JP4233071B2 - Solar cell sealing material and solar cell module - Google Patents

Description

【００５０】
（２）アミノカルボン酸
１２ーアミノドデカン酸…宇部興産（株）製
（３）ポリアミドオリゴマー
ＰＡＯ（重合度２１のε−カプロラクタムオリゴマーの片末端をｎ−ブチルアミンで封止）
（４）ポリプロピレンワックス
ハイワックスＮＰ５０５（プロピレン・エチレン共重合体、融点：１４３〜１５０℃、数平均分子量：９４００、三井化学（株）製）
（５）エチレン・αーオレフィン共重合体
エチレン・ブチレン・オレフィン結晶ブロック共重合体（数平均分子量３０００００）
（６）ラジカル発生剤
２，５−ジメチルー２，５−ビス（tert−ブチルパーオキシ）ヘキシン−３（アトケム吉富（株））
（７）架橋助剤
イソシアヌル酸トリアリル（東京化成工業（株））
【００５１】
２．物性評価方法
（１）貯蔵弾性率（Ｅ’）
貯蔵弾性率を下記の装置を用い、下記条件で測定した。

【００５２】
（２）全光線透過率
スガ試験機製ヘーズメーターを用いて、ＪＩＳ Ｋ７１０５の方法で評価した。 プレスシートサンプル厚み：０．５ｍｍ
【００５３】
（３）接着性評価
（Ａ）対ガラス
太陽電池用の上部透明保護材である透明ガラス板とＰＥＴフイルムとの間に、後記する方法で作成した０．５ｍｍ厚みのプレスシートを挟んで真空ラミネーター内に仕込み、１６０℃に温調したホットプレート上に載せて１５分間加熱し、ガラス板／プレスシート／ＰＥＴフイルムの積層体を作成した。この積層体について、ガラスとプレスシート間を手で剥がしてその剥がれ具合を観察し、下記２段階で評価した。
○：接着性良好 ×：接着性不良
【００５４】
（Ｂ）対アルミ板
アルミ板とＰＥＴフイルムとの間に後記する方法で作成した０．５ｍｍ厚みの上記プレスシートを挟んで真空ラミネーター内に仕込み、１６０℃に温調したホットプレート上に載せて１５分間加熱し、アルミ板／プレスシート／ＰＥＴフイルムの積層体を作成した。この積層体について、アルミ板とプレスシート間を手で剥がしてその剥がれ具合を観察し、下記２段階で評価した。
○：接着性良好 ×：接着性不良
【００５５】
［実施例１〜３］
各原料を表２で示す配合比で配合し、小型加圧ニーダーで加熱混練した後、プレス成形（成形温度１６０℃）により、厚さ０．５ｍｍ及び２ｍｍのシートを作成した。これらのシートを用いて上記（１）〜（３）の方法により、貯蔵弾性率、全光線透過率、接着性を評価した。結果を表２に示す。
【００５６】
［実施例４〜５］
単軸押出機（スクリュー径３０ｍｍ、Ｌ／Ｄ＝３２）に、アイオノマーとポリアミドオリゴマーを表２に記載した比率で配合して供給し、樹脂温度２３０℃で押出速度２ｋｇ／ｈの条件で混練して押出し、押出機から出るストランドをカッティングしてポリアミドオリゴマー変性物のペレットを得た。このペレットからプレス成形（成形温度１６０℃）にて厚さ０．５ｍｍ及び２ｍｍのシートを作成した。これらのシートを用いて上記（１）〜（３）の方法により、貯蔵弾性率、全光線透過率、接着性を評価した。結果を表２に示す。
【００５７】
［比較例１］
ＥＭＡＡ−２を用い、上記実施例と同様にしてプレスシートを作成し、同様の評価を行った。結果を表２に併記する。
【００５８】
【表２】

【００５９】
［実施例６〜８］
各原料を表３で示す配合比で配合し、小型加圧ニーダーで加熱混練した後、プレス成形（成形温度１６０℃）により、厚さ０．５ｍｍ及び２ｍｍのシートを作成した。これらのシートを用いて上記（１）〜（３）の方法により、貯蔵弾性率、全光線透過率、接着性を評価した。結果を表３に示す。
【００６０】
［比較例２］
ＥＭＡＡ−１を用い、上記実施例と同様にしてプレスシートを作成し、同様の評価を行った。結果を表３に併記する。
【００６１】
【表３】

【００６２】
表２、３に示すように本発明に係る封止材料は、エチレン・不飽和カルボン酸共重合体単体と比べて、透明性、接着性を大きく損なうことなく、高温域での貯蔵弾性率が優れている。
【００６３】
【発明の効果】
本発明の封止材料は、上部保護材としてのガラス、下部基板保護材としての金属、太陽電池素子などに対して、過酸化物やシランカップリング剤を使用しなくても優れた接着性を示し、また透明性、耐熱性においても優れている。とくに適切な変性物を使用することにより、例えば、１５０℃における貯蔵弾性率が１．０×１０³Ｐａ以上、好ましくは５．０×１０³Ｐａ以上で、光線透過率が９０％以上、好ましくは９１％以上の封止材料を容易に得ることができる。したがって本発明によれば、太陽電池モジュールの使用時に温度上昇しても、封止材料が流動したり変形したりするトラブルを回避することが可能であり、太陽電池の外観を損なうことも無い。また上記のような添加剤の使用が省略できるので、太陽電池モジュール製造工程における生産性を著しく高めることが可能であり、太陽電池モジュールの製造コストを大幅に低減させることが可能である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sealing material for a solar cell element in a solar cell module and a solar cell module using the same. More specifically, the present invention relates to a sealing material that is easy to form a solar cell module and excellent in transparency, heat resistance, adhesiveness, and the like.
[0002]
[Prior art]
In recent years, solar cells, which are attracting attention as a clean energy source, have come to be used for ordinary homes, but have not yet become sufficiently popular. The reason is that it is difficult to say that the performance of the solar cell itself is sufficiently excellent, so that the module has to be made large, the productivity in module manufacturing is low, and as a result, it is expensive.
[0003]
Solar cell modules generally protect solar cell elements such as silicon, gallium-arsenide, copper-indium-selenium with an upper transparent protective material and a lower substrate protective material, and fix the solar cell element and protective material with a sealing material. And packaged. For this reason, as a solar cell sealing material, transparency and adhesiveness with each upper and lower protective material are requested | required.
[0004]
For example, as a sealing material for a solar cell element in a solar cell module, an ethylene / vinyl acetate copolymer having a high vinyl acetate content is used from the viewpoints of flexibility, transparency, and the like. However, since the heat resistance and adhesiveness are insufficient, it is necessary to use an organic peroxide or a silane coupling agent in combination. In this case, it was necessary to employ a two-stage process in which a sheet of an ethylene / vinyl acetate copolymer containing these additives was prepared and the solar cell element was sealed using the obtained sheet. In the production stage of this sheet, it is necessary to form at a low temperature so that the organic peroxide is not decomposed. Therefore, the extrusion speed cannot be increased, and in the sealing stage of the solar cell element, in the laminator It takes two steps, consisting of a process of temporary bonding for several minutes to ten and several minutes and a process of main bonding for several tens of minutes to one hour at a high temperature at which the organic peroxide decomposes in the oven. It was necessary to go through an adhesion process. Therefore, it takes time and labor to manufacture the solar cell module, which is one of the factors that increase the manufacturing cost.
[0005]
In order to solve such problems, the present inventors have shown excellent adhesion to protective materials such as glass and metal in Japanese Patent Application No. 10-294354 without using organic peroxides, and transparency. As an alternative material having excellent heat resistance, it has been proposed to use an ethylene / unsaturated carboxylic acid copolymer having an unsaturated carboxylic acid content of 4% by weight or more and a melting point of 85 ° C. or more, or an ionomer thereof.
[0006]
However, when the solar cell is used, the temperature may rise to a maximum of 90 to 100 ° C. In the proposed material, the sealing material may flow and deform due to a decrease in storage elastic modulus.
[0007]
[Problems to be solved by the invention]
Therefore, the present inventors have earnestly devised an improved formulation that improves storage elastic modulus in a high temperature range without substantially impairing transparency and adhesiveness and hardly causes flow or deformation even when the temperature of the solar cell module rises. Study was carried out. As a result, by using an ethylene / unsaturated carboxylic acid copolymer or a modified product of its ionomer as described later, the elastic modulus at high temperature is improved, and transparency and adhesiveness are not substantially impaired. And reached the present invention.
[0008]
Accordingly, an object of the present invention is to provide a solar cell encapsulating material excellent in transparency, heat resistance, adhesiveness and the like. Another object of the present invention is to provide a solar cell module using such a solar cell sealing material.
[0009]
[Means for Solving the Problems]
The present invention is based on the following (A), (B) and (C) of an ethylene / unsaturated carboxylic acid copolymer or ionomer having an unsaturated carboxylic acid content of 4% by weight or more and a melting point of 80 ° C. or more. Either a modified product selected, or such a modified product and an unsaturated carboxylic acid copolymer having an unsaturated carboxylic acid content of 4% by weight or more and a melting point of 80 ° C. or higher, or a blend of its ionomers. It is related with the solar cell element sealing material in the solar cell module characterized by using.
(A) An oligoamide-modified product obtained by melt-kneading the ethylene / unsaturated carboxylic acid copolymer or its ionomer with a nylon salt or aminocarboxylic acid.
(B) A modified polyamide oligomer obtained by melt-kneading the ethylene / unsaturated carboxylic acid copolymer or its ionomer and a polyamide oligomer having a primary amino group at one or both ends.
(C) Melting and kneading the above ethylene / unsaturated carboxylic acid copolymer or its ionomer, a polypropylene wax having a number average molecular weight of 50000 or less, an ethylene / α-olefin copolymer having a number average molecular weight of 100000 or more, a radical generator and a crosslinking aid. Modified polypropylene wax.
[0010]
The present invention also relates to a solar cell module using the modified product as a solar cell element sealing material.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
The sealing material of the present invention seals a solar cell element, an upper transparent protective material, and a lower substrate protective material in a solar cell module to form a solar cell module.
[0012]
The ethylene / unsaturated carboxylic acid copolymer or ionomer thereof used as the raw material of the modified product used as the sealing material of the present invention has an unsaturated carboxylic acid content of 4% by weight or more, preferably 5 to 20% by weight, The melting point by DSC is 80 ° C. or higher, preferably 85 to 105 ° C. Such a copolymer or its ionomer has an advantage of having excellent transparency without using an ethylene copolymer having a high comonomer content, as in the case of an ethylene / vinyl acetate copolymer.
[0013]
Here, examples of the unsaturated carboxylic acid include acrylic acid, methacrylic acid, maleic acid, maleic anhydride, and acrylic acid or methacrylic acid is particularly preferable. As the above-mentioned ethylene / unsaturated carboxylic acid copolymer, a copolymer obtained by copolymerizing vinyl ester or (meth) acrylic acid ester may be used since it is effective for imparting flexibility. Since those containing these copolymer components have a low melting point, those containing a large amount cannot be used.
[0014]
Examples of the ionomer of the ethylene / unsaturated carboxylic acid copolymer in the present invention include alkali metals such as lithium and sodium, and polyvalent metals such as calcium, magnesium, zinc and aluminum. . The advantage of using such an ionomer is transparency and high storage elastic modulus at high temperature, and it is desirable to use a neutralization degree of, for example, about 80% or less. Then, it is not a good idea to use a material having a very high degree of neutralization. For example, it is preferable to use a material having a degree of neutralization of 60% or less, particularly 30% or less.
[0015]
When the above copolymer or its ionomer having an unsaturated carboxylic acid content of less than 4% by weight is used, a product having excellent transparency cannot be obtained, and the adhesiveness is also insufficient. In addition, when the unsaturated carboxylic acid content is increased, more excellent transparency can be obtained, but problems such as a lower melting point and increased hygroscopicity arise. In the present invention, since the melting point is specified to be 80 ° C. or higher, the content is naturally limited.
[0016]
In the present invention, when a copolymer or ionomer having a melting point lower than 80 ° C. is used, it is difficult to obtain a modified product having sufficient heat resistance even if the modification described below is performed, and the solar cell element sealing When used as a material, there is a risk of deformation due to temperature rise when using solar cells, and when manufacturing a solar cell module by thermocompression bonding, these sealing materials may flow out more than necessary and cause burrs. It is not preferable.
[0017]
As the copolymer or its ionomer, it is preferable to use a copolymer having a melt flow rate (MFR) at 190 ° C. and a load of 2160 g of 0.1 to 500 g / 10 minutes, particularly 1 to 200 g / 10 minutes. When a material with a low MFR is used, a modified product with a low MFR can be obtained. Even if a material with a slightly lower melting point is used, there is an advantage that troubles due to the flow of the sealing material as described above hardly occur. If a material having a very low MFR is used, workability deteriorates. On the other hand, if a product with too high MFR is used, the MFR of the modified product will also be high, and the amount of sticking out of the end and sticking into the laminate will be increased when creating the module. Becomes worse.
[0018]
As the above-mentioned ethylene / unsaturated carboxylic acid copolymer or its ionomer, two or more kinds may be used. For example, those having different acid contents and MFR, or those having different metal species in the ionomer may be arbitrarily selected. Two or more types can be used in combination.
[0019]
In the present invention, the above-mentioned ethylene / unsaturated carboxylic acid copolymer selected from (A), (B) and (C) or a modified product of its ionomer is used.
[0020]
The modified product (A) is obtained by melt-kneading an ethylene / unsaturated carboxylic acid copolymer or its ionomer and a nylon salt or aminocarboxylic acid, and the ethylene / unsaturated carboxylic acid copolymer or its ionomer. It is considered to have a structure in which an oligoamide is grafted to a carboxyl group.
[0021]
The nylon salt that can be used for the production of the modified product (A) is a salt of diamine and dicarboxylic acid, such as succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid. Aliphatic dicarboxylic acid, cycloaliphatic dicarboxylic acid such as cyclohexanedicarboxylic acid, aromatic dicarboxylic acid such as terephthalic acid and isophthalic acid, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, octamethylenediamine, decamethylene Aliphatic diamine such as diamine, 2,4,4, -trimethylhexamethylenediamine, 1,3-bisaminomethylcyclohexane, 1,4-bisaminocyclohexane, bis (p-aminocyclohexyl) methane Group diamine, 1,3-xylidenediamine It can be exemplified salts with aromatic diamines such as.
[0022]
Examples of aminocarboxylic acids that can be used for the production of the modified product (A) include 6-aminohexanoic acid, 8-aminooctanoic acid, 10-aminodecanoic acid, 11-aminoundecanoic acid, 12-aminododecanoic acid, and the like. Can do.
[0023]
In the production method of the modified product (A), 1 to 40 parts by weight, particularly 2 to 30 parts by weight of nylon salt or aminocarboxylic acid is used per 100 parts by weight of ethylene / unsaturated carboxylic acid copolymer or ionomer. Is preferred.
[0024]
The modified product (A) can be produced by kneading using a kneading apparatus such as an extruder under a condition that each raw material melts, preferably at a temperature of 200 to 300 ° C. As the modified product (A), it is desirable to use a grafted oligoamide unit of 0.5 to 40% by weight, particularly 1 to 30% by weight, and MFR at 240 ° C. and 2160 g load is 0.05 to 100 g / It is preferable to use those for 10 minutes, particularly 0.1 to 50 g / 10 minutes.
[0025]
As a solar cell sealing material, the reaction product obtained by melt kneading may be used as it is, but if necessary, a purification operation such as extraction removal of unreacted nylon salt or aminocarboxylic acid was performed. Things may be used. As an example of a method for producing such a modified product (A), for example, the method disclosed in JP-A-10-287749 can be mentioned.
[0026]
The modified product (B) that can be used in the present invention is a modified polyamide oligomer of an ethylene / unsaturated carboxylic acid copolymer or its ionomer. In this case, as the ethylene / unsaturated carboxylic acid copolymer or its ionomer, it is desirable to use an ionomer that is at least partially neutralized with a divalent metal cation, preferably a divalent transition metal cation. In other words, the ionomer neutralized with a transition metal cation readily coordinates to the carboxyl salt of the terminal primary amino group of the polyamide oligomer to form an ammine complex, and reacts with the carboxyl group to form an ammonium salt. And bonded to the polyamide oligomer. This is because a modified product excellent in transparency, heat resistance, and workability, which is suitable as a solar cell sealing material, can be easily obtained.
[0027]
However, when only the transition metal ionomer is used, a modified product with good processability may not be obtained depending on the type of polyamide oligomer and the amount of use thereof. In this case, for example, it is effective to replace an amount of half or less of the transition metal ionomer with an alkali metal ionomer. In other words, the terminal primary amino group of the polyamide oligomer does not coordinate with the carboxyl salt of the alkali metal ionomer, so it does not form an ammine complex salt, and depending on the degree of neutralization, it reacts with the carboxyl group to form an ammonium salt and bond. However, since the amount thereof is smaller than that of the transition metal ionomer, the original processability and transparency of the ionomer are maintained, so that it acts as an effective diluent.
[0028]
The polyamide oligomer that can be used for the production of the modified product (B) has a primary amino group at one end or both ends, and the degree of polymerization is about 4 to 40. This is because if the degree of polymerization of the polyamide oligomer used is too large, it becomes difficult to complex-bond with the transition metal ionomer, the heat resistance improving effect is not sufficient, and the transparency is also lowered. Examples of polyamide oligomers include oligomers such as nylon 4, nylon 6, nylon 12, and nylon 610.
[0029]
The amount of the polyamide oligomer used in the production of the modified product (B) is 1 to 30 parts by weight for those having a primary amino group at one end and 1 to 1 for those having a primary amino group at both ends per 100 parts by weight of the ionomer. About 15 parts by weight. If a polyamide oligomer having a primary amino group at one end is used in a large amount, unreacted substances may remain, and transparency is impaired. On the other hand, if too much polyamide oligomer having primary amino groups at both ends is used, it becomes difficult to obtain a modified product with good processability.
[0030]
The modified product (B) can be obtained by kneading an ionomer and a polyamide oligomer at a temperature equal to or higher than their melting points, preferably 200 to 300 ° C. The modified product (B) as the solar cell sealing material preferably has a MFR of 0.1 to 50 g / 10 min at 190 ° C. and a load of 2160 g.
[0031]
The modified product (C) that can be used in the present invention is an ethylene / unsaturated carboxylic acid copolymer or an ionomer thereof, a polypropylene wax having a number average molecular weight of 50000 or less, and an ethylene / α-olefin copolymer having a number average molecular weight of 100,000 or more. This is a modified polypropylene wax obtained by melt-kneading a coalescence, a radical generator and a crosslinking aid.
[0032]
The polypropylene wax is a homopolymer of propylene or a copolymer of propylene and a small amount of other α-olefins such as ethylene, 1-butene, etc., and is a method of directly producing by polymerization in the presence of a stereospecific catalyst, It can be obtained by, for example, a method of producing by thermally decomposing high molecular weight polypropylene obtained by polymerization in the presence of a specific catalyst. The number average molecular weight is 50000 or less, preferably in the range of 100 to 35000. In order to obtain a modified product having excellent heat resistance, those having a melting point of 120 ° C. or higher are preferred. Therefore, when using the said copolymer, it is desirable that the alpha olefin of a copolymerization component exists in the range of 10 weight% or less, especially 0.5-6 weight%.
[0033]
The ethylene / α-olefin copolymer having a number average molecular weight of 100,000 or more used in the production of the modified product (C) is preferably one of ethylene having an ethylene content of 5 to 50% by weight and α-olefin having 3 or more carbon atoms. It is a copolymer composed of two or more kinds. When a copolymer having an ethylene content other than the above range is used, the compatibility with the polypropylene wax component is poor, and it becomes difficult to control the moldability of the finally obtained modified product. Specific examples of the copolymer include propylene / ethylene copolymer, 1-butene / ethylene copolymer, 1-hexene / ethylene copolymer, 1-octene / ethylene copolymer, 1-decene / ethylene copolymer. Examples include coalescence.
[0034]
The radical generator used in the production of the modified product (C) is a compound having a molecule that generates radicals upon heating, and examples thereof include inorganic peroxides, organic peroxides, diazo compounds, and disulfide compounds. it can. Particularly preferred are organic peroxides such as dicumyl peroxide, ditert-butyl peroxide, 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane, 2,5-dimethyl-2. , 5-Di (tert-butylperoxy) hexyne-3, 1,3-bis (tert-butylperoxycyisopropyl) benzene, 1,1-bis (tert-butylperoxy) -3,3,5-trimethyl Cyclohexane, n-butyl-4,4-bis (tert-butylperoxy) valerate, benzoyl peroxide, p-chlorobenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, tert-butylperoxybenzoate, tert-butyl Peroxyisopropyl carbonate, diacetyl peroxide, lauroyl peroxide, tert And the like can be exemplified butyl cumyl peroxide.
[0035]
The crosslinking aid used in the production of the modified product (C) is selected from a compound having a double bond or a compound containing an atomic group having radical scavenging ability. For example, sulfur, metaphenylene bismaleimide, quinone dioxime 1,2-polybutadiene, triallyl cyanurate, diallyl phthalate, ethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, triethylene glycol dimethacrylate, triallyl isocyanurate, and the like.
[0036]
The ratio of each component used in the production of the modified product (C) is 50 to 98 parts by weight of an ethylene / unsaturated carboxylic acid copolymer or ionomer thereof, 1 to 49 parts by weight of polypropylene wax, and 1 to 49 parts of ethylene / α-olefin copolymer. The ratio is 0.01 to 5 parts by weight of a radical generator and 0.01 to 5 parts by weight of a crosslinking aid with respect to 100 parts by weight of a total of 100 parts by weight and these three components. If the amount of the radical generator or crosslinking aid used is too small, the heat resistance of the modified product (C) is insufficient, and if the amount is too large, the processability of the modified product (C) is deteriorated and the appearance is good. It becomes difficult to obtain a simple sealing material.
[0037]
The modified product (C) is produced by melting each of the above components using a Banbury mixer, a kneader, an extruder, etc. under the conditions in which the above three polymer components are melted and the radical generator is sufficiently decomposed. It can be performed by kneading. A suitable melt-kneading temperature is 150 ° C. or higher, particularly 180 to 290 ° C. At this time, the ethylene / unsaturated carboxylic acid copolymer or its ionomer, polypropylene wax, and ethylene / α-olefin copolymer may be mixed in advance, but at the time of melt-kneading in the presence of a radical generator, other 4 It is important that the components coexist, whereby a modified product with good heat resistance can be obtained. Even if an ethylene / unsaturated carboxylic acid copolymer or its ionomer and polypropylene wax are melt-kneaded in the presence of a radical generator, a modified product having fluidity suitable for molding cannot be obtained. Even if the copolymer or its ionomer and ethylene / α-olefin copolymer are melt-kneaded in the presence of a radical generator, a modified product having excellent heat resistance cannot be obtained.
[0038]
The modified product (C) thus obtained can be recovered in the form of granules, rods, flakes, pellets and the like. As the sealing material, it is preferable to use a modified material having a MFR of about 0.1 to 30 g / 10 min at 190 ° C. and a load of 2160 g.
[0039]
In the present invention, the modified product selected from the above (A), (B) and (C) is used as a solar cell sealing material, and (A), (B) and (C) are respectively used. They may be used alone or in combination, such as (A) and (B), (B) and (C), (C) and (A), or (A), (B), and (C). It can also be used. In order to improve processability and transparency, these modified products may be blended with an ethylene / unsaturated carboxylic acid copolymer or an ionomer thereof having a melting point of 80 ° C. or higher, preferably 85 to 105 ° C. it can. Allowable blending amount of ethylene / unsaturated carboxylic acid copolymer or its ionomer varies depending on the type and degree of modification of (A), (B), (C), etc. It is preferable to keep it below the weight.
[0040]
Various additives can be blended in the sealing material of the present invention as necessary. As such an additive, when blended with the sealing material on the light receiving side of the solar cell element, it is not preferable to impair the transparency, but blended with the sealing material on the opposite surface of the solar cell element on the light receiving side. You are not subject to such restrictions. Specific examples of such additives include antioxidants, light stabilizers, ultraviolet absorbers, colorants, light diffusing agents, flame retardants, discoloration inhibitors, and silane coupling agents. Or an inorganic filler can also be mix | blended within the range which does not impair transparency.
[0041]
A solar cell module can be manufactured by using the sealing material of the present invention and fixing the solar cell element with upper and lower protective materials. Examples of such solar cell modules include various types. For example, a transparent protective material / encapsulant / solar cell element / encapsulant / lower protective material sandwiched between both sides of the solar cell element, and formed on the inner peripheral surface of the lower substrate protective material A structure in which a sealing material and an upper transparent protective material are formed on the solar cell element, and a sealing material and a lower protective material are formed on the solar cell element formed on the inner peripheral surface of the upper transparent protective material. The thing of the structure to be made can be mentioned.
[0042]
Solar cell elements include single-crystal silicon, polycrystalline silicon, amorphous silicon, and other silicon systems, and gallium-arsenic, copper-indium-selenium, cadmium-tellurium, and other III-V group and II-VI group compound semiconductor systems. Various solar cell elements can be used, and the sealing material of the present invention can be applied to sealing any of these solar cell elements.
[0043]
Examples of the upper protective material constituting the solar cell module include glass, acrylic resin, polycarbonate, polyester, and fluorine-containing resin. The lower protective material is a single or multi-layer sheet of metal or various thermoplastic resin films, for example, metals such as tin, aluminum, stainless steel, inorganic materials such as glass, polyester, inorganic vapor-deposited polyester, fluorine-containing A single layer or multilayer sheet of resin, polyolefin, etc. can be exemplified. The sealing material of this invention shows favorable adhesiveness with respect to these upper or lower protective materials.
[0044]
In manufacturing a solar cell module, a sheet having the above-described configuration is formed by a method similar to the conventional method in which a sheet of the sealing material of the present invention is prepared in advance and pressure-bonded at a temperature at which the sealing material melts. be able to. In this case, since the sealing material does not contain an organic peroxide, it is possible to perform sheet molding of the sealing material at a high temperature with high productivity, and it is necessary to go through a two-step bonding process in forming the module. And can be completed in a short time at a high temperature. Furthermore, if a method of laminating with the solar cell element, the upper protective material or the lower protective material by extrusion coating the sealing material of the present invention is adopted, a solar cell module can be manufactured in one step without bothering to form a sheet. Is possible. Thus, if the sealing material of the present invention is used, the productivity of the module can be remarkably improved.
[0045]
When the sheet of the sealing material of the present invention is made in advance, a multilayer structure having an adhesive layer can be formed. That is, although the sealing material of the present invention has sufficient adhesiveness, there may be a concern about a slight decrease in adhesive strength due to various modifications. In this case, an adhesive layer having a thickness of about 5 to 100 μm can be provided on either one or both of the upper and lower sides so as not to affect the storage elastic modulus in the high temperature range, thereby suppressing a decrease in adhesive force. In this case, if the thickness of the adhesive layer is less than 5 μm, the improvement of the adhesive strength is not sufficient, and molding becomes difficult. On the other hand, if the thickness of the adhesive layer exceeds 100 μm, the elastic modulus in the high temperature range may be lowered. The adhesive layer used for such a purpose is not limited to the ethylene / unsaturated carboxylic acid copolymer or its ionomer used in the present invention. For example, a silane-modified product of olefin polymer or maleic anhydride is used. An acid-modified product can also be used.
[0046]
Even if any of the above methods is adopted, the thickness of the sealing material is arbitrary, and can be, for example, about 0.1 to 1 mm.
[0047]
【Example】
EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention concretely, this invention is not limited to these Examples. In addition, the raw material used for the Example and the comparative example and the evaluation method of a physical property are as follows.
[0048]
1. material
(1) Ethylene / unsaturated carboxylic acid copolymer and ionomer
The ethylene / methacrylic acid copolymer (EMAA) and its ionomer shown in Table 1 were used.
[0049]
[Table 1]

[0050]
(2) Aminocarboxylic acid
12-aminododecanoic acid ... made by Ube Industries, Ltd.
(3) Polyamide oligomer
PAO (one end of ε-caprolactam oligomer having a polymerization degree of 21 is sealed with n-butylamine)
(4) Polypropylene wax
High wax NP505 (propylene / ethylene copolymer, melting point: 143 to 150 ° C., number average molecular weight: 9400, manufactured by Mitsui Chemicals, Inc.)
(5) Ethylene / α-olefin copolymer
Ethylene / Butylene / Olefin Crystal Block Copolymer (Number Average Molecular Weight 300000)
(6) Radical generator
2,5-Dimethyl-2,5-bis (tert-butylperoxy) hexyne-3 (Atchem Yoshitomi Corp.)
(7) Crosslinking aid
Triallyl isocyanurate (Tokyo Chemical Industry Co., Ltd.)
[0051]
2. Physical property evaluation method
(1) Storage elastic modulus (E ')
The storage elastic modulus was measured using the following apparatus under the following conditions.

[0052]
(2) Total light transmittance
Evaluation was made by the method of JIS K7105 using a haze meter manufactured by Suga Test Instruments. Press sheet sample thickness: 0.5mm
[0053]
(3) Adhesive evaluation
(A) Anti-glass
Hot heated in a vacuum laminator with a 0.5 mm thick press sheet created by the method described below between a transparent glass plate, which is an upper transparent protective material for solar cells, and a PET film, and adjusted to 160 ° C. It was placed on the plate and heated for 15 minutes to prepare a laminate of glass plate / press sheet / PET film. About this laminated body, between glass and a press sheet was peeled by hand, the peeling condition was observed, and the following two steps evaluated.
○: Adhesive good ×: Adhesive poor
[0054]
(B) Aluminum plate
The 0.5 mm thick press sheet prepared by the method described later is sandwiched between an aluminum plate and a PET film, charged in a vacuum laminator, placed on a hot plate adjusted to 160 ° C., and heated for 15 minutes. A laminate of plate / press sheet / PET film was prepared. About this laminated body, it peeled between the aluminum plate and the press sheet | seat by hand, the peeling condition was observed, and the following two steps evaluated.
○: Adhesive good ×: Adhesive poor
[0055]
[Examples 1 to 3]
Each raw material was blended at a blending ratio shown in Table 2 and heated and kneaded with a small pressure kneader, and then sheets with thicknesses of 0.5 mm and 2 mm were prepared by press molding (molding temperature 160 ° C.). Using these sheets, the storage elastic modulus, total light transmittance, and adhesiveness were evaluated by the methods (1) to (3) above. The results are shown in Table 2.
[0056]
[Examples 4 to 5]
In a single-screw extruder (screw diameter 30 mm, L / D = 32), the ionomer and polyamide oligomer are blended and supplied at the ratio shown in Table 2, and kneaded at a resin temperature of 230 ° C. and an extrusion speed of 2 kg / h. Then, the strand exiting the extruder was cut to obtain polyamide oligomer-modified pellets. Sheets having a thickness of 0.5 mm and 2 mm were prepared from the pellets by press molding (molding temperature 160 ° C.). Using these sheets, the storage elastic modulus, total light transmittance, and adhesiveness were evaluated by the methods (1) to (3) above. The results are shown in Table 2.
[0057]
[Comparative Example 1]
Using EMAA-2, a press sheet was prepared in the same manner as in the above example, and the same evaluation was performed. The results are also shown in Table 2.
[0058]
[Table 2]

[0059]
[Examples 6 to 8]
Each raw material was blended at a blending ratio shown in Table 3 and heated and kneaded with a small pressure kneader, and then sheets with thicknesses of 0.5 mm and 2 mm were prepared by press molding (molding temperature 160 ° C.). Using these sheets, the storage elastic modulus, total light transmittance, and adhesiveness were evaluated by the methods (1) to (3) above. The results are shown in Table 3.
[0060]
[Comparative Example 2]
Using EMAA-1, a press sheet was prepared in the same manner as in the above example, and the same evaluation was performed. The results are also shown in Table 3.
[0061]
[Table 3]

[0062]
As shown in Tables 2 and 3, the sealing material according to the present invention has a storage elastic modulus in a high temperature range without significantly impairing transparency and adhesiveness as compared with the ethylene / unsaturated carboxylic acid copolymer alone. Are better.
[0063]
【The invention's effect】
The sealing material of the present invention has excellent adhesion to glass as an upper protective material, metal as a lower substrate protective material, solar cell element, etc. without using a peroxide or a silane coupling agent. It is also excellent in transparency and heat resistance. By using a particularly suitable modified product, for example, the storage elastic modulus at 150 ° C. is 1.0 × 10 ^Three Pa or more, preferably 5.0 × 10 ^Three A sealing material having a light transmittance of 90% or higher, preferably 91% or higher can be easily obtained at Pa or higher. Therefore, according to the present invention, even when the temperature rises when the solar cell module is used, it is possible to avoid the trouble that the sealing material flows or deforms, and the appearance of the solar cell is not impaired. In addition, since the use of the additive as described above can be omitted, the productivity in the solar cell module manufacturing process can be remarkably increased, and the manufacturing cost of the solar cell module can be greatly reduced.

Claims (4)

Modified products selected from the following (A), (B) and (C) of ethylene / unsaturated carboxylic acid copolymers or ionomers having an unsaturated carboxylic acid content of 4% by weight or more and a melting point of 80 ° C. or more. The solar cell element sealing material in the solar cell module characterized by using.
(A) An oligoamide-modified product obtained by melt-kneading the ethylene / unsaturated carboxylic acid copolymer or its ionomer with a nylon salt or aminocarboxylic acid.
(B) A modified polyamide oligomer obtained by melt-kneading the ethylene / unsaturated carboxylic acid copolymer or its ionomer and a polyamide oligomer having a primary amino group at one or both ends.
(C) Melting and kneading the above ethylene / unsaturated carboxylic acid copolymer or its ionomer, a polypropylene wax having a number average molecular weight of 50000 or less, an ethylene / α-olefin copolymer having a number average molecular weight of 100000 or more, a radical generator and a crosslinking aid. Modified polypropylene wax. The modified product selected from (A), (B) and (C) is an ethylene / unsaturated carboxylic acid copolymer having an unsaturated carboxylic acid content of 4% by weight or more and a melting point of 80 ° C. or more, or an ionomer thereof. The solar cell element sealing material according to claim 1, which is used by blending. The solar cell element sealing material according to claim 1 or 2, wherein the storage elastic modulus at 150 ° C is 10 ³ Pa or more and the total light transmittance is 90% or more. The solar cell module using the solar cell element sealing material of Claims 1-3.