JP2018152618A - Solar cell module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solar cell module which has good end part adhesiveness, has excellent moisture resistance and durability, and has excellent transparency on the front surface side (a sun light receiving side) even after being exposed under high temperature and high humid conditions for a long period of time.SOLUTION: A solar cell module includes: a front surface protective layer (A); a sealing material layer (B1); solar cell elements; a sealing material layer (B2); and a rear surface protective layer (C) in this order. The sealing material layer (B2) contacts with a part of the front surface protective layer (A). Density of the sealing material layer (B1) is lower than density of the sealing material layer (B2).SELECTED DRAWING: Figure 1

Description

  The present invention relates to a solar cell module. More specifically, the present invention relates to a solar cell module that has good edge adhesion and excellent transparency on the front side (sunlight receiving side).

  In recent years, photovoltaic power generation has attracted a great deal of attention as an energy source that is clean and useful for preventing global warming, and has already begun to spread considerably. 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.

A general solar cell has a transparent and strong glass substrate or resin substrate as a front surface, and the outer periphery of a solar cell module in which a solar cell element is sealed using a sealing material and a back protection member (such as a back sheet). It is used in a form in which a sealing material or a metal frame is attached to the part, and further, a wiring, a terminal box or the like is connected.
In such a solar cell module, it is important that the solar cell elements used in various outdoor environments do not suffer damage or a decrease in insulation over a long period of time. In addition, moisture resistance at low temperatures is required. Here, with respect to moisture resistance, the influence of moisture intrusion from the side of the module is large, especially damage or damage to the solar cell element due to moisture penetration due to insufficient adhesion or adhesion at the interface between other members and the sealing material. There was a problem of causing a decrease in insulation.

  For example, Patent Document 1 discloses a first protective material, a first sealing material, a plurality of solar cells, and a second sealing material, which are protective materials on the solar light receiving surface side, as a method for suppressing moisture intrusion from the side surface of the module. A laminate forming step of forming a laminate by sequentially laminating a material and a second protective material which is a protective material on the back surface side, and a laminating step of pressing the laminate while pressing the laminate from above and below, the laminate step Has proposed a method of manufacturing a solar cell module in which the first sealing material is sealed between the first protective material and the second sealing material. The manufacturing method solves the problem that when the sealing material protruding from the protective material is removed and the sealing material is exposed on the side surface of the solar cell module, moisture easily enters from the side surface. And in order to suppress the protrusion of a 1st sealing material, making the softening temperature of a 1st sealing material higher than the softening temperature of a 2nd sealing material is disclosed.

JP 2010-177282 A

  However, Patent Document 1 discloses the softening temperature of the first sealing material for a specific mode in which the first sealing material on the solar light receiving surface side and the second sealing material on the back surface side are different materials. There is no disclosure or suggestion other than making it higher than the softening temperature of the second sealing material, and there is no description on the influence on the adhesiveness. Further, the solar cell module is required to maintain not only the initial edge adhesion but also the high edge adhesion after being exposed for a long time under high temperature and high humidity.

Furthermore, in the solar cell module, in order to prevent the cracking of the solar cell element (cell) in the laminating process at the time of manufacture, to improve the appearance of the module, to improve the utilization efficiency and long-term reliability of sunlight, The sealing material on the light receiving side is required to have high flexibility and transparency. In addition, heat resistance is particularly required for the sealing material on the back side for the purpose of suppressing increase in moisture absorption and cell displacement under high temperature conditions.
However, like the solar cell module disclosed in Patent Document 1, the softening temperature of the front-side sealing material is set to be higher for the purpose of increasing the softening temperature of the front-side sealing material. When adjusted high, the sealing material on the front side is inferior in transparency and flexibility. On the other hand, if the softening temperature of the sealing material on the back side is lowered, the heat resistance is lowered.

  The problem of the present invention is that the end part adhesion between the protective material and the sealing material is good even after being exposed to high temperature and high humidity for a long time, is excellent in moisture resistance and durability, and is on the front side (sunlight receiving side). It is in providing the solar cell module which is excellent also in transparency.

As a result of intensive studies, the present inventors have found that a solar cell module having a specific layer configuration in which a solar cell element is sealed with a sealing material layer that satisfies a predetermined requirement has good edge adhesion. In addition, the present inventors have found that it is excellent in moisture resistance and durability, and can be compatible with transparency on the front side (sunlight receiving side), and has completed the present invention.
That is, the present invention relates to the following [1] to [12].

[1] A solar cell module having a front protective layer (A), a sealing material layer (B1), a solar cell element, a sealing material layer (B2), and a back protective layer (C) in this order, and front protection A solar cell module, wherein the sealing material layer (B2) is in contact with a part of the layer (A), and the density of the sealing material layer (B1) is lower than the density of the sealing material layer (B2).
[2] The solar cell module according to [1], wherein the density of the sealing material layer (B1) is 0.85 to 0.91 g / cm ³ .
[3] The solar cell module according to [1] or [2], wherein the density of the sealing material layer (B2) is 0.88 to 0.96 g / cm ³ .
[4] The crystal melting peak temperature of the sealing material layer (B1) is lower than the crystal melting peak temperature of the sealing material layer (B2), according to any one of the above [1] to [3] Solar cell module.
[5] The solar cell module according to any one of [1] to [4], wherein the sealing material layer (B2) contains an olefin polymer as a main component.
[6] The solar cell module according to the above [5], wherein the olefin-based polymer is mainly composed of a copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms.
[7] The solar cell module according to any one of [1] to [6], wherein the sealing material layer (B2) includes a polar component.
[8] The solar cell module according to the above [7], wherein the polar component contains a polar group-containing olefin polymer as a main component.
[9] The above [1], wherein the gel fraction calculated from the mass of the xylene insoluble matter measured in accordance with ASTM-2765-95 of the sealing material layer (B2) is less than 1%. -The solar cell module in any one of [8].
[10] The diagonal length x1 from the corner of the sealing material layer (B2) in the region where the sealing material layer (B2) and the front protective layer (A) are in contact is 1 to 100 mm. The solar cell module according to any one of [1] to [9].
[11] The diagonal length from the corner of the sealing material layer (B2) in the region where the sealing material layer (B2) and the front protective layer (A) are in contact with the diagonal length x2 of the solar cell module The solar cell module according to any one of [1] to [10], wherein the ratio (x1 / x2) of the length x1 is 0.1% or more.
[12] The solar cell module according to [11], wherein x1 / x2 is 0.1 to 30.0%.

  According to the present invention, a solar cell module that has good edge adhesion even after exposure to high temperature and high humidity for a long time, excellent moisture resistance and durability, and excellent transparency on the front side (sunlight receiving side). Can provide.

It is a schematic sectional drawing which shows an example of the solar cell module of this invention. It is a schematic plan view which shows an example at the time of seeing the solar cell module of this invention from the front surface protective layer (A) side. It is the schematic which shows the measuring method of edge part peeling amount. It is the schematic which shows the preparation methods of the test sample for adhesive evaluation.

  Hereinafter, examples of embodiments of the solar cell module of the present invention will be described. However, the scope of the present invention is not limited to the embodiments described below.

In the present specification, “main component” is intended to allow other components to be included as long as the effects of the resin constituting each member of the solar cell module of the present invention are not hindered. . 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, and 100% by mass or less of the entire constituent components. It is a component that occupies a range.
Further, in this specification, for example, the notation A / B / C indicates that layers are stacked in the order of A, B, and C from the top (or from the bottom).
Further, in the present specification, the “resin composition” indicates a resin when the resin constituting the sealing material layer is one kind, and a mixture when the resin is a mixture of two or more kinds.

[Solar cell module]
FIG. 1 is a schematic cross-sectional view showing an example of the solar cell module of the present invention. In FIG. 1, a solar cell module 100 of the present invention includes a front protective layer (A) 10, a sealing material layer (B1) 12A, a solar cell element 14, and a sealing material layer (B2) 12B in order from the sunlight receiving side. The back protective layer (C) 16 is laminated, and further, a junction box (a terminal box for connecting wiring for taking out electricity generated from the solar cell element to the outside) on the lower surface of the back protective layer (C) 16 ( (Not shown) is bonded. The plurality of solar cell elements 14 are connected by 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 protective layer (C) 16 and connected to the junction box.

The solar cell module of the present invention has a front protective layer (A), a sealing material layer (B1), a solar cell element, a sealing material layer (B2) and a back protective layer (C) in this order. The sealing material layer (B2) is in contact with a part of the front protective layer (A). Since the sealing material layer (B2) is in contact with a part of the front protective layer (A), the end portion adhesion is good even after being exposed to high temperature and high humidity for a long time, and the moisture resistance and durability are excellent. A solar cell module can be obtained.
The sealing material layer (B2) is preferably in contact with at least a corner portion of the front protective layer (A) from the viewpoint of end adhesion of the module, and sealed along the outer periphery of the front protective layer (A). It is more preferable that the material layer (B2) is in contact. In this specification, “contact with the corner portion of the front protective layer (A)” is sufficient if the sealing material layer (B2) is in contact with the vicinity of the corner portion of the front protective layer (A). For example, when the front protective layer (A) is square, the sealing material layer (B2) is in contact with the four corners of the front protective layer (A). Further, “contacting along the outer periphery of the front protective layer (A)” does not mean that the outer periphery of the front protective layer (A) must be strictly aligned, and may be in the vicinity of the outer periphery. Moreover, it is a concept including not only the case where it touches in the whole outer periphery but the aspect which the one part lacks.

FIG. 2 is a schematic plan view showing an example when the solar cell module of the present invention is viewed from the front protective layer (A) side. 2A and 2B both have the same layer structure as the module shown in FIG. However, the illustration of the front protective layer (A) is omitted in FIG.
In the modules illustrated in FIGS. 2A and 2B, the module 100, the front protective layer (A) 10 (not shown in FIG. 2), and the sealing material layer (B2) 12B are all the same size. That is, in FIG. 2, the sealing material layer (B2) 12B in a region protruding from the sealing material layer (B1) 12A is in contact with the front protective layer (A).
Here, in FIGS. 2A and 2B, the diagonal length from the corner of the sealing material layer (B2) in the region where the sealing material layer (B2) 12B is in contact with the front protective layer (A). X1 and the diagonal length of the solar cell module is x2. In this case, from the viewpoint of sealing and protecting the solar cell element (cell) while the sealing material layer (B2) is in contact with a part of the front surface protective layer (A) and suppressing end peeling, the value of x1 Is preferably 1 to 100 mm, more preferably 5 to 50 mm, and even more preferably 10 to 40 mm.
From the above viewpoint, the ratio of x1 / x2 is preferably 0.1 to 30.0%, more preferably 0.5 to 20.0%, and 2.0 to 10.0%. More preferably it is.
Further, the value of x1 is an average value of measured values at all corners, and the value of x2 is a value calculated from the average value of two diagonal distances.

  The initial end peel amount in the solar cell module of the present invention is preferably less than 3 mm and more preferably less than 1 mm when the peel force (load) at the end is 30 kgf. If it is the said range, it will become difficult to produce peeling of an edge part also in a normal module manufacturing process, and the moisture resistance and durability of the obtained module will become favorable. In addition, when considering the load on the corners, such as the deformation of the module components outside the module manufacturing process and the stress generated due to the difference in thermal expansion coefficient, the initial edge peel amount is the peel force (load) at the edges. In 100 kgf, it is preferably less than 15 mm, more preferably less than 9 mm, and even more preferably less than 7 mm. Furthermore, the difference between the end peel amount after the dump heat test (temperature 85 ° C., 85% RH, 1000 hours) and the initial end peel amount is preferably less than 10 mm at a peel force (load) of 100 kgf. More preferably, it is less than 5 mm, and still more preferably less than 2 mm. If it is the said range, edge part peeling does not advance over a long period of time, and moisture resistance and durability become further favorable.

Next, each member used for the solar cell module of this invention is demonstrated.
(Front protective layer (A))
Although it does not restrict | limit especially as a front surface protective layer (A) used for this invention, For example, board | plate materials, such as glass, an acrylic resin, a polycarbonate resin, a polyester resin, and a fluorine-containing resin, Single layers, such as said resin Or a multilayer film is mentioned. Examples of the glass plate material include white plate glass, tempered glass, double tempered glass, heat ray reflective glass, and white plate tempered glass. Generally, white plate tempered glass having a thickness of about 3 to 5 mm is used. In the present invention, a glass plate material from the viewpoint of economy and mechanical strength, and a plate material having an acrylic resin or polycarbonate resin thickness of about 5 mm from the viewpoint of lightness and workability are preferably used. As the glass plate material, embossed glass whose surface is embossed is also preferable from the viewpoint of increasing the utilization efficiency of sunlight.

(Encapsulant layer)
The sealing material layers (B1) and (B2) used in the present invention are provided between the front protective layer (A) and the back protective layer (C) for the purpose of sealing and protecting the solar cell element. In the following description, the sealing material layers (B1) and (B2) may be collectively referred to as “sealing material layer”.
In the solar cell module of the present invention, the density of the sealing material layer (B1) is lower than the density of the sealing material layer (B2). When the density of the sealing material layer (B2) is higher, it is possible to achieve both transparency on the front surface side and adhesion between the front surface protective layer (A) and to improve moisture resistance in the long term. The reason why the above effect is obtained by the high density of the sealing material layer (B2) is that the tensile rigidity of the sealing material layer (B2) is improved, thereby improving the adhesiveness and the sealing material layer ( It is considered that the moisture resistance is improved by improving the crystallinity of B2).
From the viewpoint of obtaining the above effect, the density of the sealing material layer (B1) is preferably lower than the density of the sealing material layer (B2) by 0.01 g / cm ³ or more, and preferably 0.02 g / cm ³ or lower. More preferred. The density of the sealing material layer (B1) is preferably 0.85 to 0.91 g / cm ³ , and the density of the sealing material layer (B2) is preferably 0.88 to 0.96 g / cm ³ , More preferably, it is 0.90 to 0.95 g / cm ³ . When the density of the sealing material layer is within the above range, a solar cell module having particularly excellent transparency on the front side can be obtained.
The density of the sealing material layer can be adjusted by selecting a material used for the sealing material layer. The material used for a sealing material layer is demonstrated below.

The sealing material layer used in the present invention is not particularly limited. Specifically, ethylene-vinyl acetate copolymer (EVA), olefin polymers represented by polyethylene (PE), polypropylene (PP) and ionomer (IO), and polyvinyl butyral (PVB) are the main components. And a sealing material layer.
In the present invention, an encapsulant layer containing as a main component at least one of the olefin polymers, particularly at least one of the olefin polymers shown in the following (b1) to (b4) is preferable. From the viewpoint of moisture resistance (water vapor barrier property) and hydrolysis resistance (long-term adhesion with the front protective layer (A)), at least the encapsulant layer (B2) is mainly composed of an olefin polymer. It is preferable that the sealing material layers (B1) and (B2) have an olefin polymer as a main component. Here, from the viewpoints of flexibility of the obtained sealing material layer, a small number of fish eyes (gel), a small number of corrosive substances (such as acetic acid) in the circuit, and economic efficiency, the olefin polymer is as follows. What has (b1) or (b2) as a main component to describe is preferable, and what has (b1) as a main component is especially preferable at the point which is excellent in a low-temperature characteristic.

(B1)
(B1) is a copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms. These copolymerization forms (random, block, etc.), branching, branching degree distribution and three-dimensional structure are not particularly limited, and a polymer having an isotactic, atactic, syndiotactic or mixed structure thereof can be obtained. 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.
Propylene, 1-butene, 1-hexene, and 1-octene are preferably used as the α-olefin copolymerized with ethylene from the viewpoint of industrial availability, various characteristics, economy, and the like. Octene is more preferred. 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 all monomers in the copolymer (b1) of ethylene and an α-olefin having 3 to 20 carbon atoms. The monomer unit based on an α-olefin having 3 to 20 carbon atoms is usually 2 mol% or more, preferably 2 to 40 mol%, more preferably 3 to 30 mol%, and still more preferably 5 to the 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 (b1) 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 units is preferably 20 mol% or less when the total monomer units in the copolymer (b1) of ethylene and an α-olefin having 3 to 20 carbon atoms is 100 mol%. More preferably, it is 15 mol% or less.
The three-dimensional structure, branching, branching degree distribution and molecular weight distribution of the copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms are not particularly limited. The copolymer having such an advantage generally has good mechanical properties.

  The melt flow rate (MFR) of the copolymer (b1) of ethylene and an α-olefin having 3 to 20 carbon atoms used in the present invention is not particularly limited, but the solar cell element (cell) is sealed. From the viewpoint of adhesion and ease of turning around, MFR (JIS K7210, temperature: 190 ° C., load: 21.18 N) is usually about 0.1 to 100 g / 10 minutes, preferably 0.2. -50 g / 10 min, more preferably 0.5-50 g / 10 min, still more preferably 0.5-30 g / 10 min.

  The production method of the copolymer (b1) of ethylene and an α-olefin having 3 to 20 carbon atoms is not particularly limited, and a known polymerization method using a known olefin polymerization catalyst can be employed. For example, a slurry polymerization method, a solution polymerization method, a gas phase polymerization method 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.

The heat of crystal fusion measured at a heating rate of 10 ° C./min in the differential scanning calorimetry of the copolymer of ethylene and α-olefin having 3 to 20 carbon atoms used in the present invention is 0 to 130 J / g. It is preferable that Within such a range, the flexibility and transparency (total light transmittance) of the obtained sealing material layer are ensured. Further, considering the difficulty of blocking the raw material pellets in a high temperature state such as summer, the heat of crystal melting is preferably 5 to 70 J / g, more preferably 10 to 65 J / g.
The heat of crystal fusion can be measured at a heating rate of 10 ° C./min in accordance with JIS K7122 using a differential scanning calorimeter.

  Specific examples of the copolymer (b1) of ethylene and an α-olefin having 3 to 20 carbon atoms used in the present invention include trade names “Engage” and “affinity” manufactured by Dow Chemical Co., Ltd. “Affinity”, “Infuse”, trade name “Exact” manufactured by ExxonMobil Corp., trade names “TAFMER H”, “Tuffmer A” manufactured by Mitsui Chemicals, Inc. "TAFMER A)", "TAFMER P", LG Chemical's trade name "LUCENE", Nippon Polyethylene's trade name "Kernel", Prime Polymer's product Names “Evolue P”, “Evolue H”, “NEOZEX”, etc. It can be exemplified.

(B2)
(B2) 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 monomers copolymerizable with propylene include ethylene, 1-butene, 1-hexene, 4-methyl-pentene-1, 1-octene and other α-olefins having 4 to 12 carbon atoms and divinylbenzene, Examples include dienes such as 1,4-cyclohexadiene, dicyclopentadiene, cyclooctadiene, and ethylidene norbornene.
In the present invention, ethylene and 1-butene are preferably used as the α-olefin copolymerized with propylene from the viewpoints of industrial availability, various characteristics, economy, and the like. 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 a copolymer of propylene and other monomers copolymerizable with the propylene (b2) The monomer units based on other monomers copolymerizable with propylene are usually 2 mol% or more, preferably 2 to 40 mol%, more preferably 3 to the total monomer units in 30 mol%, 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 quantitatively analyzed by a known method, for example, a nuclear magnetic resonance (NMR) measuring device or other instrumental analyzer.

  Although the melt flow rate (MFR) of (b2) used for this invention is not restrict | limited in particular, from the viewpoint of the adhesiveness at the time of sealing a solar cell element (cell), or a wraparound ease, it is normal. , MFR (JIS K7210, temperature: 230 ° C., load: 21.18 N) is about 0.5 to 100 g / 10 minutes, preferably 2 to 50 g / 10 minutes, more preferably 3 to 30 g / 10 minutes.

  The production method of (b2), which is a copolymer of propylene and another monomer copolymerizable with propylene, or a homopolymer of propylene 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 typified by a Ziegler-Natta type catalyst, a single site catalyst typified 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 (b2) used in the present invention include propylene-butene random copolymers, propylene-ethylene random copolymers, propylene-ethylene-butene-1 copolymers, and the like. Are trade names “TAFMER XM”, “NOTIO”, Sumitomo Chemical Co., Ltd., “TAFFCELLEN”, and Prime Polymer Co., Ltd. “Prime TPO”, trade name “VERSIFY” manufactured by Dow Chemical Co., Ltd., trade name “VistaMAXX” manufactured by ExxonMobil Corp., and the like can be exemplified.

(B3)
(B3) is a metal salt of a copolymer composed of an α-olefin such as ethylene or propylene and an aliphatic unsaturated carboxylic acid (preferred metals are Zn, Na, K, Li, Mg, etc.).
Specific products include, for example, a trade name “HIMILAN” manufactured by Mitsui Chemicals, Inc., and a product name “AMPLIFY IO” manufactured by Dow Chemical Co., Ltd.

(B4)
(B4) is an ethylene-based copolymer composed of ethylene and at least one monomer selected from vinyl acetate, aliphatic unsaturated carboxylic acid, and aliphatic unsaturated 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 esters of alcohols having 1 to 8 carbon atoms such as methyl, ethyl, propyl, and butyl. In the present invention, the copolymer is not limited to the above-described two-component copolymer, but a three-component or more multi-component copolymer (for example, ethylene and an aliphatic unsaturated carboxylic acid and an aliphatic unsaturated copolymer) with a third component added. It may be a ternary or higher copolymer suitably selected from saturated carboxylic acid esters). Here, the content of the monomer unit copolymerized with ethylene is usually 2 mol% or more, preferably 2 to 40 mol%, more preferably, with respect to all monomer units in the copolymer. 3 to 30 mol%.

  The encapsulant layer used in the present invention has a single layer or a laminated structure, but a laminated structure is preferable in order to achieve the properties required for the encapsulant layer in a balanced manner. Here, the properties generally required for the sealing material layer include flexibility and impact resistance for protecting the solar cell element, heat resistance when the solar cell module generates heat, solar light to the solar cell element. For efficient delivery of light (total light transmittance, etc.), adhesion to various adherends (glass, back protective layer, etc.), durability, dimensional stability, flame resistance, water vapor barrier property, economy Sex and so on. Above all, importance is attached to the balance between flexibility, heat resistance and transparency, and economy.

Although the crystal melting peak temperature (Tm) of the olefin polymer is preferably less than 100 ° C., an amorphous polymer that does not express the crystal melting peak temperature, that is, an amorphous polymer is also applicable (hereinafter referred to as amorphous). And olefin polymers having a crystal melting peak temperature of less than 100 ° C.). Considering blocking of raw material pellets, the crystal melting peak temperature is preferably 30 to 95 ° C, more preferably 45 to 80 ° C, and further preferably 50 to 80 ° C.
Further, when emphasizing the flexibility of the sealing material layer, an olefin polymer having a crystal melting peak temperature (Tm) of 100 ° C. or higher is mixed with an olefin polymer having a crystal melting peak temperature (Tm) of less than 100 ° C. It is preferable to use it. The upper limit of the crystal melting peak temperature (Tm) of the olefin polymer to be mixed is not particularly limited, but it is 145 in consideration of the thermal deterioration of the solar cell element (cell) and the lamination temperature at the time of manufacturing the solar cell module. It is about ℃. In this invention, since the lamination temperature at the time of producing a solar cell module can be lowered and the solar cell element (cell) is hardly thermally deteriorated, the upper limit of the crystal melting peak temperature (Tm) of the olefin polymer to be mixed. The value is preferably 130 ° C, more preferably 125 ° C.
When the sealing material layer has a laminated structure, it has at least one layer containing an olefin polymer having a crystal melting peak temperature of less than 100 ° C. and an olefin polymer having a crystal melting peak temperature of 100 ° C. or more. It is preferable that the layer having the largest composition ratio in the stacked structure is more preferably the above layer.

  Here, as reference values for the crystal melting peak temperature, general-purpose high-density polyethylene (HDPE) is about 130 to 145 ° C., and low-density polyethylene (LDPE) and linear low-density polyethylene (LLDPE) are 100 to 125 ° C. The general-purpose homopolypropylene is about 165 ° C., and the general-purpose propylene-ethylene random copolymer is about 130 to 150 ° C. The crystal melting peak temperature can be measured at a heating rate of 10 ° C./min according to JIS K7121 using a differential scanning calorimeter.

As described above, the sealing material layer preferably includes at least one layer containing an olefin polymer having a crystal melting peak temperature of less than 100 ° C. and an olefin polymer having a crystal melting peak temperature of 100 ° C. or higher. .
The content of both olefinic polymers in the above layer is not particularly limited, but considering the flexibility, heat resistance, transparency, etc. of the resulting sealing material layer, mixing of both olefinic polymers The (containing) mass ratio (olefin polymer having a crystal melting peak temperature of less than 100 ° C./olefin polymer having a crystal melting peak temperature of 100 ° C. or higher) is preferably 99 to 50/1 to 50, more preferably 98. -60/2 to 40, more preferably 97 to 70/3 to 30, particularly preferably 97 to 80/3 to 20, and most preferably 97 to 90/3 to 10. However, the total of both olefin polymers is 100 parts by mass. When the mixed (containing) mass ratio is within the above range, the encapsulant layer having a good balance of flexibility, heat resistance, transparency and the like is likely to be obtained.

  The olefin polymer having a crystal melting peak temperature of 100 ° C. or higher may be appropriately selected in consideration of desired properties, but in the present invention, the balance between heat resistance, flexibility, low temperature properties, etc. is excellent. The ethylene-α-olefin block copolymer described in 1) can be used.

<Ethylene-α-olefin block copolymer>
The block structure of the ethylene-α-olefin block copolymer is not particularly limited, but from the viewpoint of balancing such as flexibility, heat resistance, transparency, comonomer content, crystallinity, density, crystal A multi-block structure containing two or more segments or blocks having different melting peak temperatures (Tm) or glass transition temperatures (Tg) is preferable. Specific examples include a completely symmetric block, an asymmetric block, and a tapered block structure (a structure in which the ratio of the block structure gradually increases in the main chain). Regarding the structure and production method of the copolymer having the multi-block structure, International Publication No. 2005/090425 (WO2005 / 090425), International Publication No. 2005/090426 (WO2005 / 090426), and International Publication No.2005. / 090427 pamphlet (WO2005 / 090427) or the like can be employed.

Next, the ethylene-α-olefin block copolymer having the multi-block structure will be described in detail below.
The ethylene-α-olefin block copolymer having a multiblock structure can be suitably used in the present invention, and an ethylene-octene multiblock copolymer having 1-octene as a copolymerization component as an α-olefin is preferable. As the block copolymer, an almost non-crystalline soft segment copolymerized with a large amount of octene component (about 15 to 20 mol%) with respect to ethylene and a small amount of octene component with respect to ethylene (about 2 mol%). Less) a multiblock copolymer in which two or more highly crystalline hard segments each having a copolymerized crystal melting peak temperature of 110 to 145 ° C. are present. By controlling the chain length and ratio of these soft segments and hard segments, both flexibility and heat resistance can be achieved.
As a specific example of the copolymer having the multi-block structure, trade name “Infuse” manufactured by Dow Chemical Co., Ltd. may be mentioned.

The surface of the sealing material layer used in the present invention is bonded to various adherends such as a front protective layer (A), a solar cell element, and a back protective layer (C) along with handling properties and ease of bleeding. Therefore, important functions as a sealing material for solar cell modules are required. From this viewpoint, in the present invention, it is preferable that the sealing material layer includes a polar component. In particular, when the encapsulant layer (B2) contains a polar component, a module having excellent adhesion to various adherends and excellent end-part adhesion can be obtained.
The polar component is mainly composed of a silane coupling agent, a polar group-containing olefin polymer such as a silane-modified ethylene resin, an acid-modified ethylene resin, an acrylic-modified ethylene resin, and an epoxy-modified ethylene resin. Etc. As a sealing material layer containing such a polar component, for example, the above-described (b1) to (b4) are added with a silane coupling agent described later, or a kind of polar group-containing olefin polymer. A sealing material layer in which the following silane-modified ethylene resin is mixed is preferably used. When the sealing material layer has a laminated structure, it is preferable to have at least one layer obtained by mixing the above-described (b1) to (b4) with a silane-modified ethylene-based resin. Moreover, when a sealing material layer is a laminated structure, it is preferable that an outermost layer is a layer containing the said polar component from a viewpoint of the adhesiveness to the said various to-be-adhered body.

<Silane-modified ethylene resin>
The silane-modified ethylene resin used in the present invention can be 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.

  Although it does not restrict | limit especially 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 can be used alone or in combination of two or more, and in particular, the copolymer of ethylene and the α-olefin having 3 to 20 carbon atoms mentioned in the above (b1) is preferably used. Can do.

In this invention, since transparency and a softness | flexibility become favorable, an ethylene-type resin with a low density is used suitably. Specifically, low-density polyethylene preferably having a density of 0.850~0.930g / cm ^3, density is more preferably linear low density polyethylene 0.870~0.920g / cm ^3. Moreover, a low density polyethylene and a high density polyethylene can be used in combination. By using in combination, the balance of transparency, flexibility and heat resistance can be adjusted relatively easily.

  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 Examples include butoxysilane, vinyltripentyloxysilane, vinyltriphenoxysilane, vinyltribenzyloxysilane, vinyltrimethylenedioxysilane, vinyltriethylenedioxysilane, vinylpropionyloxysilane, vinyltriacetoxysilane, and vinyltricarboxysilane It is done. These vinyl silane compounds can be used alone or in combination of two or more. In the present invention, vinyltrimethoxysilane is preferably used from the viewpoints of reactivity, adhesiveness and color tone.

  The amount of the vinylsilane compound added is not particularly limited, but is usually about 0.01 to 10.0 parts by mass, preferably 0.3 to 100 parts by mass with respect to 100 parts by mass of the ethylene resin used. It is 8.0 mass parts, More preferably, it is 1.0-5.0 mass parts.

  Although it does not restrict | limit especially as a radical generator, For example, 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 oxides; t-butyl pero Siacetate, t-butyl peroxy-2-ethylhexanoate, t-butyl peroxypivalate, t-butyl peroxy octoate, t-butyl peroxyisopropyl carbonate, t-butyl peroxybenzoate, di-t -Peroxyesters such as butyl peroxyphthalate, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, 2,5-dimethyl-2,5-di (benzoylperoxy) hexyne-3; Examples include organic peroxides such as ketone peroxides such as methyl ethyl ketone peroxide and cyclohexanone peroxide, or azo compounds such as azobisisobutyronitrile and azobis (2,4-dimethylvaleronitrile). These radical generators can be used alone or in combination of two or more.

  Moreover, the addition amount of the radical generator in the silane-modified ethylene resin 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 ethylene resin used. , Preferably it is 0.02-1.0 mass part, More preferably, it is 0.03-0.5 mass part. Furthermore, the residual amount of radical generator is preferably 0.001% by mass or less in the resin composition used for the sealing material layer. When such a radical generator remains in the resin composition, gelation may be caused by heating. In addition, gelation may include not only the presence of the radical generator in the encapsulant layer but also partly gelated when the encapsulant layer is produced. Since the fluidity of the stopping material layer is hindered and the reliability of the solar cell module is impaired, the gelation should be less. Accordingly, the gel fraction of the resin composition used for the sealing material layer is preferably less than 30%, more preferably 10% or less, further preferably 5% or less, and 0%. It is particularly preferred.

It is preferable that the resin composition used for the sealing material layer does not substantially contain a silanol condensation catalyst that promotes a condensation reaction between silanols. Specific examples of the silanol condensation catalyst include dibutyltin diacetate, dibutyltin dilaurate, dibutyltin dioctate, dioctyltin dilaurate and the like.
Here, “substantially not contained” is usually 0.05 parts by mass or less, preferably 0.03 parts per 100 parts by mass of the silane-modified ethylene resin in the resin composition used for the encapsulant layer. The amount is not more than part by mass, and more preferably 0.00 part by mass.

  The reason why it is preferable not to substantially contain a silanol condensation catalyst is that, in the present invention, the silanol crosslinking reaction is not allowed to proceed actively, and the polar group such as a silanol group grafted to the ethylene resin to be used is attached. Bonded by interaction such as hydrogen bonding or covalent bonding with body (glass, various plastic sheets (appropriate surface treatment such as corona treatment, wetting index of 50 mN / m or more is preferably used), metal, etc.) This is to express sex.

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

<Silane coupling agent>
The silane coupling agent is useful for improving adhesion to the front protective layer (A), the solar cell element, the back protective layer (C), and the like. Examples thereof include a vinyl group, an acryloxy group, and a methacryloxy group. Examples thereof include compounds having a hydrolyzable group such as an alkoxy group in addition to an unsaturated group such as, an amino group, and an epoxy group.
As the silane coupling agent, N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane, N- (β-aminoethyl) -γ-aminopropylmethyldimethoxysilane, γ-aminopropyltriethoxysilane, γ Examples thereof include glycidoxypropyltrimethoxysilane and γ-methacryloxypropyltrimethoxysilane. These silane coupling agents can be used alone or in combination of two or more. In the present invention, γ-glycidoxypropyltrimethoxysilane and γ-methacryloxypropyltrimethoxysilane are preferably used because of good adhesiveness and less discoloration such as yellowing.
The addition amount of the silane coupling agent is usually about 0.1 to 5 parts by mass, preferably 0.2 to 3 parts by mass with respect to 100 parts by mass of the resin composition used for the sealing material layer. is there. In addition, similar to the silane coupling agent, a coupling agent such as an organic titanate compound can be effectively used.

<Additive>
Various additives can be added to the resin composition used for the sealing material layer, if necessary. Examples of the additive include an antioxidant, an ultraviolet absorber, a weather resistance stabilizer, a light diffusing agent, a heat radiating agent, a nucleating agent, a pigment (for example, titanium oxide, carbon black, etc.), a flame retardant, and a discoloration preventing agent. Is mentioned. In the present invention, the resin composition constituting the encapsulant layer is preferably added with at least one selected from an antioxidant, an ultraviolet absorber and a weathering stabilizer for reasons described later.
Further, in the present invention, it is not necessary to add a crosslinking agent or a crosslinking aid to the resin composition used for the encapsulant layer, but it does not exclude the addition, for example, requires high heat resistance. In such a case, a crosslinking agent and / or a crosslinking aid can be blended.

(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 exemplified.
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 the bisphenol 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 can be exemplified.

  Examples of the high molecular phenolic compound 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- Examples include 4′-hydroxybenzyl) -s-triazine-2,4,6- (1H, 3H, 5H) trione, tocopherol (vitamin E) and the like.

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

The phosphite system includes 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-phospha Phenanthrene, cyclic neopentanetetraylbis (2,4-di-tert-butylphenyl) phosphite, cyclic neopentanetetraylbis (2,6-di-tert-methylphenyl) phosphite, 2,2- Examples thereof include methylene bis (4,6-tert-butylphenyl) octyl phosphite.
The said antioxidant can be used individually by 1 type or in combination of 2 or more types.

In the present invention, monophenolic, bisphenolic, polymeric phenolic and other phenolic and phosphite antioxidants are preferably used in view of the effects of antioxidants, thermal stability, economy, etc. More preferably, they are used in combination.
The addition amount of the antioxidant is usually about 0.1 to 1 part by weight, preferably 0.2 to 0.5 parts by weight with respect to 100 parts by weight of the resin composition used for the sealing material layer. It is.

<Ultraviolet absorber>
As the ultraviolet absorber, various commercially available products can be applied, and various types such as benzophenone, benzotriazole, triazine, and salicylic acid ester can be exemplified.
Examples of the benzophenone ultraviolet absorber include 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-2′-carboxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2-hydroxy-4-n-dodecyl. Oxybenzophenone, 2-hydroxy-4-n-octadecyloxybenzophenone, 2-hydroxy-4-benzyloxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone, 2-hydroxy-5-chlorobenzophenone, 2,4 Examples include -dihydroxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2,2 ', 4,4'-tetrahydroxybenzophenone.

Benzotriazole-based UV absorbers include hydroxyphenyl-substituted benzotriazole compounds, 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.
Examples of the triazine ultraviolet absorber 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 said ultraviolet absorber can be used individually by 1 type or in combination of 2 or more types.

  The amount of the ultraviolet absorber added is usually about 0.01 to 2.0 parts by mass, preferably 0.05 to 0.5 parts per 100 parts by mass of the resin composition used for the encapsulant layer. Part by mass.

<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. 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. In addition to hindered amines, there are those that function as light stabilizers, but they are often colored and are not preferred for the encapsulant layer used in 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) sebacate, 2- (3 , 5-Di-tert-4- Mud alkoxybenzylacetic) -2-n-butyl malonic acid bis (1,2,2,6,6-pentamethyl-4-piperidyl), and others. The said hindered amine light stabilizer can be used individually by 1 type or in combination of 2 or more types.

  The addition amount of the hindered amine light stabilizer is usually about 0.01 to 0.5 parts by weight, preferably 0.05 to 100 parts by weight of the resin composition used for the sealing material layer. 0.3 parts by mass.

  Since the sealing material layer (B2) used on the back protective layer (C) side is located on the back side of the solar cell element, it is more transparent (total light than the sealing material layer (B1) used on the front protective layer (A) side. (Transmittance) may not be very important. Therefore, when the white pigment is contained in the sealing material layer (B2) and the light incident from the front protective layer side of the solar cell module is transmitted through the solar cell element for a part of the light, the light is reflected. It is also a preferable form to provide light reflectivity mainly for the purpose of re-entering the solar cell element and effectively using light. Furthermore, the designability and decorativeness of the solar cell module can be improved by imparting light-shielding properties by various colors such as blackening and bluening.

Here, examples of the white pigment include metal oxides such as titanium oxide, zinc oxide, silicon oxide, and aluminum oxide, and inorganic compounds such as calcium carbonate and barium sulfate. These white pigments can be used alone or in combination of two or more. In the present invention, titanium oxide, zinc oxide, and calcium carbonate can be suitably used. In particular, titanium oxide is preferably used because it can efficiently impart light reflectivity with a small amount of addition.
In order to improve the power generation efficiency by light reflection, the average value of the reflectance at 500 to 700 nm with the absorption intensity of a general solar cell is preferably 50% or more, more preferably 70% or more. Preferably, it is 80% or more, more preferably 90% or more.

  It is preferable that the sealing material layers (B1) and (B2) used in the present invention are not substantially crosslinked. When the encapsulant layer does not contain a volatile component such as a crosslinking agent or a crosslinking aid, since outgas is less generated during the production of the solar cell module, the occurrence of blistering at a hot spot or the like is less likely to occur. In addition, it is possible to obtain a solar cell module having a good appearance, which hardly causes a yellowing phenomenon due to a crosslinking agent during long-term use. Here, that the encapsulant layer is not substantially crosslinked means that the gel fraction of the encapsulant layer calculated from the mass of the xylene insoluble matter measured in accordance with ASTM-2765-95 is less than 30%. It means that. The gel fraction of the sealing material layer is preferably less than 10%, more preferably less than 5%, and even more preferably less than 1%.

The flexibility of the sealing material layer is not particularly limited, and can be appropriately adjusted in consideration of the shape and thickness of the applied solar cell, 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 layer is preferably 1 to 2000 MPa. Protection and flexibility of solar cell elements, handling properties, prevention of blocking between sheet surfaces, or weight reduction in solar cell modules (usually using thin film glass (approximately 1.1 mm in solar cell modules of about 3 mm) or glassless In view of the above, it is more preferably 5 to 500 MPa, and further preferably 5 to 300 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.

  The heat resistance of the encapsulant layer is affected by various characteristics of the olefin polymer used (crystal melting peak temperature, crystal melting heat, MFR, molecular weight, etc.), and can be adjusted by appropriately selecting these. In particular, the crystal melting peak temperature and molecular weight of the olefin polymer are strongly influenced. Generally, a solar cell module may be heated to about 85 ° C. due to heat generated during power generation or radiant heat of solar light. However, if the crystal melting peak temperature is 100 ° C. or higher, the sealing used in the present invention. Since the heat resistance of a material layer can be ensured, it is preferable.

  The MFR (JIS K7210, temperature: 190 ° C., load: 21.18 N) of the sealing material layer is about 0.1 to 20 g / 10 minutes, preferably 0.2 to 10 g / 10 minutes, more preferably. Is 0.5-5 g / 10 min. When the MFR of the encapsulant layer is in the above range, it is preferable from the viewpoint of adhesion and ease of wrapping when the solar cell element (cell) is sealed, and has excellent edge adhesion and excellent moisture resistance and durability. It can be set as a solar cell module.

  The total light transmittance (JIS K7105) of the encapsulant layer used in 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 element. However, it is preferably not less than 85%, more preferably not less than 88% in consideration of the photoelectric conversion efficiency of the solar cell and handling properties when various members are overlaid. More preferably, it is 90% or more. In particular, from the above viewpoint, the total light transmittance of the sealing material layer (B1) is preferably 88% or more, and more preferably 90% or more.

The flexibility, heat resistance, and transparency of the sealing material layer used in the present invention tend to be contradictory. Specifically, if the crystallinity of the resin composition used for the sealing material layer is excessively decreased in order to improve flexibility, the heat resistance decreases and becomes insufficient. On the other hand, if the crystallinity of the resin composition used for the encapsulant layer is excessively improved in order to improve the heat resistance, the transparency is lowered and becomes insufficient.
Considering these balances, the vibrational frequency 10 Hz and the storage elastic modulus (E ′) at a temperature of 20 ° C. in dynamic viscoelasticity measurement as an index of flexibility, and heating in differential scanning calorimetry for an olefin polymer as an index of heat resistance. In order to satisfy all of the flexibility, heat resistance and transparency when using the total light transmittance as the crystal melting peak temperature measured at a rate of 10 ° C./min and the transparency index, the above three indices However, it is preferable that the storage elastic modulus (E ′) is 1 to 2000 MPa, the crystal melting peak temperature is 100 ° C. or higher, and the total light transmittance is 85% or higher, and the storage elastic modulus (E ′) is 5 to 500 MPa. More preferably, the peak temperature is 102 to 150 ° C. and the total light transmittance is 85% or more, the storage elastic modulus (E ′) is 5 to 300 MPa, and the crystal melting peak temperature is 105 to 13. More preferably, it is 0 ° C. and the total light transmittance is 88% or more.

The sealing material layer used in the present invention preferably has a crystal melting peak temperature (Tm) of the sealing material layer (B1) lower than a crystal melting peak temperature of the sealing material layer (B2). Thereby, it becomes difficult to produce appearance abnormalities such as cell cracks in the laminating process at the time of module manufacture and irregularities on the back protective layer (C) side after laminating. Furthermore, the transparency on the front side of the module is increased, and there is an effect that it is easy to maintain long-term transparency.
From this viewpoint, the crystal melting peak temperature of the sealing material layer (B1) is preferably 5 ° C. or more, more preferably 10 ° C. or more lower than the crystal melting peak temperature of the sealing material layer (B2). The crystal melting peak temperature (Tm) can be measured according to JIS K7121, and specifically can be measured by the method described in the examples.

Sealing material layer used in the present invention (B1), (B2), respectively, the temperature 40 ° C., measured at RH 90%, water vapor transmission rate in terms of thickness 100μm is preferably not more than 200g ^/ m 2 ^/ 24hr, more preferably 100g ^/ m 2 ^/ 24hr, more preferably not more than ^50g / m 2 / 24hr. By water vapor permeability of the sealing material layer is not more than 200g ^/ m 2 / 24hr, the solar cell module of the present invention becomes excellent in moisture resistance and durability. Specifically, the water vapor transmission rate can be measured by the method described in Examples.

<Method for producing sealing material>
Next, the manufacturing method of the sealing material used for a sealing material layer is demonstrated. A sealing material is obtained using the resin composition which comprises a sealing material layer.
The shape of the sealing material is not particularly limited, and may be liquid or sheet-like, but is preferably sheet-like from the viewpoint of handleability.
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, an extrusion casting method using a T die is preferably used from the viewpoints of handling properties and productivity. 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 used, but is generally 130 to 300 ° C, preferably 150 to 250 ° C.
The thickness of the 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 0.7 mm or less. More preferably, it is 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. May be supplied after being manufactured. It is also possible to prepare and supply a master batch in which only the additive is previously concentrated in the resin. 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 process of laminating solar cell elements, air handling properties and air Embossing and various unevenness (cone, pyramid shape, hemispherical shape, etc.) processing can be performed for the purpose of improving the ease of punching.
Further, for the purpose of improving the adhesion to various adherends, the surface can be subjected to various surface treatments such as corona treatment, plasma treatment and primer treatment. Here, as a standard of the surface treatment amount, the wet index is preferably 50 mN / m or more, and more preferably 52 mN / m or more. The upper limit of the wetting index is generally about 70 mN / m.

The encapsulant used in the present invention is a single layer or a laminated structure, but in order to achieve the properties required for the encapsulant as exemplified below in a balanced manner, from a plurality of layers having different composition contents and composition ratios. The laminated structure is preferably a laminated structure in which coextrusion is performed with a multilayer die using an extruder at that time.
Examples of the laminated structure composed of the plurality of layers include at least a laminated structure having a soft layer and a hard layer, which will be described later. For example, the following laminated structure is preferably used.
(1) Two types, three layers; specifically, soft layer / hard layer / soft layer, hard layer / soft layer / hard layer, adhesive layer / hard layer / adhesive layer, adhesive layer / soft layer / adhesive layer, Soft layer / recycled additive layer / soft layer, etc.
(2) Two types of two-layer configuration; specifically, soft layer / hard layer, soft layer (I) / soft layer (II), adhesive layer / soft layer, adhesive layer / hard layer, soft layer / soft layer, Such,
(3) 3 types, 3 layers; specifically, soft layer / adhesive layer / hard layer, soft layer (I) / hard layer / soft layer (II), soft layer (I) / soft layer / soft layer ( II), adhesive layer (I) / hard layer / adhesive layer (II), adhesive layer (I) / soft layer / adhesive layer (II), etc.
(4) 3 types and 5 layers; specifically, soft layer / adhesive layer / hard layer / adhesive layer / soft layer, hard layer / adhesive layer / soft layer / adhesive layer / hard layer, soft layer / regeneration additive layer / Hard layer / regeneration additive layer / soft layer, and soft layer / regeneration additive layer / hard layer / regeneration additive layer / hard layer.

In the present invention, from the viewpoint of balance between flexibility, heat resistance, transparency, and economy, soft layer / hard layer / soft layer, hard layer / soft layer / hard layer, adhesive layer / hard layer / adhesive layer, adhesion (1) Two types and three layers represented by layer / soft layer / adhesive layer, soft layer / regeneration additive layer / soft layer, etc. are preferably used. Of the two types and three-layer configuration of (1) above, the adhesive layer / soft layer / adhesive layer or soft layer / regeneration additive layer / soft layer is particularly preferable.
In addition, an intermediate | middle layer is a layer formed from the viewpoints, such as increasing the thickness of a sealing material and improving a desired performance, for example, is formed from the resin composition which has an olefin resin as a main component.
The regeneration additive layer is provided from the viewpoint of economic rationality and effective utilization of resources, and is formed from a resin composition that is regenerated and added with trimmings (ears) that occur during film formation of sealing materials and slit processing, for example. Layer.
The adhesive layer is provided from the viewpoint of improving adhesion to adjacent layers and adherends, such as carboxyl group, amino group, imide group, hydroxyl group, epoxy group, oxazoline group, thiol group and silanol group. It is a layer formed from a resin composition containing a resin modified with a polar group or a tackifying resin.
Examples of the additive include a silane coupling agent, an antioxidant, an ultraviolet absorber, a weathering stabilizer, a light diffusing agent, a heat radiating agent, a nucleating agent, a pigment, a flame retardant, a discoloration preventing agent, a crosslinking agent, and a crosslinking aid. Is mentioned.

  Here, the soft layer is 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, preferably less than 100 MPa, more preferably 5 to 50 MPa. Is a layer having a storage elastic modulus (E ′) of preferably 100 MPa or more, more preferably 200 to 800 MPa. Of the two types and three layers of the above (1), in particular, an adhesive layer / soft layer / adhesive layer is preferably used. Adopting such a laminated structure is preferable because it is possible to relatively easily realize both the protection of the solar cell element and the adhesion between the front protective layer and the rear protective layer.

  The thickness of the soft layer in close contact with the solar cell element is not particularly limited, but is preferably 0.005 mm or more in consideration of the protection of the solar cell element, the wraparound property of the resin, and the like. More preferably, it is -0.6 mm. The thickness of each soft layer may be the same or different. Further, the thickness of the hard layer is not particularly limited, but is preferably 0.025 mm or more and 0.05 to 0.8 mm from the viewpoint of handling properties as a whole sealing material. More preferred.

When the sealing material used in the present invention is produced in a sheet shape, still another base film (for example, stretched polyester film (OPET), stretched polypropylene film (OPP) or ethylene-tetrafluoroethylene copolymer (ETFE). ), Polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), and various weathering films such as acrylic) and the like, and extrusion lamination, coextrusion, sand lamination, and the like.
By laminating the encapsulant layer made of the encapsulant and various layers, it is possible to relatively easily adjust necessary characteristics, economy, and the like according to improvement in handling properties and lamination ratio.

(Solar cell element)
The solar cell element used in the present invention is not particularly limited, but generally, at least one surface is arranged in close contact with the sealing material layer and wired.
For example, single crystal silicon type, polycrystalline silicon type, amorphous silicon type, gallium-arsenic, copper-indium-selenium, copper-indium-gallium-selenium, cadmium-tellurium, etc. III-V and II-VI group compound semiconductors Type, dye-sensitized type, and organic thin film type. In the present invention, single crystal silicon type and polycrystalline silicon type solar cells are preferably used.

(Back protective layer (C))
The back protective layer (C) used in the present invention is not particularly limited, but specifically, polyester resins (polyethylene terephthalate (PET), polyethylene naphthalate (PEN), etc.), fluorine resins (polyethylene) Tetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), ethylene-tetrafluoroethylene copolymer (ETFE), polychloro Trifluoroethylene (PCTFE), polyvinylidene fluoride (PVDF) and polyvinyl fluoride (PVF)), polyolefin resins (polyethylene (PE), polypropylene (PP), various α-olefin copolymers, ethylene-vinyl acetate co Heavy (EVA), ethylene-ethyl acrylate copolymer (EEA), ethylene-acrylic acid copolymer (EAA) and ethylene-methacrylic acid copolymer (EMAA), etc., cyclic olefin resin (COP, COC, etc.) , Polystyrene resins (acrylonitrile-styrene copolymer (AS), acrylonitrile-butadiene-styrene copolymer (ABS), acrylonitrile-styrene-acrylic rubber copolymer (ASA), syndiotactic polystyrene (SPS), etc.), Polyamide (PA), polycarbonate (PC), polymethyl methacrylate (PMMA), modified polyphenylene ether (modified PPE), polyphenylene sulfide (PPS), polyether sulfone (PES), polyphenyl sulfone (PPSU), poly Electrically insulating materials such as polyetheretherketone (PEEK), polyetherimide (PEI), polyimide (PI) and biopolymers (polylactic acid, isosorbide polymer, polyamide polymer, polyester polymer, polyolefin polymer, etc.) The base material sheet (or base material film) formed by these is mentioned.

In the present invention, polyester-based resins, polyolefin-based resins, and fluorine-based resins are suitably used as the material for the base sheet from the viewpoints of adhesion to the sealing material layer, mechanical strength, durability, economy, and the like.
Here, the production method of the base sheet or base film is not particularly limited, but representative examples include an extrusion casting method, a stretching method, an inflation method, and a casting method.
Moreover, other resin and various additives can be mixed with a base material sheet as needed for the purpose of improvement, such as handling property, durability, and light reflectivity, or economical efficiency. Examples of the additive include an antioxidant, an ultraviolet absorber, a weathering stabilizer, a light diffusing agent, a nucleating agent, a pigment (for example, titanium oxide, barium sulfate, and carbon black), a flame retardant, a discoloration inhibitor, Examples include decomposition inhibitors and heat radiation agents.
Furthermore, on the surface and / or the back surface of the base sheet, embossing, various treatments (corona treatment, plasma treatment, etc.) and coating (fluorine) are performed as necessary in order to improve handling properties, adhesiveness and durability. Resin coating, hydrolysis prevention coating, hard coating, etc.).
The substrate sheet may be a single layer or a laminate composed of two or more layers.

The back protective layer (C) used in the present invention may have a structure in which a functional layer such as a barrier layer or an adhesive layer is further laminated on the base sheet, and balances the characteristics required for the back protective layer (C). In order to achieve well, it is preferable that it is a laminated structure.
The properties generally required for the back protective layer (C) include adhesion to the sealing material layer, mechanical strength, durability (weather resistance, hydrolysis resistance, etc.), light reflectivity, and water vapor barrier properties. , Flame retardancy, design properties, economy, appearance after lamination, etc. Especially in the case of crystalline silicon solar cell module, adhesion to sealing material layer, mechanical strength, durability, economy And the appearance after lamination is regarded as important.

For the back protective layer (C) used in the present invention, the following laminated structure is suitably used in order to achieve these characteristics in a balanced manner. Here, the adhesive layer to be described later is a layer mainly improving the adhesiveness between the respective layers of the back surface protective layer (C), and is not particularly limited. For example, a polyurethane adhesive or a polyester adhesive is used. An agent or a resin modified with a polar group can be preferably used. Moreover, the easy-adhesion layer to be described later is a layer mainly improving the adhesion with the sealing material layer, and is not particularly limited. For example, an ethylene-vinyl acetate copolymer or a polyethylene resin or A polypropylene resin or the like can be suitably used.
(1) Fluorine-based resin layer / adhesive layer / polyester resin layer / adhesive layer / easy-adhesive layer (encapsulant layer side); specifically, PVF / adhesive layer / biaxially stretched PET / adhesive layer / EVA, PVF / Adhesive layer / biaxially stretched PET / adhesive layer / PE, PVF / adhesive layer / biaxially stretched PET / adhesive layer / PP, ETFE / adhesive layer / biaxially stretched PET / adhesive layer / EVA, ETFE / adhesive layer / two Examples thereof include axially stretched PET / adhesive layer / PE, ETFE / adhesive layer / biaxially stretched PET / adhesive layer / PP, and the like.
(2) Polyester resin layer / adhesive layer / polyester resin layer / adhesive layer / easy-adhesive layer (encapsulant layer side); specifically, biaxially stretched PET (hydrolysis resistant formulation) / adhesive layer / biaxial stretch PET / adhesive layer / EVA, biaxially stretched PET (hydrolysis resistant formulation) / adhesive layer / biaxially stretched PET / adhesive layer / PE, biaxially stretched PET (hydrolysis resistant formulation) / adhesive layer / biaxially stretched PET / Adhesive layer / PP, (surface coating) biaxially stretched PET / adhesive layer / biaxially stretched PET / adhesive layer / easy-adhesive layer, and the like.
(3) Polyester resin layer / adhesive layer / easy-adhesive layer (encapsulant layer side); specifically, biaxially stretched PET (hydrolysis resistant formulation) / adhesive layer / EVA, biaxially stretched PET (hydrolysis resistant) Formulation) / adhesive layer / PE, biaxially stretched PET (hydrolysis resistant formulation) / adhesive layer / PP, (surface coating) biaxially stretched PET / adhesive layer / easy-adhesive layer, and the like.

  The adhesive layers (1) to (3) are arranged as necessary, and can be configured without an adhesive layer. Further, when importance is attached to the water vapor barrier property, for example, in the above-described biaxially stretched PET (hydrolysis resistant formulation) / adhesive layer / biaxially stretched PET / adhesive layer / PE configuration, Decomposition prescription) / adhesion layer / various vapor deposition layers (SiOx, alumina, etc.) / Biaxially stretched PET / adhesive layer / biaxially stretched PET / adhesive layer / PE can be used.

  The crystal melting peak temperature (Tm) of the easy adhesion layer is generally 80 ° C. or higher and 165 ° C. or lower. In the present invention, the crystal melting peak temperature (Tm) of the easy-adhesion layer is the lower limit from the viewpoints of adhesion to the sealing material layer and economics, the appearance of the solar cell module, the heat resistance of the easy-adhesion layer itself, and the like. Is preferably 95 ° C, more preferably 100 ° C. On the other hand, the upper limit is preferably 140 ° C, more preferably 125 ° C.

  The total thickness of the back surface protective layer (C) used in the present invention is not particularly limited and may be appropriately selected in consideration of desired performance, but is generally 50 μm or more and 600 μm or less, preferably 150 μm or more and 400 μm. It is as follows. Further, in order to satisfy the dielectric breakdown voltage of 1 kV or more, it is preferably 200 μm or more, and more preferably 250 μm or more.

[Method for manufacturing solar cell module]
In the method for producing a solar cell module of the present invention, the laminating temperature when laminating each member is usually 100 to 170 ° C., preventing thermal deterioration of the solar cell element (cell), and the end of the solar cell module. In order to improve the partial adhesiveness, the temperature is preferably 100 to 160 ° C, more preferably 100 to 150 ° C.
In the present invention, the “laminate temperature” refers to the front protective layer (A), the encapsulant for forming the encapsulant layer (B1), the solar cell element, the encapsulant for forming the encapsulant layer (B2), And the set temperature of the laminator when the back surface protective layer (C) is laminated and laminated, that is, the temperature of the heat source in the laminator device. A laminating temperature of 100 ° C. or higher is preferable because adhesion to the front protective layer (A) and the rear protective layer (C) can be obtained. On the other hand, if it is 150 degrees C or less, while suppressing the thermal deterioration of a solar cell element and making the edge part adhesiveness of a module favorable, it is preferable. It is also effective to perform the lamination in as short a time as possible in consideration of other characteristics (for example, vacuum suction time of 3 to 10 minutes, pressurization time of 1 to 10 minutes, etc.).
In the case of using a laminator having heat sources on both sides, the temperature of a heat source having a high temperature (hereinafter sometimes referred to as “high temperature heat source”) is not particularly limited, but is usually 100. It is about -170 degreeC, Preferably it is 100-160 degreeC, More preferably, it is 100-150 degreeC. Further, the temperature of the heat source having a low temperature when laminating is not particularly limited as long as it is lower than the temperature of the high temperature heat source.

  As a method for producing the solar cell module of the present invention, known production methods other than the above-mentioned laminating temperature can be applied and are not particularly limited, but at least the front protective layer (A) and the sealing material layer (B1) are formed. Sealing layer, solar cell element, sealing material layer (B2) forming sealing material, and back protective layer (C) are laminated to form a laminate, and bubbles between the layers of the laminate are removed. For this purpose, the laminate is vacuum-sucked and preheated (vacuum preheating) for 5 to 10 minutes as necessary to soften the sealing material, and then laminated (heated) under conditions of a laminating temperature of 100 to 150 ° C. and a pressure of 30 to 100 kPa. It is preferable to have a step of crimping. In addition, the pressurization time at the time of lamination is usually about 1 to 30 minutes. By applying the above manufacturing method, a solar cell module having good edge adhesion and excellent moisture resistance and durability can be obtained. Also, batch type manufacturing equipment, roll-to-roll type manufacturing equipment, and the like can be applied.

  The solar cell module of the present invention can be used in various applications regardless of indoors or outdoors, such as small solar cells represented by mobile devices and large solar cells installed on roofs and rooftops, depending on the type and module shape of the applied solar cells. Can be applied.

  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 back protective layer (back sheet), the sealing material, and the solar cell module in this example were performed as follows.

<Measurement of density>
For the density measurement of the sealing material layer, a dry density measuring device (trade name: AccuPyc II 1340, manufactured by micromeritics) was used. About 5 g of various sealing materials were sampled using the apparatus, and the density (g / cm ³ ) was measured with He gas under a temperature condition of 23 ° C.

<Measurement of crystal melting peak temperature (Tm) and crystal melting heat (ΔHm)>
The crystal melting peak temperature (Tm) and the crystal melting heat quantity (ΔHm) of the sealing material layer are measured using a differential scanning calorimeter (trade name: Pyris1 DSC, manufactured by Perkin Elmer Co., Ltd.) in accordance with JIS K7121. did. About 10 mg of the sample was heated from −40 ° C. to 200 ° C. at a heating rate of 10 ° C./min, heated, held at 200 ° C. for 5 minutes, then cooled to −40 ° C. at a cooling rate of 10 ° C./min, The temperature was raised to 200 ° C. at a heating rate of 10 ° C./min. From the obtained thermogram, the crystal melting peak temperature (Tm), the crystal melting heat quantity (ΔHm), and the crystal melting heat quantity (ΔHm (≧ 100 ° C.)) of 100 ° C. or more (J / g) were determined.

<Measurement of water vapor transmission rate>
The water vapor transmission rate of the encapsulant layer was measured using a water vapor transmission rate measuring device (manufactured by MOCON, trade name: PERMATRAN-W) at a temperature of 40 ° C. and RH 90% for 24 hours. The water vapor transmission rate per 100 μm thickness was calculated.

<Measurement of elastic modulus>
The storage elastic modulus (E ′) at 20 ° C. of the sealing material layer was measured using a dynamic viscoelasticity measuring device (product name: Viscoelastic Spectrometer DVA-200, manufactured by IT Measurement Co., Ltd.) at a measurement frequency of 10 Hz, The measurement temperature was −50 ° C. to 150 ° C., the strain was 0.1%, the distance between chucks was 25 mm, the heating rate was 3 ° C./min, and the tensile mode was measured in the TD direction.

<Measurement of MFR>
The MFR (g / 10 minutes) of each resin constituting the sealing material layer and the sealing material layer was measured under the conditions of temperature: 190 ° C. and load: 21.18 N in accordance with JIS K7210.

<Measurement of gel fraction>
The gel fraction of the encapsulant layer was determined by measuring the mass% of xylene-insoluble matter after Soxhlet extraction of various encapsulants at the boiling point of xylene based on ASTM-2765-95.

<Measurement of end peel amount>
As shown in FIG. 3, 10 mm produced from a back protective layer member (back sheet) at one of the four corners on the back protective layer 16 side of the module 100 before cutting (trimming) produced in the examples and comparative examples. A handle (30 in FIG. 3) of width × 75 mm length was attached and left at room temperature (25 ° C.) for 1 day. Then, the module is taken out, a pull gauge is attached to the handle, a 180 ° peel test is performed with each load of 30 kgf and 100 kgf, and the maximum peel amount (initial peel amount) from the end of the module is Measured using a scale.
Also, after the sample tested with a load of 100 kgf was left for 1000 hours under the conditions of a temperature of 85 ° C. and 85% RH (dump heat (DH) test), a 180 ° peel test was performed again with a load of 100 kgf, and the module end The maximum peel amount from the part (the end peel amount after DH) was measured using a metal scale.
Furthermore, the measurement result of the initial edge peeling amount was evaluated according to the following criteria.
A: Initial edge peeling amount is 1 mm or less at a load of 30 kgf and less than 7 mm at a load of 100 kgf. ○: Initial edge peeling amount is 1 mm or less at a load of 30 kgf and 7 mm or more and less than 9 mm at a load of 100 kgf. The amount is 1 mm or less at a load of 30 kgf and 9 mm or more at a load of 100 kgf. X: The initial end peeling amount exceeds 1 mm at a load of 30 kgf.

<Diagonal length ratio>
The diagonal length ratio x1 / x2 (see FIG. 2) of the module 100 manufactured in the example and the comparative example is the sealing in the contact region between the sealing material layer (B2) and the front protective layer (A) after trimming. It calculated from the diagonal length x1 of a material layer (B2) and the diagonal length x2 of a module. The value calculated from the average value of the two diagonal lengths was used as the value of x1, and the average value of the measured values at all corners.

<Adhesion evaluation>
As shown in FIG. 4A, using the embossed glass, the sealing material, the back sheet and the release film used in each example and comparative example, the embossed glass 101 / release film 401 / sealing material 121A / After laminating the sealing material 121B / back sheet 161 in this order, the laminate 200 was produced by laminating under the conditions of the respective examples and comparative examples (FIG. 4B). FIG. 4B is a schematic cross-sectional view of the laminate 200. Next, the release film 401 was removed from the laminate 200 in FIG. 4B to obtain a laminate 300 (FIG. 4C). In the laminate 300, the end of the encapsulant 121A / encapsulant 121B / backsheet 161 on the side from which the release film 401 is removed is Z, and as shown in FIG. Cuts were made at intervals to cut the sealing material 121A / sealing material 121B / backsheet 161 (broken line portion in FIG. 4D), and five test samples 501 having a width of 10 mm were produced. The test sample 501 is in a state of being adhered to the embossed glass 101 in a range where the distance from the end on the opposite side of Z is 70 mm ± 10 mm. A peel test (180 ° peel, test speed 50 mm / min) was performed using a universal tensile tester (manufactured by Intesco, model: 200X) so that the end Z of the test sample 501 could be gripped. The maximum value (maximum adhesive strength) was read in the peel test chart, and the adhesion between the embossed glass and the sealing material was evaluated according to the following criteria.
(Adhesion evaluation criteria)
○: Maximum adhesive strength is 60 N / 10 mm width or more ×: Maximum adhesive strength is less than 60 N / 10 mm width

<Appearance after lamination>
The appearance evaluation of the modules produced in the examples and comparative examples was evaluated according to the following criteria.
○: No cell cracks or irregularities on the back protective layer side surface ×: Cell cracks or irregularities on the back protective layer side surface occur

<Measurement of total light transmittance>
The total light transmittance of the encapsulant layer was determined by sanding the encapsulant with 2 mm thick optical glass (manufactured by SCHOTT, borosilicate glass, trade name: Tempax), and then using a haze meter (Nippon Denshoku Industries Co., Ltd.) ), Product name: NDH-5000), and measured according to JIS K7105. The front side transparency of the solar cell module was evaluated according to the following criteria.
○: Total light transmittance of the sealing material layer (B1) is 85% or more ×: Total light transmittance of the sealing material layer (B1) is less than 85%

<Preparation of sealing material 1>
The sealing material 1 has a two-type three-layer configuration in which (I) layer / (II) layer / (I) layer are laminated in this order. The resin composition (C-1) having the composition shown in Table 1 is used as the (I) layer, and the resin composition (C-2) having the composition shown in Table 1 is used as the (II) layer. After co-extrusion molding at a resin temperature of 180 to 200 ° C. by a T-die method using a same-direction twin screw extruder so as to be laminated in the order of layer / (II) layer / (I) layer, The film was rapidly cooled with a cast embossing roll to obtain a sealing material 1 ((I) layer / (II) layer / (I) layer = 45 μm / 360 μm / 45 μm) having a total thickness of 450 μm.

<Preparation of sealing material 2>
The sealing material 2 has a two-kind three-layer structure in which (I) layer / (II) layer / (I) layer are laminated in this order. The resin composition (C-3) having the composition shown in Table 1 is used as the (I) layer, and the resin composition (C-4) having the composition shown in Table 1 is used as the (II) layer. After co-extrusion molding at a resin temperature of 180 to 200 ° C. by a T-die method using a same-direction twin screw extruder so as to be laminated in the order of layer / (II) layer / (I) layer, The film was rapidly cooled with a cast embossing roll to obtain a sealing material 2 ((I) layer / (II) layer / (I) layer = 45 μm / 360 μm / 45 μm) having a total thickness of 450 μm.

<Preparation of sealing material 3>
The sealing material 3 has a two-kind three-layer structure in which (I) layer / (II) layer / (I) layer are laminated in this order. The resin composition (C-5) having the composition shown in Table 1 is used as the (I) layer, and the resin composition (C-6) having the composition shown in Table 1 is used as the (II) layer. After co-extrusion molding at a resin temperature of 180 to 200 ° C. by a T-die method using a same-direction twin screw extruder so as to be laminated in the order of layer / (II) layer / (I) layer, The film was rapidly cooled with a cast embossing roll to obtain a sealing material 3 ((I) layer / (II) layer / (I) layer = 45 μm / 360 μm / 45 μm) having a total thickness of 450 μm.

Details of the resin components shown in Table 1 are shown below.
PE-1: ethylene-octene random copolymer (manufactured by Mitsui Chemicals, Inc., trade name: Tafmer H5030S, MFR: 5 g / 10 min, Tm: 59 ° C., ΔHm: 56 J / g, ΔHm (≧ 100 ° C.): 0J / g
PE-2: ethylene-octene block copolymer (manufactured by Dow Chemical Co., Ltd., trade name: Infuse 9100, MFR: 0.5 g / 10 min, Tm: 119 ° C., ΔHm: 45 J / g, ΔHm (≧ 100 ° C.): 41 J / g)
PE-3: ethylene-octene random copolymer (manufactured by Prime Polymer Co., Ltd., trade name: Evolue P9018, MFR: 1 g / 10 min, Tm: 88 ° C., ΔHm: 65 J / g, ΔHm (≧ 100 ° C.): 2J / g)
PE-4: General-purpose LLDPE (manufactured by Prime Polymer Co., Ltd., trade name: NEOZEX 0234N, MFR: 2 g / 10 min, Tm: 118 ° C., ΔHm: 122 J / g, ΔHm (≧ 100 ° C.): 66 J / g)
SiR-1: Silane-modified polyethylene copolymer (manufactured by Mitsubishi Chemical Corporation, trade name: Linkron SL800N, MFR: 1.5 g / 10 min, Tm: 54 ° C. and 116 ° C., ΔHm: 45 J / g, ΔHm (≧ 100 ° C.): 5 J / g)
SiR-2: Silane-modified polyethylene copolymer (Mitsubishi Chemical Corporation, trade name: Linkron XLE815N, MFR: 0.5 g / 10 min, Tm: 122 ° C., ΔHm: 22 J / g, ΔHm (≧ 100 ° C): 106 J / g)

<Example 1>
150 mm x 150 mm embossed glass (Asahi Glass Co., Ltd., trade name: Solite, thickness: 3.2 mm) is used for the front protective layer (A), and 140 mm x 140 mm is used for the sealing material layer (B1). The sealing material 1 is a solar cell element, a crystalline silicon cell (Q-cells Japan, 5-inch cell), the sealing material layer (B2) is a sealing material 2 cut to 160 mm × 153 mm, and a back protective layer ( For C), a 172 mm × 170 mm back sheet (polyolefin / PET / PVF laminate sheet, manufactured by TAIFLEX, trade name: Solmate VTPE1, thickness: 380 μm) was used. After laminating in the order of embossed glass / sealing material 1 / cell / sealing material 2 / back sheet with the center of each member aligned, vacuum preheating at 145 ° C. for 5 minutes, pressure for 10 minutes, pressure of 50 kPa Vacuum lamination was performed according to conditions, and a member protruding from the embossed glass was trimmed to obtain a solar cell module. Various evaluation results in this module are shown in Table 2.

<Example 2>
A solar cell module was obtained in the same manner as in Example 1 except that the sealing material 1 cut to 130 mm × 130 mm was used for the sealing material layer (B1). Various evaluation results in this module are shown in Table 2.

<Example 3>
A solar cell module was obtained in the same manner as in Example 1 except that the sealing material 1 cut to 145 mm × 145 mm was used for the sealing material layer (B1). Various evaluation results in this module are shown in Table 2.

<Example 4>
Except for using the sealing material 1 obtained by cutting the sealing material layer (B1) into 160 mm × 153 mm and then cutting out a right isosceles triangle having a side of 20 mm from the four corners of the sheet as shown in FIG. Obtained the solar cell module by the same method as Example 1. Various evaluation results in this module are shown in Table 2.

<Example 5>
150 mm x 150 mm embossed glass (Asahi Glass Co., Ltd., trade name: Solite, thickness: 3.2 mm) is used for the front protective layer (A), and 140 mm x 140 mm is used for the sealing material layer (B1). The sealing material 1 is a solar cell element, a crystalline silicon cell (5-inch cell, manufactured by Q Cells Japan), and an EVA-based sealing material (Mitsui Chemicals East Cello ( Ltd.), trade name: sOLAR EVA, water vapor transmission rate (thickness 100μm ^{terms): 149g / m 2 / 24hr} ) and back protective layer (C) in the 172 mm × 170 mm backsheet (TAIFLEX Co., trade name: Solmate VTPE1) was used. After laminating the embossed glass / sealing material 1 / cell / EVA / back sheet in this order, vacuum lamination was performed at 150 ° C. under conditions of vacuum preheating for 5 minutes, pressurization for 15 minutes, and pressure of 50 kPa, and the part protruding from the embossed glass was trimmed. Thus, a solar cell module was obtained. Various evaluation results in this module are shown in Table 2.

<Comparative Example 1>
A solar cell module was obtained in the same manner as in Example 1 except that the sealing material 1 cut to 160 mm × 153 mm was used for the sealing material layer (B1). Various evaluation results in this module are shown in Table 2.

<Comparative Example 2>
A solar cell module was obtained in the same manner as in Example 2 except that the sealing material 1 cut to 160 mm × 153 mm was used for the sealing material layer (B2). Various evaluation results in this module are shown in Table 2.

<Comparative Example 3>
Example 1 except that the sealing material 1 cut to 150 mm × 150 mm was used for the sealing material layer (B1), and the sealing material 2 cut to 150 mm × 150 mm was used for the sealing material layer (B2). A solar cell module was obtained in the same manner. Various evaluation results in this module are shown in Table 2.

<Comparative example 4>
Example 1 except that the sealing material 1 cut to 160 mm × 153 mm was used for the sealing material layer (B1) and the sealing material 2 cut to 140 mm × 140 mm was used for the sealing material layer (B2). A solar cell module was obtained in the same manner. Various evaluation results in this module are shown in Table 2.

<Comparative Example 5>
Example 1 except that the sealing material 3 cut to 140 mm × 140 mm was used for the sealing material layer (B1) and the sealing material 2 cut to 160 mm × 153 mm was used for the sealing material layer (B2). A solar cell module was obtained in the same manner. Various evaluation results in this module are shown in Table 2.

  From the results in Table 2, the solar cell modules (Examples 1 to 5) of the present invention have a small end peel amount even after the initial and dump heat tests, and the front protective layer (A) and the back protective layer (C), End part adhesiveness with a sealing material layer is favorable. Therefore, it is possible to realize a solar cell module that is unlikely to cause a decrease in power generation efficiency due to moisture absorption and that has excellent long-term durability. Furthermore, in the solar cell module (Examples 1 to 4) using the sealing material having a high water vapor barrier property, there is almost no decrease in end adhesion after the dump heat test, and the result is particularly excellent in heat resistance and moisture resistance. It was. Moreover, the solar cell module of this invention is excellent also in transparency of the front side (solar light receiving side). On the other hand, in the solar cell modules of Comparative Examples 1, 3, and 4 that do not satisfy the requirements of the present invention, since the sealing material layer (B2) does not have a contact point with the front protective layer (A), the end peeling amount is large. As a result. In the solar cell module of Comparative Example 2, since the same sealing material is used for the sealing material layer (B1) and the sealing material layer (B2), the density is the same and the end peeling amount is large. It was. In the solar cell module of Comparative Example 5, the density of the sealing material layer (B1) was higher than that of the sealing material layer (B2), resulting in poor appearance after lamination and transparency on the front side.

  According to the present invention, a solar cell module that has good edge adhesion even after exposure to high temperature and high humidity for a long time, excellent moisture resistance and durability, and excellent transparency on the front side (sunlight receiving side). Can provide. The solar cell module of the present invention can be used in various applications regardless of indoors or outdoors, such as small solar cells represented by mobile devices and large solar cells installed on roofs and rooftops, depending on the type and module shape of the applied solar cells. Can be applied.

10 ... Front protective layer (A)
12A ・ ・ Encapsulant layer (B1)
12B ・ ・ Encapsulant layer (B2)
14 ... solar cell element 16 ... back protective layer (C)
20 ... Wiring 30 ... Handle 100 ... Solar cell module 101 ... Embossed glass 121A, 121B ... Sealing material 161 ... Back sheet 200, 300 ... Laminated body 401 ... Release film 501 ...・ Test sample for adhesion evaluation

Claims (1)

  A solar cell module having a front protective layer (A), a sealing material layer (B1), a solar cell element, a sealing material layer (B2), and a back protective layer (C) in this order, the front protective layer (A ) Is in contact with a part of the sealing material layer (B2), and the density of the sealing material layer (B1) is lower than the density of the sealing material layer (B2).