JP2016072560A - Sealant for solar battery and solar battery module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sealant for a solar battery, which enables the suppression of the worsening of adhesion owing to the aging after manufacturing.SOLUTION: A sealant for a solar battery comprises a composition including an ethylene/α-olefin copolymer, an organic peroxide, a silane coupling agent including an epoxy group, and a silane coupling agent including a (meth)acryloyl group. Supposing that the content of the silane coupling agent including an epoxy group to 100 pts.mass of the ethylene/α-olefin copolymer is W(SC(A)) in units of pt.mass, and the content of the silane coupling agent including a (meth)acryloyl group to 100 pts.mass of the ethylene/α-olefin copolymer is W(SC(B)), the content of the silane coupling agent in the composition satisfies the following formulas: (Formula 1) and (Formula 2): 0.1<W(SC(B)) (Formula 1); and 0.8<W(SC(A))/W(SC(B))<3 (Formula 2).SELECTED DRAWING: Figure 1

Description

  The present invention relates to a solar cell encapsulant using an ethylene / α-olefin copolymer, and in particular, a solar cell encapsulant excellent in shelf life with little decrease in adhesion over time after the production of the encapsulant, And a technique suitable for a solar cell module using the same.

In recent years, solar cells have attracted attention as a clean power generation technology that uses sunlight. A typical solar cell configuration is illustrated in FIG.
In the solar cell module 101 shown in FIG. 3, a plurality of silicon cells in which a negative electrode 103 is provided on a light receiving surface (front surface) 102a of a silicon substrate 102 and a positive electrode 104 is provided on a surface (back surface) 102b opposite to the light receiving surface. 105, the light receiving surface side sealing material 109a and the back surface between the transparent base material 107 on the light incident side and the back side insulating base material 108 in a state where adjacent silicon cells 105 are connected in series by the wiring member 106. It is a structure sealed with the side sealing material 109b.

Since this solar cell module 101 has a current collecting wiring (bus bar) formed on the light receiving surface side of the silicon cell, it does not receive light under the bus bar and does not contribute to power generation. On the other hand, a back contact type solar cell that collects current with a circuit board provided on the back side of the silicon cell has been developed (see, for example, Patent Document 1).
The role of the sealing material used in the solar cell module is to protect a power generation portion composed of silicon cells, wiring members, and the like from an external environment such as impact, wind and rain, and light. Therefore, it is important that the sealing material itself has a small adverse effect on the power generation portion due to a chemical reaction or the like. In addition, it is important that the sealing material has strong adhesion to the adjacent member because moisture or the like enters the interface from the adjacent member such as the power generation portion to adversely affect the power generation member.

As a sealing material for the solar cell module, conventionally, an ethylene / vinyl acetate copolymer (EVA) blended with an organic peroxide to give crosslinkability is used to impart mechanical strength and durability. Therefore, a crosslinking aid, a light stabilizer, an ultraviolet absorber, and the like, and silane coupling are added to impart adhesion (for example, Patent Document 2).
Since the ethylene / vinyl acetate copolymer (EVA) resin has a hydrolyzable ester structure, deterioration such as yellowing and foaming is remarkable due to the influence of moisture and heat in long-term use. There is concern that the electrode member is corroded by acetic acid generated by the reaction, and the power generation performance is lowered.

On the other hand, a sealing material for a solar cell in which an amorphous or low crystalline ethylene / α-olefin copolymer is blended with an organic peroxide has been proposed (for example, patent document). 3).
However, a sealing material using an ethylene / α-olefin copolymer has a remarkable decrease in adhesion with time after manufacturing the sealing material, as compared with EVA, and has a problem in shelf life. In the ethylene / α-olefin copolymer, it is considered that a change with time of the silane coupling agent is more likely to occur than EVA, which is a factor of lowering the adhesion. For this reason, the quality guarantee period after manufacture is short and a concern arises about the reliability of a solar cell module.

JP 2005-11869 A Japanese Patent No. 3323560 Japanese Patent No. 5119142

  An object of the present invention is to provide a sealing material for a solar cell in which a shelf life is improved by suppressing a decrease in adhesion over time after manufacturing the sealing material in a sealing material using an ethylene / α-olefin copolymer, and It is an object to provide a solar cell module using the same.

As a result of intensive studies to solve the above problems, the present inventors have found that the use of a specific silane coupling agent in combination suppresses the decrease in adhesion over time after the production of the sealing material. Invented.
That is, the solar cell sealing material of one embodiment of the present invention includes an ethylene / α-olefin copolymer, an organic peroxide, a silane coupling agent containing an epoxy group, and a silane containing a (meth) acryloyl group. A composition containing a coupling agent, wherein the mass part of the silane coupling agent containing an epoxy group with respect to 100 parts by mass of the ethylene / α-olefin copolymer is W (SC (A)), and the ethylene / α-olefin copolymer. When the silane coupling agent containing a (meth) acryloyl group with respect to 100 parts by mass of the polymer is W (SC (B)), the content of the silane coupling agent in the composition is the following (formula 1) and (Equation 2) is satisfied.
0.1 <W (SC (B)) (Formula 1)
0.8 <W (SC (A)) / W (SC (B)) <3 (Formula 2)

  The sealing material for solar cells of the present invention contains an ethylene / α-olefin copolymer, an organic peroxide, and a specific silane coupling agent, and suppresses a decrease in adhesion over time after manufacturing the sealing material. For this reason, the solar cell module using the sealing material of the present invention can be expected to improve reliability (output stability in long-term outdoor use).

It is a typical longitudinal cross-sectional view which shows the principal part of a back contact type solar cell module. It is a typical longitudinal cross-sectional view which shows the sample structure for measuring the adhesive force of a sealing material and a to-be-adhered body. It is a typical longitudinal cross-sectional view which shows the principal part of a common solar cell module.

Next, embodiments according to the present invention will be described with reference to the drawings.
A configuration example of the back contact solar cell of this embodiment is illustrated in FIG. In the back contact type solar cell module 201, a positive electrode 203 and a negative electrode 204 are formed on a surface (back surface) 202b opposite to the light receiving surface (front surface) 202a of the silicon substrate 202. A plurality of such silicon cells 205 are disposed between the transparent substrate 206 on the light incident side and the circuit substrate 210 in which the metal foil 208 having a predetermined circuit pattern is provided on the insulating substrate 207 via the adhesive layer 209. Are arranged at intervals.

  Further, the space between the light incident side transparent base material 206 and the light receiving surface 202a of the silicon substrate 202 is sealed with a light receiving surface side sealing material 211a, and the back surface 202b of the silicon substrate 202 and the circuit board 210 are sealed. The space is sealed with the back surface side sealing material 211b. The positive electrode 203 and the negative electrode 204 and the metal foil 208 are electrically connected by a conductive connection member 212 such as solder penetrating the back surface side sealing material 211b. That is, a through hole 213 penetrating in the thickness direction is formed at a position corresponding to each electrode 203, 204 in the back surface side sealing material 211b, and the through hole 213 is filled with a conductive connection member 212 such as low melting point solder. Thus, the electrodes 203 and 204 and the metal foil 208 are electrically connected via the conductive connection member 212.

The solar cell encapsulants 211a and 211b of this embodiment include an ethylene / α-olefin copolymer, an organic peroxide, a silane coupling agent containing an epoxy group, and a silane coupling containing a (meth) acryloyl group. It is a composition containing an agent.
Since the ethylene / α-olefin copolymer has a short branched structure of α-olefin in the molecule, it is generally characterized by low density and high transparency. Furthermore, the mechanical properties such as flexibility and fluidity can be controlled widely depending on the type of α-olefin and the manufacturing process, and characteristics suitable for the solar cell encapsulants 211a and 211b can be imparted. Is possible.

As the ethylene / α-olefin copolymer of the present embodiment, for example, Prime Polymer Co., Ltd. or various grades marketed by Nippon Polyethylene Co., Ltd. can be used. Linear low density polyethylene (LLDPE) is preferable from the viewpoints of properties and processability such as melting point and melt flow rate.
The melt flow rate (MFR: 190 ° C., 21.18 N load) of the linear low density polyethylene (LLDPE) is preferably 0.1 to 50 g / 10 minutes, more preferably 1 to 35 g / 10 minutes. If the MFR is less than 0.1 g / 10 min, the fluidity is too small and processing is difficult. On the other hand, if it is larger than 50 g / 10 minutes, the fluidity is too high and it is difficult to form a sheet. The density is preferably 0.860 to 0.920 g / cm ³ , and more preferably 0.87 to 0.90 g / cm ³ . A material smaller than 0.860 g / cm ³ has a melting point that is too low, so that a blocking problem is likely to occur when the sheet is wound during processing. Moreover, since the melting point of a material larger than 0.920 g / cm ³ is too high, the organic peroxide is decomposed at the sheet processing temperature, causing problems such as gel generation.

MFR is defined in JIS K7210: 1999.
The organic peroxide is not particularly limited. For example, 1,1-di (t-butylperoxy) cyclohexane, 1,1-di (t-hexylperoxy) cyclohexane, n-butyl-4, 4-di- (t-butylperoxy) valerate, t-butylperoxy-3,5,5-trimethylhexanoate, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, It is possible to use t-butylcumyl peroxide, 2,2-di- (t-butylperoxy) butane. These organic peroxides may be used alone or in combination of two or more.

In addition to the organic peroxide, the solar cell encapsulants 211a and 211b of the present embodiment may contain a crosslinking aid that promotes a crosslinking reaction. Examples of the crosslinking aid include triallyl isocyanurate, diallyl phthalate, triallyl cyanurate and the like.
In this embodiment, a silane coupling agent containing an epoxy group and a silane coupling agent containing a (meth) acryloyl group are used in combination, and the content in the encapsulant composition is expressed by the following relational expressions (formula 1) (formula 2) Meet.

0.1 <W (SC (B)) (Formula 1)
0.8 <W (SC (A)) / W (SC (B)) <3 (Formula 2)
here,
SC (A): Silane coupling agent containing an epoxy group SC (B): Silane coupling agent containing a (meth) acryloyl group W (SC (A)): 100 mass of an ethylene / α-olefin copolymer Parts by mass of SC (A) with respect to parts. W (SC (B)): parts by mass of SC (B) with respect to 100 parts by mass of the ethylene / α-olefin copolymer.

  The silane coupling agent containing an epoxy group is not particularly limited, and 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyl Examples include trimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 3-glycidoxypropyltriethoxysilane.

  The silane coupling agent containing a (meth) acryloyl group is not particularly limited, and 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, Examples include 3-methacryloxypropyltriethoxysilane and 3-acryloxypropyltrimethoxysilane.

  In the sealing materials 211a and 211b of this embodiment, a silane coupling agent having a (meth) acryloyl group is introduced into the resin skeleton by graft polymerization of the functional group at the time of cross-linking, and one end of adhesion with an adherend. Is responsible. When the required minimum amount of the silane coupling agent is present and W (SC (B)) is 0.1 or less in (Formula 1), an adherend such as glass or metal is produced immediately after the production of the sealing material. Adhesiveness with is not sufficiently obtained.

  The ethylene / α-olefin copolymer, which is a resin component of the sealing materials 211a and 211b of the present embodiment, is likely to cause segregation of the silane coupling agent, and is considered to be a factor that deteriorates the adhesiveness over time. When segregation occurs, the local concentration of the silane coupling agent increases, so that the hydrolysis and dehydration condensation reactions of the alkoxy group of the silane coupling agent are likely to occur, and the alkoxy group responsible for adhesion with the (meth) acryloxy group described above Since it is lost, it is thought that it leads to the fall of adhesiveness.

  The sealing materials 211a and 211b of the present embodiment can suppress a decrease in the adhesion of the sealing materials 211a and 211b over time by using the silane coupling agents in combination. Chemical species produced by condensation of a silane coupling agent having an epoxy group and a methacrylic group having a (meth) acryloxy group at the time of storage of an encapsulant have an epoxy group at the end that has excellent affinity for metals and glass Therefore, it is expected that even if condensation occurs, the effect of lowering the adhesion is small.

Content of each silane coupling agent of this embodiment satisfy | fills the relationship of (Formula 2). In (Formula 2), when W (SC (A)) / W (SC (B)) is 0.8 or less, or 3 or more, the amount of decrease in adhesion over time increases, and the sealing material is stored. Subsequent adhesion cannot be obtained sufficiently.
Moreover, content of each silane coupling agent is 1.0 mass by the sum total (W (SC (A)) + W (SC (B))) of both with respect to 100 mass parts of ethylene / alpha-olefin copolymers. It is preferable that the part is less. When the total amount of the silane coupling agent exceeds 1.0 part by mass, the deterioration of the adhesiveness with time increases. Since the deposition of the sealing material surface of the silane coupling agent is increased, it is considered that the adhesion between the adherend and the sealing materials 211a and 211b is hindered by the deposited silane coupling agent.

Sufficient adhesion assumed here means that the peel strength from the adherend is 40 N / in the adhesion measurement described in the examples described later during storage for 100 days in the room temperature environment after the production of the sealing material. It means not less than cm. If the peel strength is lower than this value, the long-term reliability of the solar cell module is affected, and there is a concern about a decrease in power generation efficiency or failure.
The solar cell encapsulants 211a and 211b of the present embodiment may contain a carbon dioxide carbonate ion scavenger in order to suppress corrosion of the metal part of the module constituent member due to carbonate ions. Carbon dioxide carbonate ion scavenger chemically captures carbon dioxide and carbonate ions generated by the thermal decomposition of organic peroxide in modularization (for example, chemical reaction) or physically captures ( For example). As the metal corrosion caused by carbon dioxide, for example, the following reaction is known in which copper and carbon dioxide react with each other in a high-temperature and humid atmosphere to produce basic copper carbonate.

2Cu + CO ₂ + O ₂ + H ₂ O → CuCO ₃ .Cu (OH) ₂
As carbon dioxide carbonate ion scavengers, magnesium oxide (MgO), calcium oxide (CaO), calcium hydroxide (Ca (OH) ₂ ), magnesium hydroxide (Mg (OH) ₂ ), barium hydroxide (Ba (OH) ₂ ), calcium carbonate (CaCO ₃ ), barium carbonate (BaCO ₃ ) and the like can be used, but it is preferable to use magnesium hydroxide or magnesium oxide having high transparency.

The addition amount of the carbon dioxide carbonate ion scavenger is not particularly limited, and is appropriately optimized depending on the carbon dioxide carbonate scavenger and the material of the adherend, and is generally 100 masses of ethylene / α-olefin copolymer. 0.01 parts by mass or more and 1.0 part by mass or less with respect to parts.
In the solar cell module, the solar cell encapsulants 211a and 211b of the present embodiment contain an ultraviolet absorber, an antioxidant, a light stabilizer and the like in order to improve the durability of the encapsulants 211a and 211b. May be.

As the ultraviolet absorber, for example, benzophenone-based, benzotriazole-based, triazine-based ultraviolet absorber can be used, but when using the carbon dioxide carbonate ion scavenger, the reactivity with the scavenger is small, It is preferable to use a benzotriazole-based or triazine-based ultraviolet absorber that is less affected by coloring due to the reaction product.
Examples of the benzophenone ultraviolet absorber include 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone, 2,2 ′. -Dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone, bis (2-methoxy-4-hydroxy-5-benzophenone) Methane is mentioned.

  Examples of the benzotriazole ultraviolet absorber include hydroxyphenyl-substituted benzotriazole compounds such as 2- (2-hydroxy-5-methylphenyl) benzotriazole and 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, 2- (2H-benzotriazol-2-yl) -4,6-bis (1-methyl-1- Eniruechiru) such as phenol, 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, And 2- (4,6-diphenyl-1,3,5-triazin-2-yl) -5- (hexyloxy) phenol.
Examples of the antioxidant include 1,6-hexanediol-bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], pentaerythrityl-tetrakis [3- (3 , 5-di-t-butyl-4-hydroxyphenyl) propionate], tris (2,4-di-t-butylphenyl) phosphite, 2,4-bis- (n-octylthio) -6- (4- Hydroxy-3,5-di-t-butylanilino) -1,3,5-triazine, octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate and the like.

Examples of the light stabilizer include bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate and bis (1-octyloxy-2,2,6,6-tetramethyl-4-piperidyl). ) Sebacate, bis (1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate and the like.
Here, the sealing material for solar cells according to the present invention can also be applied to a normal solar cell module (a module other than the back contact type solar cell module) as shown in FIG. When used as the back surface sealing material 211b of the back contact solar cell module as shown in FIG. 1, it is preferable to further include an insulating filler.

The back contact solar cell needs to insulate the circuit board from the cell back surface. At this time, since the insulating filler contained in the back surface sealing material 211b functions as a spacer, a short circuit due to contact between the circuit substrate and the back surface of the cell can be suppressed. As an example in which a short circuit occurs, there is a case where foreign matter is present in the laminator at the time of module production.
The insulating filler preferably has an average particle size of 10 μm or more and 200 μm or less. If the average particle diameter is smaller than 10 μm, it may not function as a spacer and insulation may not be ensured. If the average particle diameter is larger than 200 μm, it cannot be uniformly dispersed in the sealing material, resulting in low adhesion. There is a possibility.

Moreover, the compounding amount of the insulating filler is preferably 1.0 part by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the ethylene / α-olefin copolymer. If it is less than 1.0 part by mass, it does not function as a spacer, and if it exceeds 50 parts by mass, the adhesion with the back side substrate and mechanical properties may be reduced.
The insulating filler is preferably an organic filler. If an inorganic filler is used, the inside of the processing machine may be shaved during extrusion molding. Although it does not specifically limit as an organic type filler, For example, materials, such as a polymethylmethacrylate and a polystyrene, can be used.

The method for producing a solar cell encapsulant according to the present invention is not particularly limited, and a composition containing a resin and various additives is pressed into a sheet in a molten state by an extrusion molding apparatus such as a T-die. It can be manufactured by winding in a roll after being cooled.
When performing roll-shaped winding, embossing may be performed to prevent blocking. For example, the surface of the heat-melted resin sheet is brought into intimate contact with a roll having a concavo-convex pattern, thereby embossing to transfer the concavo-convex pattern of the roll to one or both sides of the resin sheet.

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples based on the present invention.
First, materials used in the examples and comparative examples are shown below.
"Ethylene / α-olefin copolymer"
・ Nippon Polyethylene Kernel KJ640T
(MFR: 30 g / 10 min, density: 0.880 g / cm ³ , melting point: 58 ° C.)
"Silane coupling agent"
・ Epoxysilane coupling agent: γ-glycidoxypropyltrimethoxysilane ・ Methacryloxysilane coupling agent: γ-methacryloxypropyltrimethoxysilane

"Additive"
Organic peroxide: 1,1-di (t-butylperoxy) cyclohexane / t-butylperoxy-2-ethylhexyl monocarbonate 100/60 mixture (mass ratio)
Crosslinking aid: triallyl isocyanurate UV absorber: 2-hydroxy-4-n-octyloxybenzophenone Light stabilizer: bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate Insulating filler: Acrylic beads (average particle size 50 μm)
Carbon dioxide carbonate ion scavenger: Magnesium oxide (average particle size 1.1 μm)

[Example 1]
With respect to 100 parts by mass of the ethylene / α-olefin copolymer, 1.6 parts by mass of the aforementioned organic peroxide, 1.0 part by mass of the crosslinking aid, 0.8 part by mass of the ultraviolet absorber, and light stabilization 0.2 parts by weight of the agent, 0.1 parts by weight of the carbon dioxide scavenger, 3.0 parts by weight of the insulating filler, 0.35 parts by weight of the epoxy silane coupling agent, and methacryloxysilane coupling agent Using the blended composition, 0.15 parts by mass, a solar cell sealing material having a processing temperature of 90 ° C. and a thickness of 200 μm was obtained by a T-die method.

[Example 2]
The solar cell encapsulant is the same as described in Example 1 except that the addition amount of the epoxysilane coupling agent is 0.30 parts by mass and the addition amount of the methacryloxysilane coupling agent is 0.20 parts by mass. Obtained.
[Example 3]
The solar cell encapsulant was the same as described in Example 1 except that the addition amount of the epoxysilane coupling agent was 0.25 parts by mass and the addition amount of the methacryloxysilane coupling agent was 0.25 parts by mass. Obtained.

[Comparative Example 1]
The solar cell encapsulant is the same as described in Example 1 except that the addition amount of the epoxysilane coupling agent is 0.4 parts by mass and the addition amount of the methacryloxysilane coupling agent is 0.1 parts by mass. Obtained.
[Comparative Example 2]
The solar cell encapsulant was the same as described in Example 1 except that the addition amount of the epoxysilane coupling agent was 0.2 parts by mass and the addition amount of the methacryloxysilane coupling agent was 0.3 parts by mass. Obtained.

[Comparative Example 3]
The solar cell encapsulant is the same as described in Example 1 except that the addition amount of the epoxysilane coupling agent is 0.45 parts by mass and the addition amount of the methacryloxysilane coupling agent is 0.05 parts by mass. Obtained.
[Comparative Example 4]
The solar cell encapsulant was the same as described in Example 1 except that the addition amount of the epoxy silane coupling agent was 0.05 parts by mass and the addition amount of the methacryloxysilane coupling agent was 0.05 parts by mass. Obtained.

[Comparative Example 5]
The solar cell encapsulant was the same as described in Example 1 except that the addition amount of the epoxysilane coupling agent was 0.75 parts by mass and the addition amount of the methacryloxysilane coupling agent was 0.50 parts by mass. Obtained.
[Comparative Example 6]
The solar cell encapsulant is the same as described in Example 1 except that the addition amount of the epoxysilane coupling agent is 0.50 parts by mass and the addition amount of the methacryloxysilane coupling agent is 0.75 parts by mass. Obtained.

[Comparative Example 7]
The solar cell encapsulant was the same as described in Example 1 except that the addition amount of the epoxysilane coupling agent was 1.00 parts by mass and the addition amount of the methacryloxysilane coupling agent was 0.25 parts by mass. Obtained.
About the sealing material for solar cells of each of the above Examples and Comparative Examples, the adhesion of each sealing material to the adherend was measured by the following sample configuration and measurement method. The measurement was carried out within 2 days (immediately after the production) of the sealing material, and after storage for 100 days in a room temperature environment.

"Sample composition"
The configuration of the adhesion evaluation sample 301 is as shown in FIG. That is, the EVA sheet 303 (thickness 450 μm), the sealing material measurement sample 304 (thickness 200 μm), and the copper foil 305 (thickness 35 μm) are overlapped on the tempered glass plate 302 (thickness 3 mm) and bonded with a vacuum laminator. An evaluation sample 301 was produced (vacuum time 5 minutes-atmospheric pressure pressing time 15 minutes, laminator temperature 150 ° C.). As the sealing material measurement sample 304, the solar cell sealing materials of the above-described Examples and Comparative Examples were applied.

"Measuring method"
Each sample for evaluation was cut into a 10 mm wide strip using a cutter at a depth reaching the glass plate from the copper foil side, and then the 10 mm wide copper foil portion was peeled off over a length of about 20 mm. The peeled portion was fixed to a chuck of a peel strength measuring machine (TENSILON (RTC-1250) manufactured by ORIENTEC Co., Ltd.), and the peel strength was measured by pulling at a peel angle of 180 ° and a peel speed of 300 mm / min.
Table 1 shows the adhesion measurement results of Examples and Comparative Examples together with the blending amounts of the respective silane coupling agents.

  As is clear from Table 1, the amount of the epoxy silane coupling agent (SC (A)) and the methacryloxysilane coupling agent (SC (B)) to 100 parts by mass of the ethylene / α-olefin copolymer (respectively, W (SC (A)), W (SC (B)) is W (SC (B))> 0.1 and 0.8 <W (SC (A)) / W (SC (B)) <1 In this range, it can be seen that a solar cell encapsulant having good adhesion immediately after the production of the encapsulant and suppressing deterioration of the adhesion over time after production of the encapsulant is obtained. A solar cell module using a battery sealing material is expected to be excellent in reliability because of a small decrease in adhesion over time in storage after manufacturing the sealing material.

201 Back contact solar cell module 202 Silicon substrate 202a Silicon substrate light receiving surface 202b Silicon substrate light receiving surface opposite surface 203 Positive electrode 204 Negative electrode 205 Silicon cell 206 Light incident side transparent substrate 207 Insulating substrate 208 Metal foil 209 Adhesive layer 210 Circuit board 211a Light-receiving surface side sealing material 211b Back surface side sealing material 212 Conductive connection member 213 Through hole 301 Adhesion evaluation sample 302 Reinforced glass plate 303 EVA sheet 304 Sealing material measurement sample 305 Copper foil

Claims (8)

An ethylene / α-olefin copolymer, an organic peroxide, a silane coupling agent containing an epoxy group, and a silane coupling agent containing a (meth) acryloyl group,
The mass part of the silane coupling agent containing an epoxy group with respect to 100 parts by mass of the ethylene / α-olefin copolymer is W (SC (A)), and the (meth) acryloyl group with respect to 100 parts by mass of the ethylene / α-olefin copolymer. The content of the silane coupling agent in the composition satisfies the following (formula 1) and (formula 2) when the silane coupling agent containing is W (SC (B)). Solar cell encapsulant.
0.1 <W (SC (B)) (Formula 1)
0.8 <W (SC (A)) / W (SC (B)) <3 (Formula 2)   The solar cell encapsulant according to claim 1, wherein the ethylene / α-olefin copolymer is a linear low density polyethylene.   The solar cell encapsulant according to claim 1 or 2, wherein the composition comprises a carbon dioxide carbonate ion scavenger.   4. The solar cell encapsulant according to claim 3, wherein the carbon dioxide carbonate ion scavenger is at least one of magnesium oxide and magnesium hydroxide.   The solar cell encapsulant according to any one of claims 1 to 4, wherein the composition further contains at least one of a triazine ultraviolet absorber and a benzotriazole ultraviolet absorber. .   The solar cell encapsulant according to any one of claims 1 to 5, wherein the composition contains an insulating filler having an average particle diameter of 10 µm or more and 200 µm or less.   The solar cell module using the sealing material for solar cells of any one of Claims 1-6.   The back contact type solar cell module using the sealing material for solar cells of any one of Claims 1-6.

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