JP2014212268A - Laminate for solar cell and solar cell module manufactured using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminate for a solar cell module, which is excellent in interlayer adhesion between a protective resin layer and a sealing material layer, durability, and moisture resistance, and to provide a solar cell module manufactured using the same.SOLUTION: The laminate for a solar cell includes a protective resin layer and a sealing material layer arranged in contact with the protective resin layer. The protective resin layer satisfies the following condition (1), the sealing material layer satisfies the following condition (2), and the maximum delamination strength between the protective resin layer and the sealing material layer is 40 N/10 mm width or more. (1) The water vapor permeability per 100 μm thickness is 10 g/m/24 h or more. (2) The sealing material layer comprises an olefinic resin composition containing a compound having an alkoxysilane group.

Description

  The present invention relates to a laminate for a solar cell module excellent in interlayer adhesion, durability, and moisture resistance between a protective resin layer and a sealing material layer, and a solar cell module produced using the laminate.

  In recent years, photovoltaic power generation has attracted much attention as an energy source that is clean and useful for preventing global warming, and is already spreading. As a representative example of the solar power generation, a solar cell using a semiconductor such as single crystal silicon, polycrystalline silicon, amorphous silicon, and the like can be given. A solar cell is a practical application of the principle that current can be taken out when sunlight hits a semiconductor. One of the recent attention is a relatively large solar cell. These solar cells are places where the sun hits, such as unused land such as deserts and wasteland, and roofs of houses or large buildings, and are exposed to the natural environment outdoors. . When moisture reaches the semiconductor cell which is the heart of the solar battery, its performance is remarkably lowered. Therefore, the solar battery is required to have a package that can withstand a natural environment with severe strength and water resistance for a long period of time.

  From this point of view, the package is mainly used in a form in which a solar cell element is sealed using a transparent and strong glass substrate. However, in recent years, a solar cell module using a lightweight member that replaces a glass substrate is required from the viewpoint of workability.

  On the other hand, Patent Document 1 proposes a solar cell cover material in which a transparent high moisture-proof film and a high light-resistant film excellent in ultraviolet resistance are laminated and integrated, and a solar cell using this solar cell cover material. ing.

  Patent Document 2 proposes a flexible solar cell sheet in which a sealing material layer having adhesion to a metal is laminated on at least one surface of a transparent substrate without containing a crosslinking agent component. .

  In Patent Document 3, at least two layers of a transparent organic polymer resin layer provided on the light incident side surface of the photovoltaic element and a transparent surface protective film located on the outermost surface in contact therewith are provided. A covering material including the solar cell module covered with the covering material has been proposed. Further, it is disclosed that the adhesion between the surface protective film and the organic polymer resin layer is improved by forming irregularities on the surface of the covering material (see Patent Document 3, Claims 1 and 0014).

  Patent Document 4 discloses a solar cell cover film formed by laminating a weather resistant layer and a sealing material layer.

JP 2000-174296 A JP 2012-195491 A JP-A-8-139347 JP 2012-54365 A

  However, in the technique described in Patent Document 1, since a layer having moisture resistance, translucency, weather resistance, and UV resistance is laminated on the cover material, it is necessary to produce a plurality of functional films. An additional process such as a bonding process of these films is required.

  In Patent Document 2, there is a description about the adhesiveness between the cell and the sealing material layer, but there is no description regarding the adhesiveness between the transparent base material and the sealing material layer. For the bonding, an additional step of applying an adhesive is required.

  In Patent Document 3, irregularities are formed on the surface protective film of the covering material, and the adhesion can be improved to some extent by surface treatment by corona treatment, but a technique for controlling irregularities in the surface protective film is required in the production process.

  Patent Document 4 focuses on a solar cell cover film that is effective in reducing weight, impact resistance, and durability, and includes a weathering layer and a sealing material layer that constitute the solar cell cover film. Interlayer adhesion may be insufficient.

  An object of the present invention is to perform interlayer adhesion between a protective resin layer and a sealing material layer without performing an adhesion process for forming a functional layer in the light-receiving surface side protective material layer described above or a process such as unevenness control. It is providing the laminated body for solar cell modules excellent also in the property, durability, and moisture resistance, and a solar cell module produced using the same.

  As a result of intensive studies, the inventors have used the specified protective resin layer and the sealing material layer to achieve interlayer adhesion, durability, and moisture resistance between the protective resin layer and the sealing material layer. In addition, the inventors have found that an excellent solar cell laminate can be obtained, and have completed the present invention.

That is, the present invention relates to the following [1] to [9].
[1] A solar cell laminate having a protective resin layer and a sealing material layer disposed in contact with the protective resin layer, the protective resin layer satisfying the following condition (1), and the sealing A laminate for a solar cell, wherein the material layer satisfies the following condition (2), and the maximum delamination strength between the protective resin layer and the sealing material layer is 40 N / 10 mm or more.
(1) Water vapor permeability per 100 μm thickness is 10 g / m ² / 24h or more (2) Consists of an olefin-based resin composition containing a compound having an alkoxysilane group [2] Sealing material layer of the protective resin layer The laminate for a solar cell according to [1] above, wherein the wetting index of the surface in contact with is 50 mN / m or more.
[3] The solar cell laminate according to [1] or [2], wherein a main component of the resin composition constituting the protective resin layer is a polycarbonate resin or a polyester resin.
[4] The laminate for a solar cell according to any one of [1] to [3], wherein the protective resin layer has a dielectric constant of 2.7 or more at 23 ° C. and 1 MHz.
[5] The laminate for a solar cell according to any one of [1] to [4], wherein the olefin-based resin composition satisfies the following conditions (i) and (ii).
(I) A crystal melting peak temperature (Tm) of 100 ° C. or less measured at a heating rate of 10 ° C./min in differential scanning calorimetry, and a crystal melting heat of 100 ° C. or less of 10 J / g or more and 100 J / g (Ii) a crystal melting peak temperature (Tm) of 100 ° C. or higher measured at a heating rate of 10 ° C./min in differential scanning calorimetry, and a crystal melting heat of 100 ° C. or higher of 0.1 J / g or higher 70 J / g or less [6] in any one of [1] to [5] for the water vapor permeability per thickness 100μm of the sealing material layer is equal to or less than ^30g / m 2 / 24h The laminated body for solar cells as described.
[7] The solar cell laminate according to any one of [1] to [6], wherein the total light transmittance at a thickness of 450 μm of the sealing material layer is 85% or more.
[8] The solar cell laminate according to any one of [1] to [7], wherein the sealing material layer has a multilayer structure.
[9] A solar cell module having the solar cell laminate according to any one of [1] to [8].

  According to the present invention, the protective resin layer and the encapsulant are not required to be multi-layered in the protective resin layer, and the adhesion process between the protective resin layer and the encapsulant layer and the steps of unevenness control are not performed. The laminated body for solar cells excellent in the interlayer adhesiveness with a layer, durability, and moisture resistance can be provided.

It is a figure which shows the calculation method of crystal melting calorie | heat amount (DELTA) Hm (> 100 degreeC) of 100 degreeC or more. It is a figure which shows the sample for creep measurement at the time of evaluating heat resistance.

  Hereinafter, the laminated body for solar cells as an embodiment of the present invention and a solar cell module produced using the same will be described. However, the scope of the present invention is not limited to the embodiments described below.

  In the present specification, the term “main component” is intended to allow other components to be included within a range that does not interfere with the action / effect of the resin constituting each member of the laminate for solar cell of the present invention. is there. Further, this term does not limit the specific content, but it is 50% by mass or more, preferably 65% by mass or more, more preferably 80% by mass or more of the total components of the resin composition. It is a component occupying a range of mass% or less.

The laminate for solar cell of the present invention has a protective resin layer and a sealing material layer disposed in contact with the protective resin layer, and the protective resin layer satisfies the following condition (1): The sealing material layer satisfies the following condition (2), and the maximum delamination strength between the protective resin layer and the sealing material layer is 40 N / 10 mm width or more.
(1) Water vapor transmission rate per 100 μm thickness is 10 g / m ² / 24h or more (2) Consists of an olefin-based resin composition containing a compound having an alkoxysilane group

The present invention will be described in detail below.
<Protective resin layer>
The protective resin layer in the present invention is characterized by having a certain amount of water vapor permeability. Specifically, the water vapor permeability per thickness 100μm is ^10g / m 2 / 24h or more.

(Condition (1): Water vapor transmission rate)
Water vapor permeability of the protective resin layer used in the present invention (JIS K7105: temperature 40 ° C., humidity 90 RH, thickness 100 [mu] m) is ^10g / m 2 / 24h or more. Preferably, at ^15g / m 2 / 24h or more. Given the moisture resistance of the solar cell laminate, the upper limit is usually, 200g ^/ m 2 ^/ 24h approximately. If the water vapor transmission rate is within the above range, interaction such as hydrogen bond or covalent bond between the polar group such as silanol group of the compound having an alkoxysilane group contained in the sealing material layer described later and the surface of the protective resin layer Can be positively promoted, the interlaminar adhesion between the protective resin layer and the sealing material layer can be improved, and can be maintained or gradually increased over time by maintaining and advancing the interaction.
Moreover, if the water vapor transmission rate is in the above range, the modification effect in the surface treatment is great, and it is possible to improve the wetting index described later while suppressing the deterioration and deterioration of the protective resin layer during the surface treatment.

Moreover, it is more preferable that the protective resin layer of the present invention satisfies the following physical properties.
(Wetting index)
The protective resin layer used in the present invention preferably has a wetting index of 50 mN / m or more on the surface in contact with the sealing material layer. By setting the wetting index to 50 mN / m or more, it is advantageous for improving the adhesive force between the protective resin layer and the sealing material layer. If the wetting index is too small, the interlayer adhesion between the protective resin layer and the encapsulant layer becomes insufficient, and due to factors such as expansion and contraction due to external impact and temperature environment when used in solar cell modules There is a risk of peeling at the interface between the protective resin layer and the sealing material layer.
The wetness index is more preferably 60 mN / m or more, and still more preferably 65 mN / m or more, from the viewpoint of improving interlayer adhesion between the protective resin layer and the sealing material layer. Moreover, although it does not restrict | limit in particular about an upper limit, In order to improve a wetting index | exponent, the surface treatment method mentioned later is normally used. At this time, it is necessary to irradiate the protective resin layer with high energy during the treatment, and the upper limit of the wetting index is preferably about 75 mN / m from the viewpoint of preventing the material from being decomposed or deteriorated.
The “wetting index” is a wetting index of the surface of the protective resin layer before the protective resin layer and the sealing material layer are laminated. For example, after the surface treatment, the protective resin layer and the sealing material layer are laminated. This is the wetting index before the process.
When the wetting index in the protective resin layer is 50 mN / m or more, the surface treatment may be performed without performing the surface treatment, or the surface treatment may be performed for the purpose of further improving the adhesion.
Further, the wetting index of the surface of the protective resin layer opposite to the surface in contact with the sealing material layer is not particularly limited because it corresponds to the purpose and application. For example, in the case of an application requiring water repellency, 40 mN / Less than m is preferable.
The wetting index can be measured by the method described in the examples described later.

  As the surface treatment method for improving the wetting index, for example, a surface modification treatment for modifying by applying energy, an organic treatment for forming an organic layer, or the like is typically used.

As the surface modification treatment, corona discharge treatment, plasma discharge treatment, UV treatment, flame treatment or the like is preferably used. In order to obtain the wetting index defined in the present invention, it is necessary to adjust the amount of irradiation energy according to the light intensity during processing, the processing time, the irradiation distance, and the like. Also, even if the same amount of energy is given depending on the type of surface modification treatment, the material of the protective resin layer used and the surface condition, the same wetting index is not shown. There is a need to. For example, when performing surface modification treatment using a corona discharge treatment, the amount of irradiation energy is usually a 100W ^{/ m 2} ~4000W ^/ m 2 approximately, ^{preferably, 500W / m 2 ~3000W / m} 2 There, more ^{preferably 1000W / m 2 ~2000W / m 2} .

  As the organic treatment, plasma discharge organic treatment, primer coating treatment and the like are preferably used, and in the present invention, in consideration of wettability and adhesiveness, amine-based, acrylic-based, urethane having a highly polar or reactive functional group, etc. It is preferable to form an organic layer such as an epoxy type or an epoxy type.

(Dielectric constant)
The dielectric constant (temperature 23 ° C., frequency 1 MHz) of the protective resin layer used in the present invention is not particularly limited, but is preferably 2.7 or more, more preferably 2.9 or more. . Although an upper limit is not specifically limited, Usually, it is 5.0 or less, Preferably it is 4.5 or less. The dielectric constant is the polarization ability of the insulating material. If the above range is satisfied, the protective resin layer has a large proportion of polar groups and the surface modification effect is improved and the polarization state is maintained well after the modification. Interlayer adhesion with the sealing material layer can be improved or maintained.
In addition, a dielectric constant can be measured by the method as described in the Example mentioned later.

  The main component of the resin composition constituting the protective resin layer used in the present invention is not particularly limited as long as it satisfies the above condition (1). For example, polycarbonate resin, polyester resin, acrylic resin And publicly known resins such as polyethylene resins, polypropylene resins, cyclic polyolefin resins, polystyrene resins, polyvinyl chloride resins, polyphenylene ether resins, and polyphenylene sulfide resins.

In the protective resin layer used in the present invention, polycarbonate resins, polyester resins, polyphenylene ether resins, and the like are preferably used from the viewpoint of having weather resistance while having a certain amount of water vapor permeability. A resin or polyester resin is more preferably used.
Moreover, the resin composition which comprises the protective resin layer of this invention may further contain additives, such as a ultraviolet absorber mentioned later, a weather resistance stabilizer, a silane coupling agent, and antioxidant.

  The thickness of the protective resin layer of the present invention is not particularly limited, but is usually 500 μm or more, preferably 1000 μm or more in consideration of module rigidity and impact resistance in the case of the configuration of the solar cell module. . The upper limit is not particularly limited, but is usually about 5000 μm, preferably about 2000 μm. When considering the module configuration having flexible performance, the thickness of the protective resin layer is usually 20 μm or more, preferably 30 μm or more, and the upper limit is not particularly limited, but usually considering flexibility , About 1000 μm, and preferably about 500 μm.

<Encapsulant layer>
The sealing material layer used in the present invention is an olefin-based resin composition that is disposed in contact with the protective resin layer and contains a compound having an alkoxysilane group. By containing a compound having an alkoxysilane group in the sealing material layer, an interaction between the surface of the protective resin layer in contact with the sealing material layer and the sealing material layer is formed, and the protective resin layer and the sealing material layer And interlayer adhesion can be improved.
The encapsulant layer used in the present invention may have a single layer structure or a multilayer structure having a layer (adhesive layer) that contributes to adhesion containing a compound having an alkoxysilane group. However, when the sealing material layer has a multilayer structure having an adhesive layer, it is important that the adhesive layer is disposed in contact with the protective resin layer.

  Since the protective resin layer used in the present invention has a larger coefficient of linear expansion than a general protective layer such as glass, cell damage or internal wiring breakage due to expansion and contraction due to cooling after lamination or temperature change in the outdoor environment May occur. In order to suppress this phenomenon, the sealing material layer is required to select a highly flexible resin composition. In consideration of the water vapor transmission rate of the protective resin layer, it is important that the sealing material layer is a resin composition having a low water vapor transmission rate. From these viewpoints, it is important that the sealing material layer used in the laminate of the present invention is an olefin resin composition.

(Olefin resin)
Although it does not specifically limit as an olefin resin composition which comprises the sealing material layer of this invention, Specifically, the olefin shown by each of following (B-1)-(B-4) An olefin resin composition mainly composed of a polymer is preferably used. From the viewpoints of flexibility of the obtained sealing material layer, water vapor barrier properties, few fish eyes (gel), few corrosive substances (such as acetic acid) in the circuit and economy, (B-1) and (B -2) are preferable, and those shown in (B-1) are particularly preferably used because they are excellent in low temperature characteristics and weather resistance.

(B-1)
(B-1) is a copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms. Here, as the α-olefin copolymerized with ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 3-methyl- Examples include butene-1, 4-methyl-pentene-1.
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. Further, an ethylene-α-olefin random copolymer is preferably used from the viewpoint of transparency and flexibility. The α-olefin copolymerized with ethylene can be used alone or in combination of two or more.

  Further, the content of the α-olefin copolymerized with ethylene is not particularly limited, but the total amount in the copolymer (B-1) of ethylene and an α-olefin having 3 to 20 carbon atoms. The monomer based on an α-olefin having 3 to 20 carbon atoms is usually 2 mol% or more, preferably 40 mol% or less, more preferably 3 to 30 mol%, still more preferably 5 to 5 mol% based on the body unit. 25 mol%. Within such a range, the crystallinity is reduced by the copolymerization component, so that the transparency is improved and problems such as blocking of raw material pellets are less likely to occur. In addition, the kind and content of the monomer copolymerized with ethylene can be qualitatively quantitatively analyzed by a well-known method, for example, a nuclear magnetic resonance (NMR) measuring apparatus or other instrumental analyzers.

The copolymer (B-1) of ethylene and an α-olefin having 3 to 20 carbon atoms may contain a monomer unit based on a monomer other than the 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 preferably 20 mol when the total monomer units in the copolymer (B-1) of ethylene and an α-olefin having 3 to 20 carbon atoms is 100 mol%. % Or less, more preferably 15 mol% or less.
In addition, the three-dimensional structure, branching, branching degree distribution, molecular weight distribution and copolymerization type (random, block, etc.) of the copolymer (B-1) of ethylene and an α-olefin having 3 to 20 carbon atoms are particularly limited. For example, a copolymer having a long chain branch generally has good mechanical properties, and the melt tension (melt tension) at the time of molding a sheet increases, thereby improving the calendar moldability. There are advantages.

The melt flow rate (MFR) of the copolymer (B-1) of ethylene and an α-olefin having 3 to 20 carbon atoms used in the present invention is not particularly limited, but is usually MFR (JIS K7210). , Temperature: 190 ° C., load: 21.18 N) is about 0.5 to 100 g / 10 min, preferably 1 to 50 g / 10 min, more preferably 2 to 50 g / 10 min, still more preferably 3 to 30 g / 10 min. .
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 a relatively low value, specifically about 0.5 to 5 g / 10 min from the handling property when the sheet is peeled off from the molding roll. In the case of extruding using a mold, the MFR is preferably 1 to 50 g / 10 min, more preferably 2 to 50 g / 10 min, and further preferably 3 to 30 g / 10 min from the viewpoint of reducing the extrusion load and increasing the amount of extrusion. It is. 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).

  The production method of the copolymer (B-1) of ethylene and an α-olefin having 3 to 20 carbon atoms used in the present invention is not particularly limited, and is a known method using a known olefin polymerization catalyst. A polymerization method can be employed. For example, a slurry polymerization method, a solution polymerization method, a gas phase polymerization method, etc. using a multi-site catalyst typified by a Ziegler-Natta type catalyst, a single site catalyst typified by a metallocene catalyst or a post metallocene catalyst, etc. And a bulk polymerization method using a radical initiator. In the present invention, a polymerization method using a single-site catalyst capable of polymerizing a raw material having a low molecular weight component and a narrow molecular weight distribution is preferable from the viewpoints of easy granulation after pelletization and prevention of blocking of raw material pellets. is there.

  Specific examples of the copolymer (B-1) of ethylene and an α-olefin having 3 to 20 carbon atoms used in the present invention include trade names “Engage” and “Engage” manufactured by Dow Chemical Co., Ltd. “Affinity”, “Infuse”, trade name “Exact” manufactured by ExxonMobil Co., Ltd., trade names “TAFMER H”, “Tuffmer” manufactured by Mitsui Chemicals, Inc. Examples include A (TAFMER A), “TAFMER P”, LG Chemical Co., Ltd. trade name “LUCENE”, Nippon Polyethylene Co., Ltd. trade name “Kernel”, and the like. .

(B-2)
(B-2) is a copolymer of propylene and another monomer copolymerizable with the propylene, or a homopolymer of propylene. However, these copolymerization forms (random, block, etc.), branching, branching degree distribution and three-dimensional structure are not particularly limited, and can be a polymer having an isotactic, atactic, syndiotactic or mixed structure. .
Examples of other copolymerizable monomers include α-olefins having 4 to 12 carbon atoms such as ethylene, 1-butene, 1-hexene, 4-methyl-pentene-1, 1-octene, and divinylbenzene, Examples include dienes such as 4-cyclohexadiene, dicyclopentadiene, cyclooctadiene, and ethylidene norbornene.
In the present invention, ethylene or 1-butene is preferably used as the α-olefin copolymerized with propylene from the viewpoints of industrial availability, various characteristics, and economical efficiency. Moreover, a propylene-alpha-olefin random copolymer is used suitably from viewpoints, such as transparency and a softness | flexibility. The monomer copolymerized with propylene can be used alone or in combination of two or more.

  Further, the content of other monomers copolymerizable with propylene is not particularly limited, but other monomers copolymerizable with propylene with respect to all monomer units in (B-2). The monomer unit based on the monomer is usually 2 mol% or more, preferably 40 mol% or less, more preferably 3 to 30 mol%, and still more preferably 5 to 25 mol%. Within such a range, the crystallinity is reduced by the copolymerization component, so that the transparency is improved and problems such as blocking of raw material pellets are less likely to occur. In addition, the kind and content of the other monomer copolymerizable with propylene can be qualitatively and quantitatively analyzed by a known method, for example, a nuclear magnetic resonance (NMR) measuring device or other instrumental analyzer.

The melt flow rate (MFR) of (B-2) used in the present invention is not particularly limited, but usually MFR (JIS K7210, temperature: 230 ° C., load: 21.18 N) is 0.1. It is about 5 to 100 g / 10 min, preferably 2 to 50 g / 10 min, more preferably 3 to 30 g / 10 min.
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 performing extrusion molding using M, 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 amount. 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).

  The method for producing a copolymer of propylene and another monomer copolymerizable with the propylene or a homopolymer of propylene (B-2) used in the present invention is not particularly limited, and is publicly known. A known polymerization method using the above olefin polymerization catalyst can be employed. For example, a slurry polymerization method, a solution polymerization method, a gas phase polymerization method, etc. using a multi-site catalyst represented by a Ziegler-Natta type catalyst, a single site catalyst represented by a metallocene catalyst or a post metallocene catalyst, Examples thereof include a bulk polymerization method using a radical initiator. In the present invention, a polymerization method using a single-site catalyst capable of polymerizing a raw material having a low molecular weight component and a narrow molecular weight distribution is preferable from the viewpoints of easy granulation after pelletization and prevention of blocking of raw material pellets. is there.

  Specific examples of (B-2) used in the present invention include propylene-butene random copolymers, propylene-ethylene random copolymers, propylene-ethylene-butene-1 copolymers, and the like. As products, Mitsui Chemicals, Inc., trade names “TAFMER XM”, “NOTIO”, Sumitomo Chemical Co., Ltd., trade name “TAFFCELLEN”, manufactured by Prime Polymer Co., Ltd. Examples include the product name “PRIME TPO”, the product name “VERSIFY” manufactured by Dow Chemical Co., Ltd., and the product name “VistaMAX” manufactured by ExxonMobil Co., Ltd. it can.

(B-3)
(B-3) is a metal salt of a copolymer comprising an α-olefin such as ethylene or propylene and an unsaturated aliphatic carboxylic acid (preferred metals are Zn, Na, K, Li, Mg, etc.). .
Specific products include, for example, trade name “HIMILAN” manufactured by Mitsui Chemicals, Inc. and trade name “AMPLIFY IO” manufactured by Dow Chemical Co., Ltd.

(B-4)
(B-4) is an ethylene-based copolymer composed of ethylene and at least one monomer selected from vinyl acetate, unsaturated aliphatic carboxylic acid, and unsaturated aliphatic monocarboxylic acid alkyl ester.
Specific examples include an ethylene-acrylic acid copolymer, an ethylene-methacrylic acid copolymer, an ethylene-acrylic acid ester copolymer, and an ethylene-methacrylic acid ester copolymer. Here, examples of the ester component include alkyl esters having 1 to 8 carbon atoms such as methyl, ethyl, propyl, and butyl. In the present invention, it is not limited to the above two-component copolymer, but a three-component or more multi-component copolymer (for example, ethylene, an unsaturated aliphatic carboxylic acid, and an unsaturated fat) in which a third component is added. A ternary or higher copolymer suitably selected from group carboxylic acid esters). Here, the content of the monomer copolymerized with ethylene is usually 5 to 35% by mass with respect to all monomer units in the copolymer.

(Compound having alkoxysilane group)
The compound having an alkoxysilane group used in the present invention is an alkoxysilane compound having an organic functional group capable of reacting or compatible with an organic resin and a hydrolyzable group capable of binding to an inorganic material. A silicone compound or a silane-modified resin obtained by copolymerizing or grafting an alkoxysilane compound. Among them, silane coupling agents, silane-modified resins, and the like are preferably used from the viewpoint of industrial availability and economy.
The compounds having an alkoxysilane group may be used alone or in combination of two or more.

(Silane coupling agent)
Silane coupling agents include vinyl groups, acryloxy groups, methacryloxy groups such as unsaturated groups, amino groups, epoxy groups and other organic functional groups as well as hydrolyzable groups such as methoxy groups, ethoxy groups and other alkoxy groups. The compound which has can be mentioned. Specific examples of the silane coupling agent include N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane, N- (β-aminoethyl) -γ-aminopropylmethyldimethoxysilane, and γ-aminopropyltriethoxy. Examples include silane, vinyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, and the like. In the present invention, γ-glycidoxypropyltrimethoxysilane and γ-methacryloxypropyltrimethoxysilane are preferably used because of good adhesiveness and little discoloration such as yellowing. These silane coupling agents can be used alone or in combination of two or more.
The content of the silane coupling agent is based on 100 parts by mass of the olefin resin composition constituting the sealing material layer having a single layer structure or the resin composition constituting the adhesive layer of the sealing material layer having a multilayer structure. Preferably it is 0.5-50 mass parts, and it is more preferable that it is 1-30 mass parts. Within such a range, the function as the adhesive layer can be exhibited, and the properties such as flexibility, transparency, sealing property and heat resistance as the sealing material layer can be easily adjusted.
In the case of a sealing material layer having a multilayer structure, a silane coupling agent can also be contained in other layers other than the adhesive layer.

(Silane modified resin)
The silane-modified resin used in the present invention is not particularly limited, and examples thereof include resins obtained by polymerization of a resin such as polyethylene, polypropylene, silicone, and polyurethane and a silane coupling agent. From the viewpoint of industrial availability and economical efficiency, a silane-modified olefin resin is preferably used.
The method for producing the silane-modified olefin resin is not particularly limited. For example, the olefin-based resin shown in each of the above-described (B-1) to (B-4) (in particular, (B- 1) is preferable), and can be obtained by melt-mixing the above-described silane coupling agent and radical generator at high temperature and graft polymerization.

The content of the silane-modified resin is not particularly limited, but the olefin-based resin composition constituting the single layer structure sealing material layer, or the resin composition constituting the multilayer structure sealing material layer It is preferable that it is 1-50 mass parts in 100 mass parts, and it is more preferable that it is 5-30 mass parts. Within such a range, the function as the adhesive layer can be exhibited, and the properties such as flexibility, transparency, sealing property and heat resistance as the sealing material layer can be easily adjusted.
In the case of a sealing material layer having a multilayer structure, a silane-modified resin can be contained in other layers besides the adhesive layer.

(Olefin resin composition)
The olefin resin composition used in the present invention contains a compound having an alkoxysilane group and an olefin resin.
From the viewpoint of flexibility, transparency or heat resistance of the sealing material layer, the olefin resin composition preferably satisfies the following conditions (i) and (ii).
(I) A crystal melting peak temperature (Tm) of 100 ° C. or less measured at a heating rate of 10 ° C./min in differential scanning calorimetry, and a crystal melting heat of 100 ° C. or less of 10 J / g or more and 100 J / g (Ii) a crystal melting peak temperature (Tm) of 100 ° C. or higher measured at a heating rate of 10 ° C./min in differential scanning calorimetry, and a crystal melting heat of 100 ° C. or higher of 0.1 J / g or higher 70 J / g or less

The crystal melting peak temperature (Tm) of the above condition (i) is 100 ° C. or lower, preferably 80 ° C. or lower. Although it does not specifically limit as a minimum, Usually, it is about 40 degreeC. The heat of crystal melting at 100 ° C. or less under the above condition (i) is 10 J / g or more and 100 J / g or less, preferably 15 J / g or more and 80 J / g or less, more preferably 20 J / g or more and 70 J / g or less. g or less. If the crystal melting peak temperature (Tm) and the heat of crystal melting are within the above ranges, the flexibility and transparency of the encapsulant layer can be ensured, and when preparing pellets by mixing all the materials, This is preferable because blocking of pellets or the like is less likely to occur. In order to satisfy the above condition (i), the olefin resin of the above-mentioned (B-1) to (B-4), which usually has a crystal melting peak temperature (Tm) of 100 ° C. or less, in the olefin resin composition. (Hereinafter sometimes referred to as “resin having a Tm of 100 ° C. or lower”).
The crystal melting peak temperature (Tm) and the crystal melting calorie can be measured at a heating rate of 10 ° C./min according to JIS K7122 using a differential scanning calorimeter.

The olefin resin composition constituting the sealing material layer preferably satisfies the condition (ii). Therefore, the olefin-based resin composition used in the present invention not only contains a resin having a Tm of 100 ° C. or lower, but also has the crystal melting peak temperature (Tm) of 100 ° C. or higher. It is preferable to mix the olefin resin or silane-modified resin (hereinafter referred to as “resin having Tm of 100 ° C. or higher”) of B-4). In order to ensure excellent heat resistance, the olefin-based resin composition preferably has a crystal melting peak temperature (Tm) of 100 ° C. or higher, and more preferably has a crystal melting peak temperature (Tm) of 110 ° C. or higher. The upper limit of the crystal melting peak temperature (Tm) is not particularly limited, but is about 140 ° C. in consideration of the thermal deterioration of the solar cell element (cell) and the set temperature at the time of manufacturing the solar cell module.
In addition, the heat of crystal melting at 100 ° C. or higher under the above condition (ii) is 0.1 J / g or more and 70 J / g or less, preferably 0.1 J / g or more and 30 J / g or less, more preferably 1 J / g. g to 10 J / g.
Here, the crystal melting calorie ΔHm (≧ 100 ° C.) of 100 ° C. or higher is the portion of the melting peak area measured at a heating rate of 10 ° C./min in the differential scanning calorimetry (thermo shown in FIG. 1). It is calculated from the hatched part in the gram.

The mixing (containing) mass ratio (unit: mass%) of the resin having a Tm of 100 ° C. or lower and the resin having a Tm of 100 ° C. or higher is preferably 60:40 or higher and 98: 2 or lower, more preferably 70: 30 or more and 97: 3 or less. However, the total of the resin having a Tm of 100 ° C. or less and the resin having a Tm of 100 ° C. or more is 100 parts by mass. Here, it is preferable that the mixing (containing) mass ratio is in the above range because a sealing material layer excellent in balance such as heat resistance and transparency can be easily obtained.
The total of the resin having a Tm of 100 ° C. or less and the resin having a Tm of 100 ° C. or more to be contained in the olefin resin composition is not particularly limited, but is 50% by mass or more in the olefin resin composition. It is preferably 65% by mass or more, and more preferably 80% by mass or more.
In the case where the above-described resin having a Tm of 100 ° C. or less and a resin having a Tm of 100 ° C. or more are contained in the resin composition constituting the sealing material layer having a multilayer structure described later, a resin having a Tm of 100 ° C. or less If the total content of the Tm with the resin of 100 ° C. or higher and the mixing (containing) mass ratio are in the above range, the resin with the Tm of 100 ° C. or lower and the resin with the Tm of 100 ° C. or higher contained in the same layer. Although not necessarily required, both resins are preferably contained in the same layer. Further, it is more preferable that both resins are contained in the resin composition constituting each layer of the sealing material layer having a multilayer structure.

(Other resins)
The olefin-based resin composition is not limited to those described above for the purpose of further improving various physical properties (flexibility, heat resistance, transparency, adhesiveness, etc.), molding processability, economic efficiency, and the like without departing from the gist of the present invention. Resin can be included. Examples of resins other than those described above include modified polyolefin resins, tackifier resins, various elastomers (olefin-based, styrene-based, etc.) and the like.

(Modified polyolefin resin)
The type of the modified polyolefin resin is not particularly limited. For example, ethylene-vinyl acetate copolymer (EVA), ethylene-vinyl alcohol copolymer (EVOH), ethylene-methyl methacrylate copolymer (EMMA) ), Ethylene-ethyl acrylate copolymer (EEAA), ethylene-glycidyl methacrylate copolymer (EGMA), ionomer resin (ionic crosslinkable ethylene-methacrylic acid copolymer, ionic crosslinkable ethylene-acrylic acid copolymer) And at least one resin selected from the group consisting of maleic anhydride graft copolymers.

  The content of these modified polyolefin resins is not particularly limited, but is preferably 20% by mass or less in 100% by mass of the olefin resin composition constituting the sealing material layer, and is 10% by mass. The following is more preferable. When the content of the modified polyolefin resin is within the above range, various physical properties (flexibility, heat resistance, transparency, adhesiveness, etc.), molding processability, and the like of the sealing material layer can be easily adjusted.

(Tackifying resin)
Examples of tackifying resins include petroleum resins, terpene resins, coumarone-indene resins, rosin resins, and hydrogenated derivatives thereof. Specifically, examples of the petroleum resin include an alicyclic petroleum resin from cyclopentadiene or a dimer thereof and an aromatic petroleum resin from the C9 component, and examples of the terpene resin include β-pinene. Terpene resins and terpene-phenol resins, and as coumarone-indene resins, for example, coumarone-indene copolymers and coumarone-indene-styrene copolymers can be exemplified, and as rosin resins, for example, Examples thereof include rosin resins such as gum rosin and wood rosin, and esterified rosin resins modified with glycerin or pentaerythritol. In addition, the tackifying resin can be obtained mainly with various softening temperatures depending on the molecular weight, but from the viewpoint of compatibility when mixed with the above-mentioned polyolefin resin, bleed over time, color tone or thermal stability. It is particularly preferable to use a hydrogenated derivative of an alicyclic petroleum resin having a softening temperature of preferably 100 ° C. or higher and 150 ° C. or lower, more preferably 120 ° C. or higher and 140 ° C. or lower. Moreover, it is preferable that it is 20 mass% or less in 100 mass% of olefin resin compositions which comprise a sealing material layer, and, as for content of tackifying resin, it is more preferable that it is 10 mass% or less.

(Various elastomers)
Various elastomers are not particularly limited, and examples thereof include styrene-based elastomers, polyester-based elastomers, and polyamide-based elastomers. Of these, styrene-based elastomers are preferred from the viewpoint of transparency and hydrolysis resistance. Examples of the styrene-based elastomer include SEBS (Styrene-Ethylene-Butylene-Styrene), SEBC (Styrene-Ethylene-Butylene-Crystalline Block Copolymer), HSBR (hydrogenated styrene butadiene rubber), and the like. The styrene content is not particularly limited, but is preferably 20 mol% or less from the viewpoint of weather resistance. Further, the content of various elastomers is preferably 20% by mass or less, more preferably 10% by mass or less, in 100% by mass of the resin composition constituting the sealing material layer.

(Additive)
Various additives can be added to the olefin-based resin composition as necessary. Examples of the additive include an antioxidant, an ultraviolet absorber, a weather resistance stabilizer, a light diffusing agent, a nucleating agent, a pigment (for example, a white pigment), a flame retardant, and a discoloration preventing agent.

  Further, in this embodiment, it is not necessary to add a crosslinking agent or a crosslinking aid to the olefin resin composition, but it does not exclude the addition, for example, when high heat resistance is required. A cross-linking agent and / or a cross-linking aid can be added as long as the increase in resin pressure during extrusion molding and the generation of foreign matters such as gels and fish eyes can be suppressed.

  In the present embodiment, it is preferable that the encapsulant layer is not substantially crosslinked. Here, “substantially not crosslinked” means that the xylene solubles measured by ASTM 2765-95 is usually 70% by mass or more, preferably 85% by mass or more, more preferably 95% by mass or more.

(Antioxidant)
The antioxidant is not particularly limited, and various commercially available products can be applied. Examples of the antioxidant include various types such as phenol, sulfur, phosphite, such as monophenol, bisphenol, and high-molecular phenol.

  Examples of the monophenol antioxidant include 2,6-di-tert-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-tert-butyl-4-ethylphenol, and octadecyl-3- And (3,5-di-tert-butyl-4-hydroxyphenyl) propionate.

  Examples of the bisphenol antioxidant include 2,2′-methylene-bis- (4-methyl-6-tert-butylphenol) and 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. Can be mentioned.

  Examples of the polymeric phenolic antioxidant 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, tocopherol (vitamin E) and the like.

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

  Examples of the phosphite antioxidant include triphenyl phosphite, diphenylisodecyl phosphite, phenyl diisodecyl phosphite, 4,4′-butylidene-bis (3-methyl-6-tert-butylphenyl-di-tridecyl). ) Phosphite, cyclic neopentanetetraylbis (octadecyl phosphite), tris (mono and / or dinonylphenyl) phosphite, tris (2,4-di-tert-butylphenyl) phosphite, diisodecylpentaerythritol di Phosphite, 9,10-dihydro-9-oxa-10-phosphaphenalene-10-oxide, 10- (3,5-di-tert-butyl-4-hydroxybenzyl) -9,10-dihydro-9 -Oxa-10-phosphaphenance -10-oxide, 10-decyloxy-9,10-dihydro-9-oxa-10-phosphaphenanthrene, cyclic neopentanetetraylbis (2,4-di-tert-butylphenyl) phosphite, Examples thereof include cyclic neopentanetetraylbis (2,6-di-tert-butylphenyl) phosphite, 2,2-methylenebis (4,6-tert-butylphenyl) octyl phosphite.

  In the present embodiment, phenolic and phosphite antioxidants are preferably used from the viewpoint of the effect of the antioxidant, thermal stability, economy, etc., and the combination of both is used to oxidize the added amount. Since the effect as an inhibitor can be heightened, it is further preferable.

  Although the addition amount of antioxidant is not limited, It is preferable that it is 0.1 mass part or more normally 1 mass part or less with respect to 100 mass parts of olefin resin compositions which comprise a sealing material layer. The range is more preferably 0.2 parts by mass or more and 0.5 parts by mass or less.

(UV absorber)
As the ultraviolet absorber, various commercially available products can be applied, and various types such as benzophenone-based, benzotriazole-based, triazine-based, and salicylic acid ester-based materials can be exemplified.

  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, etc. Door can be.

  Examples of the benzotriazole ultraviolet absorber include hydroxyphenyl-substituted benzotriazole compounds such as 2- (2-hydroxy-5-methylphenyl) benzotriazole and 2- (2-hydroxy-5-tert-butyl). Phenyl) benzotriazole, 2- (2-hydroxy-3,5-dimethylphenyl) benzotriazole, 2- (2-hydroxy-5-tert-octylphenyl) -2H-benzotriazole, 2- (2-methyl-4) -Hydroxyphenyl) benzotriazole, 2- (2-hydroxy-3-methyl-5-tert-butylphenyl) benzotriazole, 2- (2-hydroxy-3,5-di-tert-amylphenyl) benzotriazole, 2 -(2-hydroxy-3,5-di-tert And butyl phenyl) benzotriazole.

  Examples of the triazine ultraviolet absorber include 2- [4,6-bis (2,4-dimethylphenyl) -1,3,5-triazin-2-yl] -5- (octyloxy) phenol, 2- And (4,6-diphenyl-1,3,5-triazin-2-yl) -5- (hexyloxy) phenol.

  Examples of salicylic acid esters include phenyl salicylate and p-octylphenyl salicylate.

  Although the addition amount of a ultraviolet absorber is not limited, Usually, it is 0.01 mass part or more and 2.0 mass parts or less with respect to 100 mass parts of olefin resin compositions which comprise a sealing material layer. It is more preferable that it is 0.05 parts by mass or more and 0.5 parts by mass or less.

(Weather resistance stabilizer)
A hindered amine light stabilizer is suitably used as a weather stabilizer that imparts weather resistance in addition to the above ultraviolet absorber. The hindered amine light stabilizer does not absorb ultraviolet rays like the ultraviolet absorber, but has a remarkable synergistic effect when used in combination with the ultraviolet absorber.

  Examples of the hindered amine light stabilizer 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-diter 4-hydroxybenzyl) -2-n-butyl malonic acid bis (1,2,2,6,6-pentamethyl-4-piperidyl) and the like.

  The addition amount of the hindered amine light stabilizer is not limited, but is usually 0.01 parts by mass or more and 0.5 parts by mass or less with respect to 100 parts by mass of the olefin resin composition constituting the sealing material layer. It is preferable that it is 0.05 mass part or more and 0.3 mass part or less.

  Said antioxidant, ultraviolet absorber and weathering stabilizer may be used alone or in combination of two or more.

(Encapsulant layer)
The encapsulant layer of the present invention (hereinafter sometimes abbreviated as encapsulant) is composed of the olefin resin composition described above.
The sealing material layer of the present invention more preferably satisfies the following physical properties.

(Heat-resistant)
The heat resistance of the sealing material of the present invention is influenced by various properties (MFR, molecular weight, etc.) of the resin contained in the olefin-based resin composition, and can be adjusted by appropriately selecting these. In general, since the solar cell module is heated to about 85 ° C. due to heat generated during power generation or radiant heat of sunlight, the olefin resin composition has a crystal melting peak temperature (Tm) of 100 ° C. or higher, and It is preferable that the heat of crystal melting at 100 ° C. or higher is 0.1 J / g or more and 70 J / g or less because heat resistance can be secured. The heat resistance was evaluated by creep measurement described later.

(Water vapor transmission rate (WVTR))
The WVTR per 100 μm thickness of the sealing material of the present invention is not particularly limited as long as the specified resin composition is used, but excellent moisture resistance and durability of the laminate for solar cells. to ensure, preferably not more than ^30g / m 2 / 24h, more preferably not more than ^20g / m 2 / 24h. The lower limit, but are not particularly limited, but is usually, ^1g / m 2 / 24h approximately.

(transparency)
The total light transmittance of the sealing material of the present invention can be used as a back side of the cell or 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. When applied, it may not be very important, but considering the photoelectric conversion efficiency of the solar cell, the total light transmittance at 450 μm is preferably 85% or more, more preferably 87% or more. 89% or more is more preferable. The total light transmittance can be measured by the method described in Examples described later.

(Normal temperature flexibility)
The flexibility at normal temperature of the sealing material of the present invention is not particularly limited. It can be appropriately adjusted in consideration of the shape and thickness of the solar cell to be applied, the installation location, and the like.
For example, the storage elastic modulus (E ′) at a vibration frequency of 10 Hz and a temperature of 20 ° C. in the dynamic viscoelasticity measurement of the sealing material is preferably 1 to 2000 MPa. In consideration of protection and flexibility of the solar cell element, the pressure is more preferably 1 to 200 MPa, and further preferably 5 to 100 MPa. In the case where the encapsulant has a multilayer configuration described later, the storage elastic modulus (E ′) refers to the storage elastic modulus of the entire multilayer configuration of the encapsulant. In addition, handling properties when the sealing material 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 (about 1.1 mm) is applied. In consideration of the possibility or a glass-less configuration is applicable), it is preferably 1 to 1000 MPa, and more preferably 5 to 200 MPa. The storage elastic modulus (E ′) is obtained by measuring a predetermined temperature range at a vibration frequency of 10 Hz using a viscoelasticity measuring device and obtaining a value at a temperature of 20 ° C.

(Method for producing sealing material layer)
Next, the manufacturing method of the sealing material layer of this invention (henceforth abbreviated as sealing material) is demonstrated.
The shape of the sealing material is not limited and may be liquid or sheet-like, but is preferably sheet-like from the viewpoint of handleability.

  Further, the encapsulant of the present invention has a single layer or a multi-layer structure, but in order to achieve the properties required for the encapsulant in a balanced manner, a multi-layer structure composed of a plurality of layers having different composition contents and composition ratios is preferable. . In the case of a multilayer structure, the layer structure is not particularly limited. For example, a two-layer structure composed of (I) layer and (II) layer, or (I) layer / (II) layer / (I) A two-type three-layer structure in which layers are stacked in order.

As a method for forming a sheet-like sealing material, a known method, for example, an extrusion casting method using a T-die, a calendar having a melt mixing facility such as a single screw extruder, a multi-screw extruder, a Banbury mixer, a kneader, etc. In the present invention, a co-extrusion method using a plurality of extruders is preferably used from the viewpoints of handleability, productivity, and the like. The molding temperature in the co-extrusion method using a T die is appropriately adjusted depending on the flow characteristics and film-forming properties of the resin composition to be used, but is generally 130 to 300 ° C, preferably 150 to 250 ° C.
The thickness of the sheet-like sealing material is not particularly limited, but is usually 0.03 mm or more, preferably 0.05 mm or more, more preferably 0.1 mm or more, and usually 1 mm or less, preferably 0. 0.7 mm or less, more preferably 0.5 mm or less.

Various additives such as silane coupling agents, antioxidants, UV absorbers, and weathering stabilizers may be dry blended with the resin in advance and then supplied to the hopper. It may be supplied after making, or a master batch in which only the additive is previously concentrated in the resin may be made and supplied. In addition, on the surface and / or the back surface of the sealing material obtained in the form of a sheet, if necessary, the sheet can be used as a scroll to prevent blocking between sheets, and in the laminating process of the solar cell element, air handling properties and air Embossing and various unevenness (cone, pyramid shape, hemispherical shape, etc.) processing may be performed for the purpose of improving ease of punching.
In addition, various surface treatments such as corona treatment, plasma treatment and primer treatment can be performed on the surface for the purpose of improving adhesion to various adherends. Here, as a standard of the surface treatment amount, the wetting index is preferably 40 mN / m or more, and more preferably 50 mN / m or more. The upper limit of the wetting index is generally about 70 mN / m.

<Laminated body for solar cell>
The laminated body for solar cells of this invention has the said sealing resin layer and the sealing material layer distribute | arranged in contact with a protective resin layer. In order to further improve the interlayer adhesion in a range that does not inhibit the interaction between the surface of the protective resin layer in contact with the sealing material layer and the compound having an alkoxysilane group contained in the sealing material layer, Another layer such as a discontinuous easy adhesion layer or an anchor layer can be provided between the layer and the sealing material layer.

(Manufacturing method of laminate for solar cell)
The laminated body for solar cells of this invention can be obtained by laminating | stacking the said protective resin layer and a sealing material layer. For example, you may laminate | stack the said protective resin layer and the said sealing material layer which were previously manufactured in the sheet form by well-known methods, such as thermal lamination. Further, the sealing material layer may be laminated while being melt-extruded on the protective resin layer manufactured in advance.

(Interlayer adhesion between protective resin layer and sealing material layer)
About the interlayer adhesiveness of the protective resin layer and the sealing material layer in the laminated body for solar cells of this invention, it evaluated by the delamination test as described in the Example mentioned later.
The maximum delamination strength between the protective resin layer and the sealing material layer of the laminate of the present invention is 40 N / 10 mm width or more. The maximum delamination strength is more preferably 50 N / 10 mm width or more. Here, the maximum delamination strength is the maximum value of delamination strength in a chart obtained by measuring the delamination test described later on the laminate immediately after the production of the present invention (hereinafter referred to as “initial maximum”). Sometimes referred to as “delamination strength”). The term “immediately after production” means that after the laminate of the present invention is produced, the laminate is placed in an environment at a temperature of 25 degrees and a humidity of 50% within 5 hours.
In the solar cell laminate of the present invention, it is expected that the interlayer adhesion is stabilized and improved by the reaction between water vapor that has passed through the protective resin layer and the compound having an alkoxysilane group contained in the sealing material. Can do. Interlaminar adhesion retention after placing the solar cell laminate of the present invention in an environment of 25 ° C. and 50% humidity for 120 hours (interlaminar adhesion retention after 120 hours = maximum delamination after 120 hours) Strength / initial maximum delamination strength × 100%) is preferably 70% or more, more preferably 80% or more, and even more preferably 100% or more.
The maximum delamination strength after 120 hours between the protective resin layer and the sealing material layer of the laminate of the present invention is preferably 40 N / 10 mm width or more, more preferably 50 N / 10 mm width or more, and 60 N More preferably, the width is not less than / 10 mm.
Further, the interlayer adhesiveness retention after placing the solar cell laminate of the present invention in an environment of 25 ° C. and 50% humidity for 300 hours (interlayer adhesiveness retention after 300 hours = maximum after 300 hours) (Delamination strength / initial maximum delamination strength × 100%) is preferably 70% or more, more preferably 80% or more, and even more preferably 110% or more.
The maximum delamination strength after 300 hours between the protective resin layer and the sealing material layer of the laminate of the present invention is preferably 40 N / 10 mm width or more, more preferably 50 N / 10 mm width or more, and 60 N More preferably, the width is not less than / 10 mm.

<Solar cell module>
Using the solar cell laminate of the present invention, for example, the upper part of the solar cell element is fixed with the solar cell laminate of the present invention, and the lower part of the solar cell element is sealed with a sealing material layer and a lower protective material (back sheet). A solar cell module can be produced by fixing. Further, the upper part of the solar cell element can be fixed with a transparent base material (front sheet) and a sealing material layer, and the lower part of the solar cell element can be fixed with the laminate for solar cell of the present invention. A solar cell module can also be manufactured using the laminated body for solar cells of the present invention for both the upper part and the lower part. Examples of such solar cell modules include various types.

  In the solar cell module of the present invention, the same applies when the encapsulant layer (the encapsulant layer includes the encapsulant layer constituting the laminate of the present invention) is used at two or more sites. A sealing material layer made of a resin composition may be used, or a sealing material layer made of a different resin composition may be used. The sealant layer must be transparent when used in a site that requires light transmission, but may not be transparent when used as a backsheet-side sealant layer.

  As a specific example, the solar cell laminate of the present invention (in this case, a sealing material layer is disposed on the solar cell element side), solar cell element, and sealing material in order from the sunlight receiving side. A layer and a lower protective material (back sheet) are laminated, and a junction box (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. . The solar cell elements are connected by wiring in order to conduct the generated current to the outside. The wiring is taken out to the outside through a through hole provided in the sealing material layer and the back sheet, and connected to the junction box.

  Examples of the lower protective material include single-layer or multi-layer sheets such as metals, inorganic materials, and various thermoplastic resin films. For example, metals such as tin, aluminum, and stainless steel, inorganic materials such as glass, polyester, and inorganic vapor-deposited polyester And a single-layer or multilayer protective material made of a thermoplastic resin such as fluorine-containing resin or polyolefin.

  As another specific example, the upper protective material, the sealing material layer, the solar cell element, and the solar cell laminate of the present invention (in this case, sealed on the back side of the solar cell element) Further, a junction box (a terminal box for connecting wiring for extracting electricity generated from the solar cell element to the outside) is bonded to the lower surface of the solar cell laminate of the present invention. The solar cell elements are connected by wiring in order to conduct the generated current to the outside. The wiring is taken out through a through-hole provided in the solar cell laminate of the present invention and connected to a junction box.

The upper protective material is a single-layer or multi-layer sheet such as an inorganic material or various thermoplastic resin films. For example, a single-layer or multi-layer sheet made of a thermoplastic resin such as polyester, inorganic vapor-deposited polyester, fluorine-containing resin, or polyolefin. A protective material can be mentioned.
Examples of solar cell elements include single crystal silicon type, polycrystalline silicon type, amorphous silicon type, III-V group and II-VI group compound semiconductor types such as gallium-arsenic, copper-indium-selenium, cadmium-tellurium, Examples include a dye sensitizing type and an organic thin film type.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited by these examples and comparative examples. In addition, the measurement and evaluation of various physical properties of the protective resin layer, the sealing material layer, or the solar cell laminate in this example were performed as follows.

(Wetting index)
The wetting index of the protective resin layer and the sealing material layer in the present invention is obtained by impregnating a cotton swab with a wetting reagent based on JIS K6768 using a wet tension test mixture (30 mN / m to 70 mN / m). It was applied in the form of a line on the surface of the layer or the sealing material layer and obtained from the wet state of the reagent after 2 seconds.

(Dielectric constant)
In the present invention, a dielectric constant is measured using a precision LCR meter (4284A manufactured by Yokogawa HP) based on JIS K6911, with a sample size of 100 mm × 100 mm, an electrode diameter (φ) of 4.5 cm, and a vacuum dielectric constant of 8.854 × 10 ^12. Evaluation was performed under the conditions of 20 ° C. and humidity 65%.

(Total light transmittance)
Each sealing material layer having a thickness of 0.45 mm was stacked between two pieces of white plate glass having a thickness of 2 mm (size: length 75 mm, width 25 mm), and then laminated and pressed using a vacuum press machine at 150 ° C. for 15 minutes. A sample was prepared, and the total light transmittance was measured according to JIS K7105.

(Water vapor transmission rate measurement)
In the present invention, the water vapor transmission rate is measured using a water vapor transmission rate measuring device (manufactured by MOCON, product name: PERMATRAN-W), using a protective resin layer or a sealing material layer as a sample, at a temperature of 40 ° C. and RH of 90%. The water vapor transmission rate at 24 hours was measured and the water vapor transmission rate was determined. Moreover, the water vapor permeability of the sealing material layer was evaluated according to the following criteria.
○: sealing material layer of the water vapor transmission rate of ^30g / m 2 / 24h less × in the thickness 100μm terms: water vapor permeability of the sealing material layer in a thickness 100μm terms is ^30g / m 2 / 24h or more

(Delamination test)
The delamination strength in the present invention was measured using a universal tensile tester (manufactured by Intesco, model: 200X). When producing a laminate having a release film (Lumirror) described in each example as a margin for peeling, it is inserted into the interface portion between the protective resin layer and the sealing material layer, and the back has an easy-adhesion layer as the backing material A sample was prepared by laminating with a configuration of protective resin layer / sealing material layer / back sheet using a sheet (300 μm manufactured by COVEME). After that, the sample was cut into a 10 mm width strip, left for a predetermined time (immediately after sample preparation, 120 hours, 300 hours), and then delaminated using a universal tensile tester (180 degree peel, test speed 50 mm / min). ) The maximum value (maximum delamination strength) in the chart was read from the measurement result of delamination strength, and the interlayer adhesion and the retention of interlayer adhesion were evaluated according to the following criteria.
<Evaluation criteria for interlayer adhesion>
A: Maximum delamination strength is 50 N / 10 mm width or more. ○: Maximum delamination strength is 40 N / 10 mm width or more and less than 50 N / 10 mm width. X: Maximum delamination strength is less than 40 N / 10 mm width. Evaluation criteria>
(A) Interlayer adhesion retention after 120 hours A: Interlayer adhesion retention after 120 hours is 100% or more. O: Interlayer adhesion retention after 120 hours is 80% or more and less than 100%. Retention rate of interlayer adhesion after 120 hours is 70% or more and less than 80% ×: Retention rate of interlayer adhesion after 120 hours is less than 70% (b) Retention rate of interlayer adhesion after 300 hours A: 300 hours Retention rate of interlayer adhesion after 110% or more ○: Retention rate of interlayer adhesion after 300 hours is 80% or more and less than 110% Δ: Retention rate of interlayer adhesion after 300 hours is 70% or more and less than 80% ×: Interlayer adhesion retention after 300 hours is less than 70%

(Creep measurement)
Samples for creep measurement in the present invention are shown in FIGS. 2 (a) and 2 (b). In the center of the upper end side of the plate glass 101 (50 mm × 150 mm × 2 mm), a sealing material layer 102 (cut out size: 25 mm × 75 mm) and a slide glass 103 (25 mm × 75 mm × 1 mm) are used. After laminating at the order of layer 102 / slide glass 103, laminating at 150 ° C., two samples for creep measurement were prepared, and then the two samples were subjected to the following measurement conditions (A) and (B), A stainless steel plate 104 (size: length 75 mm, width 25 mm) with a predetermined weight was bonded to the slide glass side, set at a predetermined angle, and left in a constant temperature bath at a predetermined temperature for 24 hours. Thereafter, the amount of deviation of the slide glass 103 in each sample was determined (FIG. 2 (c)).
Then, the percentage of the amount of deviation of the obtained slide glass 103 (the amount of deviation of the slide glass 103/75 mm (maximum amount of deviation) × 100%) was determined. The heat resistance of the sealing material layer was evaluated on the basis of ii) heat resistance.
(I) Measurement conditions Condition A: Creep at 100 ° C, stainless steel plate 104 mass 28g, angle 60 ° Condition B: Creep at 120 ° C, stainless steel plate 104 mass 56g, angle 90 ° (ii) Heat resistance standard ○: Condition A and The percentage of deviation of the slide glass 103 under condition B is less than 10%. Δ: The percentage of deviation of the slide glass 103 under condition A alone is less than 10%.
X: The percentage of the deviation amount of the slide glass 103 under the condition A is 10% or more.

(MFR measurement)
Melt mass flow rate (MFR) measurement in the present invention was performed according to JIS K7210 (temperature: 190 ° C., load: 21.18 N).

(Crystal melting peak temperature (Tm))
Using a differential scanning calorimeter manufactured by PerkinElmer, Inc., under the trade name “Pyris1 DSC”, according to JIS K7121, about 10 mg of the sample was heated from −40 ° C. to 200 ° C. at a heating rate of 10 ° C./min. After holding at 200 ° C. for 5 minutes, the temperature was decreased to −40 ° C. at a cooling rate of 10 ° C./min, and again from the thermogram obtained when the temperature was increased to 200 ° C. at a heating rate of 10 ° C./min ( Tm) was determined.

(Crystal melting heat (ΔHm))
Using a differential scanning calorimeter manufactured by PerkinElmer Co., Ltd., trade name “Pyris1 DSC”, according to JIS K7122, about 10 mg of the sample was heated from −40 ° C. to 200 ° C. at a heating rate of 10 ° C./min. After holding at 200 ° C. for 5 minutes, the temperature was lowered to −40 ° C. at a cooling rate of 10 ° C./min, and again from the thermogram obtained when the temperature was raised to 200 ° C. at a heating rate of 10 ° C./min (ΔHm ) And 100 ° C. or higher crystal melting heat (ΔHm (≧ 100 ° C.)) (J / g).

The method for producing the sealing material layer in the present invention will be described below.

<Encapsulant layer 1>
Ethylene-octene random copolymer (manufactured by Mitsui Chemicals, Inc., trade name: TAFMER H5030S, MFR: 5, Tm: 59 ° C., ΔHm: 56 J / g, ΔHm (≧ 100 ° C.): 0 J / g) (hereinafter, 80 parts by mass (abbreviated as “PE-1”), a modified silane copolymer (manufactured by Mitsubishi Chemical Co., Ltd., trade name: Linkron SL800N, MFR: 1, Tm: 54 ° C. and 116 ° C., ΔHm: 45 J / G, ΔHm (≧ 100 ° C.): 5 J / g) (hereinafter abbreviated as (SiR-1)) A resin composition mixed at a ratio of 20 parts by mass (hereinafter abbreviated as resin composition (C-1)). The mixture was melt-kneaded at a preset temperature of 200 ° C. using an extruder equipped with a T die, and rapidly cooled with a 20 ° C. cast roll to obtain a sealing material having a thickness of 450 μm. Moreover, it evaluated as above-mentioned using the obtained sealing material. The results are shown in Table 1.

<Encapsulant layer 2>
The sealing material layer 2 has a two-layer / three-layer structure in which (I) layer / (II) layer / (I) layer are laminated in this order. As the (I) layer, the resin composition (C-1), and as the (II) layer, 95 parts by mass of the (PE-1) and an ethylene-octene block copolymer (manufactured by Dow Chemical Co., Ltd.) , Trade name: Infuse D9100.05, MFR: 1, Tm: 119 ° C., ΔHm: 45 J / g, ΔHm (≧ 100 ° C.): 41 J / g (hereinafter abbreviated as (PE-2)) 5 mass The resin composition (hereinafter abbreviated as “resin composition C-2”) mixed at a ratio of 1 part is used, and the layers are laminated in the order of (I) layer / (II) layer / (I) layer, After co-extrusion molding at a resin temperature of 180 ° C. to 200 ° C. by a T-die method using a co-directional twin-screw extruder, the film was quenched with a cast embossing roll at 20 ° C., and a sealing material ((I ) Layer / (II) layer / (I) layer = 45 μm / 360 μm / 45 μm) It was. Moreover, it evaluated as above-mentioned using the obtained sealing material. The results are shown in Table 1.

<Encapsulant layer 3>
In the sealing material layer 2, as the (I) layer, an ethylene-octene random copolymer (manufactured by Prime Polymer Co., Ltd., trade name: Evolu P 9018, MFR: 1, Tm: 88 ° C., ΔHm: 65 J / g, ΔHm (≧ 100 ° C.): 2 J / g) (hereinafter abbreviated as (PE-3)), general-purpose LLDPE (manufactured by Co., Ltd., trade name: NEOZEX 0234N, MFR: 2, Tm: 118 C, ΔHm: 122 J / g, ΔHm (≧ 100 ° C.): 66 J / g) (hereinafter abbreviated as (PE-4)) and 20 parts by mass of (SiR-1). The sealing material layer except that the resin composition was changed to a resin composition mixed at a ratio of 80 parts by mass of (PE-3) and 20 parts by mass of (PE-4) as the (II) layer. A sealing material is prepared and evaluated in the same manner as in 2. The results are shown in Table 1.

<Preparation of sealing material layer 4>
In the sealing material layer 1, a sealing material was produced in the same manner as the sealing material layer 1 except that the resin composition (C-1) was changed to a resin composition consisting only of the (PE-1). And evaluated. The results are shown in Table 1.

  Examples and comparative examples in the present invention are described below.

<Example 1>
As a protective resin layer, a polycarbonate film (manufactured by Mitsubishi Gas Chemical Co., Ltd., trade name: Iupilon FE-2000S, thickness 100 [mu] m, the water vapor transmission rate: ^45g / m 2 / 24h, a dielectric constant of 3.0) was used, the sealing material The produced sealing material layer 1 was used as the layer. One side of the protective resin layer and the sealing material layer was subjected to corona treatment with an irradiation energy amount of 1000 W / m ² . Thereafter, the treated surfaces were laminated and laminated, and then a laminate was produced at a lamination temperature of 150 ° C. by vacuum heating for 5 minutes and pressurization for 5 minutes. Various evaluation results of the protective resin layer and the produced laminate are shown in Table 1.

<Example 2>
A laminate was produced in the same manner as in Example 1 except that the sealing material layer was changed to the sealing material layer 2. Various evaluation results of the protective resin layer and the produced laminate are shown in Table 1.

<Example 3>
In the corona treatment on one side of the protective resin layer, a laminate was produced in the same manner as in Example 1 except that the irradiation energy amount was changed to 2000 W / m ² . Various evaluation results of the protective resin layer and the produced laminate are shown in Table 1.

<Example 4>
Polyester film protective resin layer (Mitsubishi Plastics Co., Ltd., trade name: DIAFOIL, thickness 125 [mu] m, the water vapor transmission rate ^25g / m 2 / 24h, dielectric constant 2.9) except that a, in the same manner as in Example 1 A laminate was produced by the method. Various evaluation results of the protective resin layer and the produced laminate are shown in Table 1.

<Example 5>
A laminate was produced in the same manner as in Example 1 except that the sealing material layer was changed to the sealing material layer 3. Various evaluation results of the protective resin layer and the produced laminate are shown in Table 1.

<Comparative Example 1>
A laminate was produced in the same manner as in Example 1 except that the protective resin layer was not subjected to corona treatment. Various evaluation results of the protective resin layer and the produced laminate are shown in Table 1.

<Comparative example 2>
In corona treatment one side of the protective resin layer, was changed to corona treatment irradiation energy 500 W / m ^2, to prepare a laminate in the same manner as in Example 1. Various evaluation results of the protective resin layer and the produced laminate are shown in Table 1.

<Comparative Example 3>
A laminate was produced in the same manner as in Example 1 except that the sealing material layer was changed to the sealing material layer 4. Various evaluation results of the protective resin layer and the produced laminate are shown in Table 1.

<Comparative example 4>
The sealing material layer EVA-based sealing material layer (Mitsuihigashi Cerro Co., Ltd., trade name: Solar EVA, after heat treatment 620 .mu.m, a water vapor transmission rate ^24g / m 2 / 24h), except that the, same manner as in Example 1 A laminate was prepared by the method described above. Various evaluation results of the protective resin layer and the produced laminate are shown in Table 1.

<Comparative Example 5>
The protective resin layer ETFE (manufactured by Asahi Glass Co., Ltd., trade name: Aflex ETFE, thickness: 25 [mu] m, the water vapor transmission rate ^28g / m 2 / 24h, dielectric constant 2.6) except that a, similarly to Example 1 A laminate was prepared by the method described above. Various evaluation results of the protective resin layer and the produced laminate are shown in Table 1.

  As is apparent from the results in Table 1, the solar cell laminate having the characteristics defined in the present invention is ensured by an excellent interlayer adhesion, retention of interlayer adhesion, and moisture resistance (sealing material layer having excellent water vapor barrier properties). ) And durability (secured by interlayer adhesiveness, retention of interlayer adhesiveness, and moisture resistance) (Examples 1 to 5). Moreover, in the structure which does not satisfy the requirements of this invention, it was confirmed that it is inferior to any one or more characteristics of interlayer adhesiveness, interlayer adhesiveness retention, or moisture resistance (Comparative Examples 1 to 5). Therefore, by using the laminate of the present invention, it is possible to realize a lightweight solar cell module using a transparent protective resin layer with little reduction in power generation efficiency and adhesion due to moisture absorption.

  According to the present invention, the protective resin layer and the encapsulant are not required to be multi-layered in the protective resin layer, and the adhesion process between the protective resin layer and the encapsulant layer and the steps of unevenness control are not performed. The laminated body for solar cells excellent in the interlayer adhesiveness with a layer, durability, and moisture resistance can be provided.

DESCRIPTION OF SYMBOLS 101 ... Plate glass 102 ... Sealing material 103 ... Slide glass 104 ... Stainless steel plate

Claims (9)

A solar cell laminate having a protective resin layer and a sealing material layer disposed in contact with the protective resin layer,
The protective resin layer satisfies the following condition (1), the sealing material layer satisfies the following condition (2), and the maximum delamination strength between the protective resin layer and the sealing material layer is 40 N / A laminate for solar cells, characterized by being 10 mm wide or more.
(1) Water vapor transmission rate per 100 μm thickness is 10 g / m ² / 24h or more (2) Consists of an olefin-based resin composition containing a compound having an alkoxysilane group   The laminate for a solar cell according to claim 1, wherein the wetting index of the surface of the protective resin layer in contact with the sealing material layer is 50 mN / m or more.   The solar cell laminate according to claim 1 or 2, wherein a main component of the resin composition constituting the protective resin layer is a polycarbonate resin or a polyester resin.   The laminated body for solar cells according to any one of claims 1 to 3, wherein the protective resin layer has a dielectric constant of 2.7 or more at 23 ° C and 1 MHz. The said olefin resin composition satisfy | fills following conditions (i) and (ii), The laminated body for solar cells of any one of Claims 1-4 characterized by the above-mentioned.
(I) A crystal melting peak temperature (Tm) of 100 ° C. or less measured at a heating rate of 10 ° C./min in differential scanning calorimetry, and a crystal melting heat of 100 ° C. or less of 10 J / g or more and 100 J / g (Ii) a crystal melting peak temperature (Tm) of 100 ° C. or higher measured at a heating rate of 10 ° C./min in differential scanning calorimetry, and a crystal melting heat of 100 ° C. or higher of 0.1 J / g or higher 70 J / g or less Laminate for a solar battery according to any one of claims 1 to 5, the water vapor permeability per thickness 100μm of the sealing material layer is equal to or less than 30g / m 2 / ^24h.   The solar cell laminate according to claim 1, wherein the total light transmittance at a thickness of 450 μm of the sealing material layer is 85% or more.   The said sealing material layer is a multilayer structure, The laminated body for solar cells of any one of Claims 1-7 characterized by the above-mentioned. The solar cell module which has the laminated body for solar cells of any one of the said Claims 1-8.

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