7105. The results were described, and the results evaluated according to the following criteria were also shown.
(○) Total light transmittance is 85% or more (×) Total light transmittance is less than 85%

(7) Moisture resistance (water vapor transmission rate)
Using PERMATRAN W 3/31 manufactured by MOCON, the water vapor transmission rate of a multilayer sheet having a total thickness of 0.3 mm was measured under the conditions of a temperature of 40 ° C. and a relative humidity of 90% in accordance with JIS K7129B. The results were described, and the results evaluated according to the following criteria were also shown.
(◎) Water vapor transmission rate is 1.0 g / (m ² · 24 hours) or less (○) Water vapor transmission rate exceeds 1.0 g / (m ² · 24 hours) and 3.0 g / (m ² · ² hours) 24 hours) or less (x) Water vapor transmission rate exceeds 3.0 g / (m ² · 24 hours)

(8) Average refractive index Using an Atago Co., Ltd. Abbe refractometer, sodium D line (589 nm) was measured as a light source in accordance with JIS K7142.

(9) Vicat softening temperature Measured according to JIS K7206. That is, the temperature of the heat transfer medium is increased at a rate of 50 ° C./hour while applying a total load of 10 N (A method) through a needle-like indenter having a tip cross-sectional area of 1 mm ² placed perpendicular to the test piece in the heating bath, The temperature when the tip of the indenter entered 1 mm into the test piece was measured.

(10) Rigidity (Storage elastic modulus (E ′))
Using a dynamic viscoelasticity measuring machine manufactured by IT Measurement Co., Ltd., trade name “Viscoelastic Spectrometer DVA-200”, a sample (4 mm long, 60 mm wide) was subjected to a vibration frequency of 10 Hz, a strain of 0.1%, and a temperature increase. Measurement was made from −150 ° C. to 150 ° C. in the transverse direction at a speed of 3 ° C./min and 25 mm between chucks, and the storage elastic modulus (E ′) at 20 ° C. was determined from the obtained data. The results were described, and the results evaluated according to the following criteria were also shown.
(◎) The storage elastic modulus (E ′) at 20 ° C. is 300 MPa or more and 700 MPa or less (◯) The storage elastic modulus (E ′) at 20 ° C. is 100 MPa or more and less than 300 MPa, or more than 700 MPa and 1000 MPa or less. Yes (×) Storage elastic modulus (E ′) at 20 ° C. exceeds 1000 MPa

(11) Sealing property Using a vacuum laminator manufactured by NPC Corporation, trade name “LM30 × 30”, hot plate temperature: 150 ° C., processing time: 20 minutes (breakdown, vacuuming: 5 minutes) , Press: 5 minutes, pressure retention: 10 minutes), pressure bonding speed: under rapid conditions, in order from the hot plate side, 3 mm thick white plate glass (trade name: Solite, manufactured by Asahi Glass Co., Ltd.), 0.3 mm thick Multilayer sheet (sealing material), solar cell element (cell) having a thickness of 0.4 mm (manufactured by France Photowatt Co., Ltd., product name: 101 × 101 MM), multilayer sheet having a thickness of 0.3 mm (sealing material), thickness 0. The appearance of a solar cell module (size: 150 mm × 150 mm) produced by vacuum pressing 5 layers of 125 mm weather-resistant PET film (trade name: Lumirror X10S, manufactured by Toray Industries, Inc.) Evaluated by criteria.
(○) Multi-layer sheet is sufficiently wrapped around the solar cell element without any gaps (×) The multilayer sheet is not sufficiently wrapped around the solar cell element, and bubbles and floats are generated

(12) Heat resistance A multilayer sheet with a total thickness of 0.3 mm is stacked between a white plate glass (size: 75 mm length, 25 mm width) and an aluminum plate (size: length 120 mm, width 60 mm) with a thickness of 3 mm, and vacuum is applied. Using a press machine, a sample which was laminated and pressed at 150 ° C. for 15 minutes was prepared, and the sample was installed at an inclination of 60 ° C. in a constant temperature and humidity chamber of 85 ° C. and 85% RH. Was observed and evaluated according to the following criteria.
(○) Glass did not deviate from the initial reference position (×) Glass deviated from the initial reference position, or the sheet melted

<Materials used>
[Silane-modified ethylene resin (A)]
(A) -1; Silane-modified ethylene-octene random copolymer (Mitsubishi Chemical Co., Ltd., trade name: Linkron SL800N, density: 0.868 g / cm ³ , crystal melting peak temperature: 54 ° C. and 116 ° C., Heat of crystal fusion: 22 J / g and 4 J / g, storage elastic modulus (E ′) at 20 ° C .: 15 MPa, average refractive index: 1.4857, MFR (temperature: 190 ° C., load: 21.18 N): 1.7 g / 10min)
(A) -2; Silane-modified ethylene-hexene random copolymer (manufactured by Mitsubishi Chemical Corporation, trade name: Linkron XLE815N, density: 0.915 g / cm ³ , crystal melting peak temperature: 121 ° C., crystal melting heat quantity : 127 J / g, storage elastic modulus at 20 ° C. (E ′): 398 MPa, average refractive index: 1.5056, MFR (temperature: 190 ° C., load: 21.18 N): 0.5 g / 10 min)

[Ethylene resin (B)]
(B) -1; ethylene-butene-octene random copolymer (manufactured by Asahi Kasei Corporation, trade name: Creolex K4125, ethylene / 1-butene / 1-octene = 97.7 / 1.1 / 1.2 Mass% (99.1 / 0.6 / 0.3 mol%), density: 0.941 g / cm ³ , crystal melting peak temperature: 130 ° C., crystal melting heat amount: 183 J / g, crystallization peak temperature (Tc ( B)): 114 ° C., Mw / Mn: 3.12, Storage elastic modulus (E ′) at 20 ° C .: 1100 MPa, average refractive index: 1.5274, MFR (temperature: 190 ° C., load: 21.18 N): 2.5g / 10min)
(B) -2; ethylene-hexene random copolymer (manufactured by Ube Maruzen Polyethylene Co., Ltd., trade name: Umerit 2040FC, density: 0.918 g / cm ³ , crystal melting peak temperature: 121 ° C., crystal melting heat: 134 J / G, crystallization peak temperature (Tc (B)): 105 ° C., Mw / Mn: 2.80, storage elastic modulus (E ′) at 20 ° C .: 451 MPa, average refractive index: 1.5120, MFR (temperature: 190 ° C., load: 21.18 N): 5 g / 10 min)
(B) -3; ethylene-butene-octene random copolymer (manufactured by Asahi Kasei Co., Ltd., trade name: Creolex K4750, ethylene / 1-butene / 1-octene = 97.9 / 0.8 / 1.3 Mass% (99.3 / 0.4 / 0.3 mol%), density: 0.947 g / cm ³ , crystal melting peak temperature: 131 ° C., crystal melting heat amount: 181 J / g, crystallization peak temperature (Tc ( B)): 113 ° C., Mw / Mn: 2.87, storage elastic modulus (E ′) at 20 ° C .: 1478 MPa, average refractive index: 1.5300, MFR (temperature: 190 ° C., load: 21.18 N): 5g / 10min)
(B) -4; ethylene homopolymer (manufactured by Asahi Kasei Co., Ltd., trade name: Suntec HD F371, ethylene: 100 mass% (100 mol%), density: 0.944 g / cm ³ , crystal melting peak temperature: 131 ° C, heat of crystal fusion: 167 J / g, crystallization peak temperature (Tc (B)): 114 ° C, Mw / Mn: 4.72, storage elastic modulus (E ') at 20 ° C: 1218 MPa, MFR (temperature: 190) ° C, load: 21.18 N): 0.45 g / 10 min)

[Crystal nucleating agent (C)]
(C) -1; fatty acid metal salt (zinc stearate / 1,2-cyclohexanedicarboxylic acid calcium salt = 34/66 (mass ratio))

[Olefin compatible resin (D)]
(D) -1: Hydrogenated petroleum resin (Arakawa Chemical Industries, Ltd., trade name: Alcon P115, softening temperature Ts (D): 115 ° C.)
(D) -2; Hydrogenated petroleum resin (Arakawa Chemical Industries, Ltd., trade name: Alcon P140, softening temperature Ts (D): 140 ° C.)

[Cyclic olefin resin (E)]
(E) -1: Cyclic olefin resin (manufactured by Polyplastics Co., Ltd., trade name: TOPAS 9506F-04, glass transition temperature: 68 ° C., amorphous, average refractive index: 1.5287)

[Ethylene resin (F)]
(F) -1; ethylene-octene random copolymer (manufactured by Dow Chemical Co., Ltd., trade name: affinity EG8200G, density: 0.870 g / cm ³ , ethylene / 1-octene = 68/32% by mass (89 / 11 mol%), crystal melting peak temperature: 59 ° C., crystal melting heat amount: 49 J / g, Vicat softening temperature: 45 ° C., storage elastic modulus (E ′) at 20 ° C .: 14 MPa, average refractive index: 1.4856, MFR (temperature: 190 ° C., load: 21.18 N): 5 g / 10 min)
(F) -2; ethylene-octene block copolymer (manufactured by Dow Chemical Co., Ltd., trade name: Infuse 9000, density: 0.875 g / cm ³ , ethylene / 1-octene = 65/35% by mass ( 88/12 mol%), crystal melting peak temperature: 122 ° C., crystal melting heat amount: 44 J / g, storage elastic modulus (E ′) at 20 ° C .: 27 MPa, average refractive index: 1.4899, MFR (temperature: 190 ° C.) , Load: 21.18 N): 0.5 g / 10 min)

Example 1
(A) -1 and (F) -1 are mixed at a ratio of 30:70 using a φ40 mm co-directional twin-screw extruder, and resin layers (both outer layers from a two-kind, three-layer multi-manifold die) ( Extruded at a set temperature of 180 to 200 ° C. as I). At the same time, (B) -1 and (C) -1 are mixed at a mass ratio of 99.9: 0.1 using a φ40 mm co-directional twin-screw extruder and the resin layer (II ) At a set temperature of 200 to 230 ° C. Subsequently, the discharge amount of the molten resin is adjusted, and the coextruded sheet is rapidly cooled with a cast roll of about 20 ° C., so that the thickness of each layer is resin layer (I) / resin layer (II) / resin layer (I) = 0.1 / 0.1 / 0.1 (mm) and a multilayer sheet having a total thickness of 0.3 mm was obtained. The obtained multilayer sheet was evaluated for transparency, moisture resistance, heat resistance, and the like. The results are shown in Table 1.

(Example 2)
In Example 1, a multilayer sheet was obtained by the same method and thickness as in Example 1 except that (B) -1 in the resin composition constituting the resin layer (II) was changed to (B) -2. . The obtained multilayer sheet was evaluated for transparency, moisture resistance, heat resistance, and the like. The results are shown in Table 1.

(Example 3)
In Example 2, the same method as in Example 2 except that the resin composition constituting the resin layer (I) was changed from (A) -2 and (F) -1 to a mixing mass ratio of 5:95. A multilayer sheet having a thickness configuration was obtained. The obtained multilayer sheet was evaluated for transparency, moisture resistance, heat resistance, and the like. The results are shown in Table 1.

Example 4
In Example 2, except that the resin composition constituting the resin layer (I) was changed from (A) -1, (F) -1, and (F) -2 to a mixing mass ratio of 10: 85: 5. Obtained a multilayer sheet by the same method and thickness structure as in Example 2. The obtained multilayer sheet was evaluated for transparency, moisture resistance, heat resistance, and the like. The results are shown in Table 1.

(Example 5)
In Example 1, the resin composition constituting the resin layer (II) is a ratio of (B) -1, (C) -1, and (D) -1 in a mixing mass ratio of 79.9: 0.1: 20. A multilayer sheet was obtained by the same method and thickness structure as in Example 1 except that the above was changed. The obtained multilayer sheet was evaluated for transparency, moisture resistance, heat resistance, and the like. The results are shown in Table 1.

(Example 6)
In Example 5, the multilayer sheet was obtained by the same method and thickness structure as Example 1 except having changed (D) -1 into (D) -2 in the resin composition which comprises resin layer (II). . The obtained multilayer sheet was evaluated for transparency, moisture resistance, heat resistance, and the like. The results are shown in Table 1.

(Example 7)
In Example 1, (B) -1, (C) -1, (D) -1, and (E) -1 were mixed in a resin mass (49.9: 0) constituting the resin layer (II). A multilayer sheet was obtained by the same method and thickness structure as in Example 1 except that the ratio was changed to 1:20:30. The obtained multilayer sheet was evaluated for transparency, moisture resistance, heat resistance, and the like. The results are shown in Table 1.

(Example 8)
In Example 7, a multilayer sheet was obtained by the same method and thickness structure as Example 7 except that (B) -1 in the resin composition constituting the resin layer (II) was changed to (B) -3. It was. The obtained multilayer sheet was evaluated for transparency, moisture resistance, heat resistance, and the like. The results are shown in Table 1.

Example 9
In Example 7, a multilayer sheet was obtained by the same method and thickness structure as Example 7 except that (B) -1 in the resin composition constituting the resin layer (II) was changed to (B) -4. It was. The obtained multilayer sheet was evaluated for transparency, moisture resistance, heat resistance, and the like. The results are shown in Table 1.

(Comparative Example 1)
In Example 1, a multilayer sheet was obtained by the same method and thickness structure as Example 1 except that (B) -1 was used alone as the resin composition constituting the resin layer (II). The obtained multilayer sheet was evaluated for transparency, moisture resistance, heat resistance, and the like. The results are shown in Table 1.

(Comparative Example 2)
In Example 1, (B) -1 in the resin composition constituting the resin layer (II) was manufactured by Prime Polymer Co., Ltd., trade name: Hi-Zex 3600F (high density polyethylene, ethylene = 100% by mass (100 mol) %), Density: 0.958 g / cm ³ , crystal melting peak temperature: 134 ° C., crystal melting heat amount: 195 J / g, crystallization peak temperature: 116 ° C., Mw / Mn: 4.72, and storage elastic modulus at 20 ° C. (E ′): 1581 MPa, MFR (temperature: 190 ° C., load: 21.18 N): 1 g / 10 min, hereinafter abbreviated as (P) -1) A multilayer sheet was obtained. The obtained multilayer sheet was evaluated for transparency, moisture resistance, heat resistance, and the like. The results are shown in Table 1.

(Comparative Example 3)
In Example 1, the resin composition constituting the resin layer (I) is the same resin composition as the resin layer (II), and a single-layer sheet having a total thickness of 0.3 mm substantially consisting of only the resin layer (II) Obtained. The obtained multilayer sheet was evaluated for transparency, moisture resistance, heat resistance, and the like. The results are shown in Table 1.

From Table 1, it can confirm that the multilayer body for solar cells of this invention satisfy | fills evaluation criteria for all the items evaluated, such as transparency, moisture resistance, and heat resistance (Examples 1-9). Moreover, when the olefin-compatible resin (D) is further added to the essential components of the ethylene resin (B) and the crystal nucleating agent (C) of the resin layer (II), the transparency and moisture resistance are further improved. (Example 5). Further, when the olefin-compatible resin (D) and the cyclic olefin resin (E) are further contained in the essential components of the ethylene resin (B) and the crystal nucleating agent (C) of the resin layer (II), It can confirm that all the evaluated items are excellent on a high standard (Examples 7-9).
On the other hand, when the crystal nucleating agent (C) is not included (Comparative Example 1) or when the heat of crystal melting of the ethylene resin (B) used for the resin layer (II) exceeds the provisions of the present invention (Comparative Example 2). In the case where the resin layer (I) constituting at least one of the outermost layers is not provided (Comparative Example 3), it can be confirmed that the sealing property and transparency are inferior.

(Example 10)
Using a vacuum laminator manufactured by NPC Corporation, product name “LM30 × 30”, hot plate temperature: 150 ° C., processing time: 20 minutes (breakdown, vacuuming: 5 minutes, press: 5 minutes , Pressure retention: 10 minutes), pressure bonding speed: under the conditions of rapid, in order from the hot plate side, white plate glass (made by Asahi Glass Co., Ltd., trade name: Solite) with a thickness of 3 mm as the upper protective material, the total obtained in the examples A multilayer sheet (sealing material) having a thickness of 0.3 mm, a solar cell element (cell) having a thickness of 0.4 mm (manufactured by Photowatt Co., Ltd., trade name: 101 × 101 MM), and the total thickness obtained in the examples is 0.00. A solar cell module (size) by vacuum pressing 5 layers of a 3 mm multilayer sheet (sealing material) and a weather-resistant PET film (product name: Lumirror X10S, manufactured by Toray Industries, Inc.) having a thickness of 0.125 mm as a lower protective material : 150mm x 150mm) . The obtained solar cell modules were excellent in transparency and appearance.

DESCRIPTION OF SYMBOLS 10 ... Transparent substrate 12A, 12B ... Sealing resin layer 14A, 14B ... Solar cell element 16 ... Back sheet 18 ... Junction box 20 ... Wiring

Claims (9)

The crystal melting peak temperature measured at a heating rate of 10 ° C./min in the differential scanning calorimetry is 100 to 100, having the resin layer (I) containing the silane-modified ethylene resin (A) as at least one of the outermost layers. Resin layer (II) containing ethylene resin (B) having a crystal melting heat of 120 to 190 J / g and at least one crystal nucleating agent (C) selected from fatty acid amides and fatty acid metal salts at 145 ° C. A multilayer body for solar cells , wherein the resin layer (I) is a resin layer mainly composed of a silane-modified ethylene resin (A), and a silane-modified ethylene resin (A) and a polyethylene-based material. A resin layer selected from a resin layer mainly composed of a mixture with the resin (F), wherein the content of the ethylene resin (B) in the resin layer (II) is 30 to 99.9% by mass, the crystal Nucleating agent C) is 0.01 to 3.0 wt% content of the resin layer (II) thickness ratio of 20% or more to the total thickness of the multilayer body for a solar cell is 60% or less. The resin layer (II) further contains at least one olefin-compatible resin (D) selected from the group consisting of petroleum resins, terpene resins, coumarone-indene resins, rosin resins, and hydrogenated derivatives thereof. The multilayer body for solar cells according to claim 1, wherein: The olefin-compatible resin (D) has a softening temperature Ts (D) of 80 ° C. or higher [the crystallization peak temperature Tc measured at a cooling rate of 10 ° C./min in the differential scanning calorimetry of the ethylene resin (B). (B) + 5 ° C.] or lower. The solar cell multilayer body according to claim 2 , wherein: The said resin layer (II) further contains cyclic olefin resin (E), The multilayer body for solar cells of any one of Claims 1-3 characterized by the above-mentioned. The multilayer body for solar cells according to any one of claims 1 to 4 , wherein at least one additive selected from an antioxidant, an ultraviolet absorber, and a weathering stabilizer is added. The total thickness of 0.3 mm, temperature 40 ° C., any one of claim 1 to 5, measured water vapor permeability at a relative humidity of 90% and wherein the at 3.0g / ^(m 2 · 24 hours) or less The multilayer body for solar cells described in 1. When measured at a total thickness of 0.3 mm, the water vapor permeability measured at a vibration frequency of 10 Hz, a storage elastic modulus (E ′) at a temperature of 20 ° C. of 300 to 700 MPa, a temperature of 40 ° C., and a relative humidity of 90% in dynamic viscoelasticity measurement. Is 3.0 g / (m ² · 24 hours) or less, and the total light transmittance is 85% or more, The multilayer body for solar cell according to any one of claims 1 to 6 . Multilayer body for a solar cell of any one of claim 1 to 7, characterized in that a solar cell sealing material to protect adhered to the solar cell element. The solar cell module produced using the multilayer body for solar cells of any one of Claims 1-8 , an upper protection material, a photovoltaic cell, and a lower protection material.

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