JP2001119056A - Solar cell sealing material and solar cell module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solar cell sealing material, with which a solar cell module can be easily formed and which has superior transparency, heat resistance, adhesion and so forth. SOLUTION: This solar cell sealing material is obtained by modifying a copolymer of ethylene and unsaturated carboxylic acid, containing 4 weight % or more of unsaturated carboxylic acid and having a melting point of 80 deg.C or higher or an ionomer thereof with nylon salt, aminocarboxylic acid, polyamide oligomer or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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 facilitates formation of a solar cell module and has excellent transparency, heat resistance, adhesiveness, and the like.

[0002]

2. Description of the Related Art In recent years, solar cells, which have attracted attention as a clean energy source, have been used for general homes, but have not yet been widely used. The reasons are that it is difficult to say that the performance of the solar cell itself is sufficiently excellent, so that the module must be large, the productivity in module production is low, and as a result, the cost is high.

[0003] Solar cell modules are generally made of silicon,
Protecting solar cell elements such as gallium-arsenic and copper-indium-selenium with upper transparent protective material and lower substrate protective material,
The solar cell element and the protective material are fixed with a sealing material and packaged. For this reason, the solar cell sealing material is required to have good transparency and good adhesion to the upper and lower protective materials.

For example, at present, 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 viewpoint of flexibility and transparency. However, because of its insufficient heat resistance and adhesiveness, it was necessary to use an organic peroxide, a silane coupling agent, and the like in combination. In this case, it is necessary to adopt a two-step process of preparing a sheet of an ethylene / vinyl acetate copolymer containing these additives and sealing the solar cell element using the obtained sheet. In the production stage of this sheet, it is necessary to mold at a low temperature such that the organic peroxide does not decompose, so that the extrusion molding speed cannot be increased, and in the sealing stage of the solar cell element, the laminator is used. A two-stage process consisting of a temporary bonding process for several minutes to several tens of minutes and a full bonding process for several tens of minutes to one hour at a high temperature at which the organic peroxide decomposes in an oven. It had to go through a bonding process. Therefore, it takes time and effort to manufacture the solar cell module, which is one of the factors that increase the manufacturing cost.

In response to such a problem, the present inventors have disclosed in Japanese Patent Application No. 10-294354 an excellent adhesion to protective materials such as glass and metal without using an organic peroxide. Also, as an alternative material having excellent transparency and heat resistance, it is 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. did.

However, when solar cells are used, the maximum is 90.
In some cases, the temperature may rise to 100 ° C., and in the above-mentioned proposed material, the sealing material may flow and deform due to a decrease in storage modulus.

[0007]

SUMMARY OF THE INVENTION Accordingly, the present inventors
The storage formulation in the high-temperature region was improved without substantially impairing the transparency and the adhesiveness, and an improved formulation that does not easily flow or deform even when the temperature of the solar cell module rises was studied diligently. As a result, ethylene
The inventors have found that by using an unsaturated carboxylic acid copolymer or a modified ionomer thereof, the elastic modulus in a high temperature range is improved, and the transparency and adhesion are not substantially impaired, and the present invention has been achieved.

Accordingly, it is an object of the present invention to provide a solar cell encapsulating material having excellent 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]

According to the present invention, there is provided 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 (A). , 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, selected from the group consisting of (B) and (C). Alternatively, the present invention relates to a solar cell element encapsulating material for a solar cell module, wherein any one of the ionomer blends is used. (A) An oligoamide-modified product obtained by melt-kneading the above-mentioned 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 above-mentioned ethylene / unsaturated carboxylic acid copolymer or its ionomer and a polyamide oligomer having a primary amino group at one or both terminals. (C) Melt kneading the above-mentioned ethylene / unsaturated carboxylic acid copolymer or its ionomer, a polypropylene wax having a number average molecular weight of 50,000 or less, an ethylene / α-olefin copolymer having a number average molecular weight of 100,000 or more, a radical generator and a crosslinking aid. Modified polypropylene wax obtained by the above method.

The present invention also relates to a solar cell module using the above modified material as a solar cell element sealing material.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The sealing material of the present invention is for forming a solar cell module by sealing a solar cell element, an upper transparent protective material and a lower substrate protective material in a solar cell module.

The ethylene / unsaturated carboxylic acid copolymer or its ionomer as a 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. %, And has a melting point by DSC of 80 ° C. or more, preferably 85 to 105 ° C. Such a copolymer or its ionomer has an advantage that it has excellent transparency without using an ethylene copolymer having a high comonomer content as in the case of an ethylene / vinyl acetate copolymer.

Here, the unsaturated carboxylic acid includes acrylic acid, methacrylic acid, maleic acid, maleic anhydride and the like, and particularly preferred is acrylic acid or methacrylic acid. As the above-mentioned ethylene / unsaturated carboxylic acid copolymer, a copolymer obtained by copolymerizing a vinyl ester or a (meth) acrylic ester may be used because it is effective for imparting flexibility. Since those containing these copolymer components have low melting points, those containing a large amount cannot be used.

Examples of the ionomer of the ethylene / unsaturated carboxylic acid copolymer in the present invention include, as metal species, alkali metals such as lithium and sodium, and polyvalent metals such as calcium, magnesium, zinc and aluminum. be able to. The advantages of using such an ionomer are transparency and high storage modulus at high temperatures, and its neutralization degree is, for example, 80%.
Although it is desirable to use one having a degree of neutralization below, it is not advisable to use a substance having a very high degree of neutralization in consideration of adhesiveness and the like. For example, the degree of neutralization is 60% or less, particularly 30%
It is preferable to use the following.

When the above copolymer having an unsaturated carboxylic acid content of less than 4% by weight or an ionomer thereof is used, an excellent transparency cannot be obtained and the adhesiveness is also insufficient. Become. Further, when the content of unsaturated carboxylic acid increases, more excellent transparency can be obtained, but problems such as lowering of melting point and increase of hygroscopicity arise. In the present invention, since the melting point is specified to be 80 ° C. or higher, the content is naturally limited.

In the present invention, when a copolymer having a melting point lower than 80 ° C. is used as the above-mentioned copolymer or ionomer, it is difficult to obtain a modified product having sufficient heat resistance even if the modification described below is carried out. When used as an element sealing material, there is a risk of deformation due to a rise in temperature during use of the solar cell, and when the solar cell module is manufactured by the heat compression bonding method, these sealing materials flow out more than necessary and generate burrs. It is not preferable because of fear.

As the above copolymer or its ionomer, those having a melt flow rate (MFR) at 190 ° C. and a load of 2160 g of 0.1 to 500 g / 10 min, particularly 1 to 200 g / 10 min, are preferably used. preferable. When a material having a low MFR is used, a modified product having a low MFR can be obtained, and even if a material having a slightly lower melting point is used, there is an advantage that the above-described trouble due to the flow of the sealing material is unlikely to occur. On the other hand, if a material having a very low MFR is used, the workability deteriorates. On the other hand, if a material having an excessively high MFR is used, the MFR of the denatured product also increases, and the amount of the material protruding from the end portion and adhering to the laminate during module production increases. Gets worse.

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 content and MFR, and those having different metal species in the ionomer. To
Any two or more of them can be used in combination.

In the present invention, the above-mentioned ethylene / unsaturated carboxylic acid copolymer selected from (A), (B) and (C) or a modified ionomer thereof is used.

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. It is considered that the ionomer has a structure in which an oligoamide is grafted to a carboxyl group.

The nylon salt which can be used for the production of the modified product (A) is a salt of a diamine and a dicarboxylic acid, such as succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid and sebacin. Aliphatic dicarboxylic acids such as acids, alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid, aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid, and tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, octamethylenediamine , Decamethylenediamine,
Aliphatic diamines such as 2,4,4, -trimethylhexamethylenediamine, alicyclic diamines such as 1,3-bisaminomethylcyclohexane, 1,4-bisaminocyclohexane, bis (p-aminocyclohexyl) methane And salts with aromatic diamines such as 1,3-xylidenediamine.

Examples of the aminocarboxylic acids that can be used in the production of the modified product (A) include 6-aminohexanoic acid, 8-aminooctanoic acid, 10-aminodecanoic acid, 11-aminoundecanoic acid, and 12-aminododecanoic acid. Examples can be given.

In the process for producing the modified product (A), ethylene
Unsaturated carboxylic acid copolymer or ionomer 100
1 part by weight of nylon salt or aminocarboxylic acid
It is preferably used in a proportion of ４０40 parts by weight, especially 2-30 parts by weight.

The modified product (A) can be produced by kneading under a condition where the respective raw materials are melted, preferably at a temperature of 200 to 300 ° C., for example, using a kneading apparatus such as an extruder. As the modified product (A), it is desirable to use one having oligoamide units grafted in an amount of 0.5 to 40% by weight, particularly 1 to 30% by weight.
MFR at 2160 g load is 0.05 to 100
g / 10 minutes, particularly preferably 0.1 to 50 g / 10 minutes.

Although the reaction product obtained by melt-kneading may be used as it is as a solar cell encapsulating material, a purification operation such as extraction and removal of unreacted nylon salt or aminocarboxylic acid or the like may be used as necessary. May be used. An example of a method for producing such a modified product (A) is, for example, a method disclosed in Japanese Patent Application Laid-Open No. 10-287749.

The modified product (B) that can be used in the present invention is a modified ethylene 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 at least partially neutralized with a divalent metal cation, preferably a divalent transition metal cation.
That is, the ionomer neutralized with a transition metal cation easily forms an ammine complex salt by coordinating the terminal primary amino group of the polyamide oligomer to its carboxyl salt,
Further, it reacts with the carboxyl group to form an ammonium salt and binds to the polyamide oligomer. Thereby, a modified product excellent in transparency, heat resistance, and workability, which is suitable as a solar cell sealing material, can be easily obtained.

However, when only the transition metal ionomer is used, a modified product having good processability may not be obtained depending on the kind of the polyamide oligomer and its amount used. In this case, it is effective to replace, for example, half or less of the transition metal ionomer with an alkali metal ionomer. That is, the terminal primary amino group of the polyamide oligomer does not coordinate with the carboxyl salt of the alkali metal ionomer and thus does not form an ammine complex salt, and, depending on the degree of neutralization, reacts with the carboxyl group to form an ammonium salt and bond. However, the amount is smaller than that of the transition metal ionomer, so that the ionomer maintains its original processability, transparency, etc., and thus acts as an effective diluent.

The polyamide oligomer which can be used for the production of the modified product (B) has a primary amino group at one end or both ends and has a degree of polymerization of about 4 to 40.
If the degree of polymerization of the polyamide oligomer used is too large, it will be difficult to form a complex with the transition metal ionomer, and the effect of improving heat resistance will not be sufficient, and the transparency will decrease. Examples of polyamide oligomers include oligomers such as nylon 4, nylon 6, nylon 12, and nylon 610.

The amount of the polyamide oligomer used in the production of the modified product (B) is 1 to 30 parts by weight having a primary amino group at one end and 100 or less having primary amino groups at both ends per 100 parts by weight of the ionomer. Is about 1 to 15 parts by weight. If the polyamide oligomer having a primary amino group at one end is used in a large amount, unreacted substances may remain in a small amount, and transparency is impaired. If too much polyamide oligomer having a primary amino group at both ends is used, it becomes difficult to obtain a modified product having good processability.

The modified product (B) comprises an ionomer and a polyamide oligomer at a temperature not lower than the melting point of both, preferably 200 to 3
It can be obtained by kneading at a temperature of 00 ° C. Modified product (B) as a solar cell encapsulating material is 190
MFR at a load of 2160 g at 0.1 to 50 g /
Ten minutes is preferred.

The modified product (C) which can be used in the present invention includes the above-mentioned ethylene / unsaturated carboxylic acid copolymer or its ionomer, a polypropylene wax having a number average molecular weight of 50,000 or less, and a number average molecular weight of 100,000.
A modified polypropylene wax obtained by melt-kneading the above-mentioned ethylene / α-olefin copolymer, radical generator and crosslinking aid.

The above-mentioned polypropylene wax is a homopolymer of propylene or a copolymer of propylene with a small amount of another α-olefin such as ethylene, 1-butene, etc., and is directly produced by polymerization in the presence of a stereospecific catalyst. It is obtained by a method such as a method of producing a high-molecular-weight polypropylene obtained by polymerization in the presence of a stereospecific catalyst by thermal decomposition. Its number average molecular weight is 50,000 or less, preferably 100 to 35.
In order to obtain a modified product having excellent heat resistance, the melting point is preferably 120 ° C. or higher. Therefore, when using the above copolymer, α of the copolymer component
The olefin is present in an amount of not more than 10% by weight, in particular from 0.5 to 6% by weight;

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 a copolymer of ethylene having an ethylene content of preferably 5 to 50% by weight and an α-olefin having 3 or more carbon atoms. It is a copolymer composed of one or more kinds. When a copolymer having an ethylene content outside 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 above copolymer include propylene / ethylene copolymer, 1
-Butene / ethylene copolymer, 1-hexene / ethylene copolymer, 1-octene / ethylene copolymer, 1-decene / ethylene copolymer, and the like.

The radical generator used in the production of the modified product (C) is a compound having a molecule capable of generating a radical upon heating, such as an inorganic peroxide, an organic peroxide, a diazo compound or a disulfide compound. Can be mentioned. Particularly preferred are organic peroxides, for example,
Dicumyl peroxide, di-tert-butyl peroxide, 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane, 2,5-dimethyl-2,5-di (te
rt-butylperoxy) hexyne-3,1,3-bis (tert-butylperoxycyisopropyl) benzene,
1,1-bis (tert-butylperoxy) -3,3,5
-Trimethylcyclohexane, n-butyl-4,4-bis (tert-butylperoxy) valerate, benzoyl peroxide, p-chlorobenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, tert
-Butylperoxybenzoate, tert-butylperoxyisopropyl carbonate, diacetyl peroxide, lauroyl peroxide, tert-butylcumyl peroxide and the like.

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 a radical-scavenging ability, such as sulfur, metaphenylenebismaleimide, Examples thereof include quinone dioxime, 1,2-polybutadiene, triallyl cyanurate, diallyl phthalate, ethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, triethylene glycol dimethacrylate, triallyl isocyanurate and the like.

The proportion 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 its ionomer, 1 to 49 parts by weight of a polypropylene wax, and an ethylene / α-olefin copolymer. The proportion is such that the radical generator is 0.01 to 5 parts by weight and the crosslinking aid is 0.01 to 5 parts by weight based on 1 to 49 parts by weight and 100 parts by weight in total of these three components. If the amount of the radical generator or the 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) becomes poor and the appearance is good. It becomes difficult to obtain a suitable sealing material.

The modified product (C) is prepared by mixing the above components with a banbury mixer, a kneader, an extruder or the like.
It can be carried out by melt-kneading under such conditions that the various polymer components are melted and the radical generator is sufficiently decomposed. Suitable melt-kneading temperatures are at least 150 ° C, in particular in the range from 180 to 290 ° C. At this time, the ethylene / unsaturated carboxylic acid copolymer or its ionomer, the polypropylene wax and the ethylene / α-olefin copolymer may be mixed in advance, but when melt kneading in the presence of a radical generator, the other It is important that the components coexist, whereby a modified product having good heat resistance can be obtained. Even if the ethylene / unsaturated carboxylic acid copolymer or its ionomer and the polypropylene wax are melt-kneaded in the presence of a radical generator, a modified product having fluidity suitable for molding processing cannot be obtained, and the ethylene / unsaturated carboxylic acid Even if the copolymer or its ionomer and the ethylene / α-olefin copolymer are melt-kneaded in the presence of a radical generator, a modified product having excellent heat resistance cannot be obtained.

The modified product (C) thus obtained is granular,
It can be recovered in the form of a stick, flake, pellet, or the like. As the sealing material, MFR at 190 ° C. and 2160 g load is 0.1 to 3 in such a modified product.
It is preferable to use one having about 0 g / 10 minutes.

In the present invention, the above (A)
The modified product selected from (B) and (C) is used as a solar cell encapsulating material, but (A), (B) and (C) may be used alone or (A) And (B), (B) and (C), (C) and (A), or (A), (B) and (C). In addition, these modified products have a melting point of 80 ° C. or more, preferably 8 to improve processability and transparency.
An ethylene / unsaturated carboxylic acid copolymer at 5 to 105 ° C or an ionomer thereof may be blended and used. The allowable blending amount of the ethylene / unsaturated carboxylic acid copolymer or its ionomer varies depending on the type thereof, the degree of modification of (A), (B), and (C), but generally, the amount of the modified product is not limited. It is preferred to keep it below the weight.

Various additives can be added to the sealing material of the present invention, if necessary. When such additives are added to the encapsulant on the light-receiving side of the solar cell element, those that impair the transparency are not preferred, but are added to the encapsulant on the opposite side of the light-receiving side of the solar cell element. If so, there is no such restriction. Specific examples of such additives include antioxidants, light stabilizers, ultraviolet absorbers, coloring agents, light diffusing agents, flame retardants, discoloration inhibitors, silane coupling agents, and the like. Alternatively, an inorganic filler can be blended within a range that does not impair the transparency.

A solar cell module can be manufactured by using the sealing material of the present invention and fixing the solar cell elements with upper and lower protective materials. As such a solar cell module, various types can be exemplified. For example, a transparent protective material / encapsulating material / solar cell element / encapsulating material / lower protective material sandwiched between encapsulating materials from both sides of the solar cell element, formed on the inner peripheral surface of the lower substrate protecting material. A structure in which a sealing material and an upper transparent protective material are formed on a solar cell element that has been formed, and a sealing material and a lower protective material are formed on a solar cell element formed on the inner peripheral surface of the upper transparent protective material. And the like.

As the solar cell element, single crystal silicon,
Polycrystalline silicon, various solar cell elements such as silicon-based such as amorphous silicon, gallium-arsenic, copper-indium-selenium, III-V group and II-VI group compound semiconductor system such as cadmium-tellurium can be used, The sealing material of the present invention can be applied to sealing any of these solar cell elements.

Glass, acrylic resin, polycarbonate,
Examples include 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, and fluorine-containing. One-layer or multi-layer sheets of resin, polyolefin and the like can be exemplified. The sealing material of the present invention exhibits good adhesion to these upper or lower protective materials.

In manufacturing the solar cell module,
A module having the above-described configuration can be 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. In this case, since the sealing material does not contain an organic peroxide, sheet molding of the sealing material can be performed with high productivity at a high temperature, and it is not necessary to go through a two-stage 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 a solar cell element or an upper protective material or a lower protective material by extrusion coating the sealing material of the present invention is employed, a solar cell module can be manufactured in one step without forming a sheet. It is possible. Thus, by using the sealing material of the present invention, the productivity of the module can be remarkably improved.

When the sheet of the sealing material of the present invention is prepared in advance, a multilayer structure having an adhesive layer can be employed. That is, although the sealing material of the present invention has sufficient adhesiveness, a slight decrease in adhesive strength may be caused by various modifications. In this case, an adhesive layer having a thickness of about 5 to 100 μm can be provided on one or both of the upper and lower sides so as not to affect the storage elastic modulus in a high temperature range, and a decrease in adhesive strength can be suppressed. 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 the molding becomes difficult. The adhesive layer thickness is 100μ
When the thickness exceeds m, the elastic modulus in a high temperature range may be reduced. The adhesive layer used for such a purpose is not limited to the ethylene / unsaturated carboxylic acid copolymer or the ionomer used in the present invention, for example, a silane-modified olefin polymer or maleic anhydride. Use of an acid-modified product is also possible.

Whichever 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]

EXAMPLES The present invention will be described below in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples. In addition, the evaluation method of the raw materials and physical properties used in Examples and Comparative Examples is as follows.

1. Raw materials (1) Ethylene / unsaturated carboxylic acid copolymer and ionomer Ethylene / methacrylic acid copolymer (EMA shown in Table 1)
A) and its ionomer were used.

[0049]

[Table 1]

(2) Aminocarboxylic acid 12-aminododecanoic acid: manufactured by Ube Industries, Ltd. (3) Polyamide oligomer PAO (one end of ε-caprolactam oligomer having a degree of polymerization 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: 940)
0, manufactured by Mitsui Chemicals, Inc.) (5) Ethylene / α-olefin copolymer Ethylene / butylene / olefin crystal block copolymer (number average molecular weight 300,000) (6) Radical generator 2,5-dimethyl-2,5- Bis (tert-butylperoxy) hexine-3 (Atochem Yoshitomi Co., Ltd.) (7) Crosslinking aid Triallyl isocyanurate (Tokyo Chemical Industry Co., Ltd.)

2. Physical property evaluation method (1) Storage elastic modulus (E ') The storage elastic modulus was measured using the following device under the following conditions. Apparatus: DVE-V4 FT-Rheospectral made by Rheology Conditions: Tensile mode, frequency 10 Hz, amplitude 2 μm, sine wave, heating rate 3 ° C./min Measurement temperature 120 ° C., 140 ° C., 150 ° C. Press sheet sample thickness 2 mm

(2) Total light transmittance JIS K71 using a haze meter manufactured by Suga Test Instruments.
05. Press sheet sample thickness:
0.5mm

(3) Evaluation of Adhesion (A) vs. Glass A transparent glass plate as an upper transparent protective material for a solar cell and PE
0.5m created by the method described later between T-film
m is placed in a vacuum laminator with a press sheet having a thickness of m, placed on a hot plate adjusted to 160 ° C, and
Heating was performed for 5 minutes to produce a laminate of a glass plate / press sheet / PET film. About this laminated body, it peeled by hand between glass and a press sheet, observed the peeling condition, and evaluated by the following two steps. ○: good adhesion ×: poor adhesion

(B) Aluminum plate A 0.5 mm-thick press sheet prepared by a method to be described later is sandwiched between an aluminum plate and a PET film, and charged in a vacuum laminator. And heated for 15 minutes to form a laminate of aluminum plate / press sheet / PET film. About this laminated body, the aluminum sheet and the press sheet were peeled by hand, the degree of the peeling was observed, and the following two grades were evaluated. ○: good adhesion ×: poor adhesion

[Examples 1 to 3] Each raw material was blended at a blending ratio shown in Table 2, heated and kneaded with a small pressure kneader, and then subjected to press molding (molding temperature 160 ° C.) to a thickness of 0.5 mm and 2 mm. Created a sheet. Using these sheets, the storage elastic modulus, the total light transmittance, and the adhesiveness were evaluated by the methods (1) to (3) described above. Table 2 shows the results.

[Examples 4 and 5] An ionomer and a polyamide oligomer were compounded at a ratio shown in Table 2 and supplied to a single screw extruder (screw diameter: 30 mm, L / D = 32). The mixture was kneaded and extruded at an extrusion speed of 2 kg / h, and the strands coming out of the extruder were cut to obtain pellets of the modified polyamide oligomer.
Sheets having a thickness of 0.5 mm and 2 mm were formed from the pellets by press molding (molding temperature: 160 ° C.). Using these sheets, the storage elastic modulus, the total light transmittance, and the adhesiveness were evaluated by the methods (1) to (3) described above. Table 2 shows the results.

[Comparative Example 1] A press sheet was prepared using EMAA-2 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]

[Examples 6 to 8] Each raw material was blended at a blending ratio shown in Table 3, heated and kneaded with a small pressure kneader, and then subjected to press molding (molding temperature 160 ° C) to a thickness of 0.5 mm and 2 mm. Created a sheet. Using these sheets, the storage elastic modulus, the total light transmittance, and the adhesiveness were evaluated by the methods (1) to (3) described above. Table 3 shows the results.

[Comparative Example 2] A press sheet was prepared using EMAA-1 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]

As shown in Tables 2 and 3, the sealing material according to the present invention can be stored in a high temperature region without significantly impairing the transparency and adhesiveness as compared with the ethylene / unsaturated carboxylic acid copolymer alone. Excellent elastic modulus.

[0063]

The sealing material of the present invention does not require the use of a peroxide or a silane coupling agent for glass as an upper protective material, metal as a lower substrate protective material, a solar cell element, and the like. It shows excellent adhesiveness, and is also excellent in transparency and heat resistance. By using particularly suitable modifications, for example, the storage modulus at 150 ° C. is 1.
A sealing material having a light transmittance of 90% or more, preferably 91% or more can be easily obtained at a pressure of 0 × 10 ³ Pa or more, preferably 5.0 × 10 ³ Pa or more. Therefore, according to the present invention, even when the temperature rises during use of the solar cell module, it is possible to avoid a problem that the sealing material flows or deforms, and does not impair the appearance of the solar cell. Further, since the use of the above additives can be omitted, the productivity in the solar cell module manufacturing process can be significantly increased, and the manufacturing cost of the solar cell module can be significantly reduced.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08L 23/10 C08L 23/26 23/26 23/36 23/36 H01L 31/04 R H01L 23/29 23 / 30 R 23/31 31/02 B 31/02 F term (reference) 4J002 AC045 BB05X BB05Z BB08W BB09W BB12X BB12Y BB14X BB14Y BB23W BB28X EH077 EH147 EK016 EK036 EK046 EK086 ES017 A1A1A1A1A1A1A1A1A1A1A1A AE03 AF23 AF30 4M109 AA01 CA22 EA01 EC09 EC11 GA01 5F051 BA18 JA04 JA09 5F088 JA06

Claims (4)

[Claims] 1. 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 (A):
A solar cell element encapsulating material for a solar cell module, wherein a modified material selected from (B) and (C) is used. (A) An oligoamide-modified product obtained by melt-kneading the above-mentioned 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 above-mentioned ethylene / unsaturated carboxylic acid copolymer or its ionomer and a polyamide oligomer having a primary amino group at one or both terminals. (C) Melt kneading the above-mentioned ethylene / unsaturated carboxylic acid copolymer or its ionomer, a polypropylene wax having a number average molecular weight of 50,000 or less, an ethylene / α-olefin copolymer having a number average molecular weight of 100,000 or more, a radical generator and a crosslinking aid. Modified polypropylene wax obtained by the above method. 2. A modified product selected from (A), (B) and (C), wherein the content of unsaturated carboxylic acid is 4% by weight or more and the melting point of ethylene / unsaturated carboxylic acid copolymer is 80 ° C. or more. 2. The encapsulating material for a solar cell element according to claim 1, wherein the encapsulating material or an ionomer thereof is blended and used. 3. The storage elastic modulus at 150 ° C. is 10 ³ P
The solar cell element sealing material according to claim 1 or 2, wherein the total light transmittance is 90% or more. 4. A solar cell module using the solar cell element sealing material according to claim 1.