JP2011187822A - Filler composition for solar cell module, filler for solar cell module and solar cell module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyolefin-based filler composition for a solar cell module having physical properties demanded as a filler for a solar cell module, and high adhesion with a transparent front surface board, a rear surface protection sheet and a metal film. <P>SOLUTION: The filler used for a solar cell module has a composition including a copolymer made by copolymerizing α-olefin and ethylene-modified unsaturated silane compound while using them as co-monomers, and a silane coupling agent containing alkoxy groups and/or a silicone oligomer containing alkoxy groups. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a solar cell module filler, a solar cell module filler, and a solar cell module.

  In recent years, solar cells as a clean energy source have attracted attention due to the growing awareness of environmental issues. Currently, various types of solar cell modules have been developed and proposed.

  In general, a solar cell module has a configuration in which a transparent front substrate, a solar cell element, and a back surface protection sheet are laminated via a filler. And a solar cell element is the structure by which the surface electrode, the photoelectric converting layer, and the back surface electrode were laminated | stacked in order from the transparent front substrate side. The solar cell module has a function of generating electric power when sunlight enters the photoelectric conversion layer.

  In the solar cell module, high adhesion between the above-described layers is required. Therefore, high adhesion between the solar cell element and the filler is required. As an adhesion partner of the filler, not only adhesion to a substrate such as glass or film but also adhesion to an electrode disposed on the surface of the solar cell element is required. Here, for example, in a thin film type solar cell, a metal thin film such as an aluminum vapor deposition film or a silver vapor deposition film, or a transparent metal oxide thin film such as indium tin oxide or zinc oxide is formed on the element. Sex is also required.

  On the other hand, in addition to the adhesiveness to the back surface protective sheet and the adhesiveness to the front surface electrode and the back surface electrode, the filler has a strength to protect the solar cell element, and can withstand severe environments such as high temperature and high humidity. Heat resistance and moisture resistance are also required. As a material that satisfies these requirements, ethylene-vinyl acetate alcohol copolymer resin (EVA resin) is most commonly used.

  However, EVA resin has a tendency to gradually decompose with long-term use, and deteriorates inside the solar cell module to decrease its strength or generate acetic acid gas that affects the solar cell element. there is a possibility. Further, since EVA has a high water vapor permeability, there is a possibility that the adhesion with the above-described thin film may be particularly disturbed by moisture entering from the end face of the module.

  Then, the solar cell module filler which uses polyolefin, such as polyethylene, instead of EVA resin is proposed (for example, refer patent document 1 etc.). The filler using polyolefin described in Patent Document 1 and the like is an excellent filler having strength for protecting the solar cell element, heat resistance to withstand severe environments such as high temperature and high humidity, and moisture resistance. is there.

JP 2004-214641 A

  However, even when the polyolefin-based filler as described above is used, it cannot be said that the adhesion between the filler and the metal thin film or the metal oxide thin film (hereinafter also simply referred to as a metal film) is sufficient. It has been demanded.

  The present invention has been made in order to solve the above problems, and its purpose is to have physical properties required as a filler for a solar cell module and to have high adhesion to a transparent front substrate, a back surface protective sheet, and a metal film. An object of the present invention is to provide a polyolefin-based filler for solar cell modules having properties.

The inventors of the present invention have made extensive studies in order to solve the above problems, paying attention to the influence of a minute amount of moisture entering the interface between the filler and the metal film on the metal film.
As a result, a solar cell module comprising a copolymer obtained by copolymerizing an α-olefin and an ethylene-modified unsaturated silane compound as a comonomer, and an alkoxy group-containing silane coupling agent and / or an alkoxy group-containing silicone oligomer. The present inventors have found that the above problems can be solved by using the filler composition for use in the present invention, and have completed the present invention. More specifically, the present invention provides the following.

  (1) A solar cell module comprising a copolymer obtained by copolymerizing an α-olefin and an ethylene-modified unsaturated silane compound as a comonomer, and an alkoxy group-containing silane coupling agent and / or an alkoxy group-containing silicone oligomer. Filler composition.

  (2) The filler for solar cell modules according to (1), wherein the alkoxy group-containing silane coupling agent and / or the alkoxy group-containing silicone oligomer has at least one selected from a mercapto group, an epoxy group, and a triazine thiol group. Composition.

  (3) The filler composition for a solar cell module according to (1), wherein the alkoxy group-containing silane coupling agent has a mercapto group.

  (4) The filler composition for a solar cell module according to any one of (1) to (3), wherein the ethylene-modified unsaturated silane compound is an alkoxysilane having a vinyl group.

  (5) A solar cell module filler formed by molding the solar cell module filler composition according to any one of (1) to (4).

  (6) On the said back electrode of the solar cell element which has a laminated structure of 3 or more layers containing the structure by which a surface electrode, a photoelectric converting layer, and the back electrode which consists of metal films are arrange | positioned one by one as described in (5) A solar cell module in which a filler for a solar cell module is arranged.

  When the filler formed by molding the filler composition for solar cell modules of the present invention is used, even when a metal film is used as the back electrode of the solar cell module, the adhesion between the filler and the back electrode is improved. It is very high and has high adhesion to a back surface protection sheet such as glass and a transparent front substrate. Furthermore, the filler formed by molding the filler composition for solar cell modules of the present invention also has physical properties required for the filler for solar cell modules.

  Hereinafter, the filler composition for solar cell modules, the filler for solar cell modules, and the solar cell module of the present invention will be described in detail in this order.

<Filler composition for solar cell module>
The filler composition for a solar cell module of the present invention is a copolymer obtained by copolymerizing an α-olefin and an ethylene-modified unsaturated silane compound as a comonomer (hereinafter sometimes referred to as “silane copolymer”). And an alkoxy group-containing silane coupling agent and / or an alkoxy group-containing silicone oligomer. Hereinafter, after explaining these essential components, other resins and other components will be explained.

[Silane copolymer]
A silane copolymer is a component for improving adhesiveness with a transparent front substrate and a back surface protective sheet. When a silane copolymer is used, adhesion with glass is particularly improved.

  The silane copolymer is described in, for example, JP-A-2003-46105. By using the copolymer as a component of the solar cell module filler composition, it has excellent strength, durability, etc., and weather resistance, heat resistance, water resistance, light resistance, wind pressure resistance, yield resistance, It has excellent other characteristics, and has excellent heat-sealability without being affected by manufacturing conditions such as thermocompression bonding for manufacturing solar cell modules. It is stable, low-cost, and can be used in various applications. A suitable solar cell module can be manufactured.

  The silane copolymer is a copolymer obtained by copolymerizing at least an α-olefin and an ethylenically unsaturated silane compound as a comonomer and, if necessary, further using another unsaturated monomer as a comonomer. The modified product or condensate is also included.

Specifically, for example, one or more of α-olefins, one or more of ethylenically unsaturated silane compounds, and, if necessary, one or more of other unsaturated monomers. Using a desired reaction vessel, for example, pressure 500-4000 Kg / cm ² position, preferably, 1000-4000 Kg / cm ² position, temperature 100-400 ° C., preferably 150-350 ° C. In the presence of a radical polymerization initiator and, if necessary, a chain transfer agent, random copolymerization is performed simultaneously or stepwise, and if necessary, a random copolymer formed by the copolymerization is formed. A silane compound portion can be modified or condensed to produce a copolymer of an α-olefin and an ethylenically unsaturated silane compound, or a modified or condensed product thereof.

  Examples of the copolymer of an α-olefin and an ethylenically unsaturated silane compound or a modified or condensed product thereof include, for example, one or more α-olefins and, if necessary, other unsaturated monomers. One or two or more kinds are polymerized simultaneously or stepwise in the presence of a radical polymerization initiator and, if necessary, a chain transfer agent, using the desired reaction vessel, and then the polymerization. 1 to 2 or more types of ethylenically unsaturated silane compounds are graft-copolymerized to the polyolefin-based polymer produced by the above, and further, if necessary, a graft copolymer produced by the copolymer is constituted. A silane compound portion may be modified or condensed to produce a copolymer of an α-olefin and an ethylenically unsaturated silane compound or a modified or condensed product thereof. Kill.

  Usable α-olefins, ethylenically unsaturated silane compounds, other unsaturated monomers, radical polymerization initiators, chain transfer agents and the like are the same as those described in JP-A-2003-46105. It can be illustrated.

  Examples of the method of modifying or condensing the silane compound portion constituting the random copolymer, or the method of modifying or condensing the silane compound portion constituting the graft copolymer include, for example, tin, zinc, iron, lead, Using α-olefin and ethylenically unsaturated silane using metal carboxylate such as cobalt, organometallic compound such as titanate and chelate, organic base, inorganic acid, silanol condensation catalyst such as organic acid, etc. Modification of copolymer of α-olefin and ethylenically unsaturated silane compound by performing dehydration condensation reaction between silanols of the silane compound part constituting the random copolymer or graft copolymer with the compound The method of manufacturing a condensate is mentioned.

  As the silane copolymer used in the present invention, any of a random copolymer, an alternating copolymer, a block copolymer, and a graft copolymer can be preferably used. A graft copolymer is more preferable, and a graft copolymer obtained by polymerizing polyethylene for polymerization as a main chain and an ethylenically unsaturated silane compound as a side chain is more preferable. Since such a graft copolymer has a high degree of freedom of silanol groups that contribute to the adhesive force, the adhesiveness of the filler to other members (particularly glass) in the solar cell module can be improved.

  The content of the ethylenically unsaturated silane compound when constituting the copolymer of the α-olefin and the ethylenically unsaturated silane compound is, for example, about 0.001 to 15% by mass relative to the mass of the silane copolymer. Preferably, about 0.01 to 5% by mass, particularly preferably about 0.05 to 3% by mass is desirable. In the present invention, when the content of the ethylenically unsaturated silane compound constituting the copolymer of the α-olefin and the ethylenically unsaturated silane compound is large, the adhesiveness with the glass is excellent, but the content becomes excessive. , Tend to be inferior in tensile elongation and heat-fusibility.

[Other resins]
Resin other than the above-mentioned essential components can be contained in the filler composition for a solar cell module. By including an inexpensive resin in the solar cell module filler composition, a filler having excellent adhesion to metal and excellent adhesion to glass or the like can be obtained at low cost. As the resin for addition to the silane copolymer, a resin compatible with the silane copolymer is preferable, and specific examples thereof include an unmodified polyolefin resin such as polyethylene. More specifically, a polyethylene resin is preferable, and a low-density copolymer of ethylene and an α-olefin is preferably used from the viewpoint of imparting transparency. An example of such a resin is a metallocene linear low density polyethylene. The metallocene linear low density polyethylene is synthesized using a metallocene catalyst which is a single site catalyst. Such a polyethylene resin has few side chain branches and a uniform distribution of comonomer. For this reason, it can be set as the polyethylene-type resin with narrow molecular weight distribution and a small density, and can provide a softness | flexibility to a sheet | seat. From the viewpoint of transparency, a metallocene linear low-density polyethylene having a density in the range of 0.870 to 0.915 g / cm ³ is preferable, and the α-olefin has 6 to 8 carbon atoms. preferable. The amount of the resin for addition is preferably 50 to 95% by mass or less with respect to the silane copolymer. The unmodified polyolefin resin can also be used as a resin for previously mastering a “other component” described later.

  As a result, the content of the ethylenically unsaturated silane compound in the solar cell module filler composition of the present invention is, for example, about 1 to 80% by mass, preferably about 5 to 50% by mass, Most preferably, it is about 10-40 mass%.

[Silane coupling agent and / or silicone oligomer]
The silane coupling agent and / or the silicone oligomer is used for improving the adhesion between the metal film and the filler by using in combination with the silane copolymer. By using a silane coupling agent and a silicone oligomer among the materials that improve the adhesion to metal, there is no problem of gelation even when mixed with the silane polymer, and the filler for solar cell modules It is possible to achieve both high adhesion with glass and the like and high adhesion with the metal film while maintaining suitable physical properties. Even if the silane coupling agent and the silicone oligomer are used alone, the filler has high adhesion to the metal film, but the silane coupling agent and the like can be used together with the silane copolymer, Further improve the adhesion to the metal film.

  The silane coupling agent is an organosilicon compound having both an alkoxy group that is a hydrolyzable group that reacts with an inorganic substance and an organic functional group in one molecule. Silicone oligomer is an average degree of polymerization having both an alkoxy group, which is a hydrolyzable group that reacts with an inorganic substance, and an organic functional group by condensing two or more organosilicon compounds to form a —Si—O—Si— structure. Is a polymer of about 2 to 100.

  Examples of the organic functional group include an amino group, a mercapto group, an epoxy group, a methacryloxy group, and a triazine thiol group. Among these, in order to improve the adhesion between the filler and the metal film, a silane coupling agent having a mercapto group, an epoxy group or a triazine thiol group, or a silicone oligomer is preferable. In particular, a silane coupling agent having a mercapto group and a silicone oligomer are preferred.

  Preferable examples of the silane coupling agent include 3-glycidoxypropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropylmethyltrimethoxysilane, and the like.

  If the said silane coupling agent and a silicone oligomer are contained about 1000-10000 ppm or less by mass ratio in the filler composition for solar cell modules, adhesiveness with a metal can fully be improved.

  The silane coupling agent and silicone oligomer are preferably masterbatched in advance before mixing with the silane polymer or the like. As resin used for a masterbatch, a polyethylene-type resin is preferable. This is because a polyethylene resin is highly compatible with the silane polymer and other components described later. Specific examples include linear low density polyethylene and low density polyethylene. Polyethylene resins include not only ordinary polyethylene obtained by polymerizing ethylene, but also resins obtained by polymerizing compounds having ethylenically unsaturated bonds such as α-olefins, ethylenically unsaturated bonds. And a modified resin obtained by grafting another chemical species to these resins.

[Other ingredients]
The filler composition for a solar cell module can further contain other components. For example, a weather resistance masterbatch for imparting weather resistance to the filler prepared from the filler composition for solar cell modules of the present invention, various fillers, a light stabilizer, an ultraviolet absorber, a heat stabilizer, an antioxidant Ingredients such as agents are exemplified. By including these additives, it is possible to impart, to the solar cell module filler composition, a mechanical strength that is stable over a long period of time, an effect of preventing yellowing, cracking, and the like.

  A weatherproof masterbatch is a dispersion of a light stabilizer, ultraviolet absorber, heat stabilizer, antioxidant, etc., in a resin such as polyethylene, and this is added to the filler composition for solar cell modules. Thereby, favorable weather resistance can be provided to the filler for solar cell modules. The weatherproof masterbatch may be prepared and used as appropriate, or a commercially available product may be used. It does not specifically limit as resin used for a weatherproof masterbatch, Preferably a polyethylene-type resin is illustrated. Since the polyethylene resin is the same as that described above, the description thereof is omitted.

  These light stabilizers, ultraviolet absorbers, heat stabilizers and antioxidants can be used alone or in combination of two or more. In addition, the contents of the light stabilizer, the ultraviolet absorber, the heat stabilizer, and the antioxidant vary depending on the particle shape, density, etc., but 0.001 in the solar cell module filler composition, respectively. It is preferable to be within a range of ˜5 mass%.

  In addition to the above, other components used in the solar cell module filler composition of the present invention include nucleating agents, crosslinking agents, dispersing agents, leveling agents, plasticizers, antifoaming agents, flame retardants, and the like. Can do.

<Filler for solar cell module>
Next, the filler for solar cell modules of the present invention (“sometimes referred to as the filler of the present invention”) will be described. The solar cell module filler of the present invention is obtained by molding the above solar cell module filler composition by a conventionally known method, and is preferably in the form of a sheet or film. . In addition, the sheet form in this invention means the film form, and there is no difference in both.

  Sheeting or filming of the above-mentioned solar cell module filler composition is a molding method usually used in ordinary thermoplastic resins, that is, various molding methods such as injection molding, extrusion molding, hollow molding, compression molding, and rotational molding. Is done. Thus, the solar cell module filler of the present invention is obtained by forming the solar cell module filler composition into a sheet or film.

  The filling material formed into a sheet or film may not be a single layer. In order to improve the adhesion of the filler to the metal film and the glass, etc., a silane coupling agent and / or a silicone oligomer or silane copolymer should be present near the interface with the metal film or glass. That's fine. By making the silane coupling agent and / or the silicone oligomer or silane copolymer be present in the vicinity of the interface, the amount of expensive silane coupling agent used can be suppressed, and the filling of the present invention can be performed at a lower cost. The material can be manufactured. In particular, in the case of a thin film solar cell module, since the surface of the filler that contacts the back electrode is in contact with the transparent front substrate, the back electrode of the silane coupling agent and / or silicone oligomer or silane copolymer is used. The effect of being biased to the side is great.

  As a method for causing the silane coupling agent and / or the silicone oligomer or the silane copolymer to exist in the vicinity of the interface, for example, the structure of the solar cell module filler has a structure of three or more layers, that is, two sheets. Examples thereof include a method of forming a structure comprising a multilayer film having at least an outermost layer and a core layer sandwiched between the outermost layers. A silane coupling agent and / or a silicone oligomer or a silane copolymer is contained in the outermost layer that requires adhesion to the back electrode or the transparent front substrate, and the use amount of these is suppressed or not used in other layers. Thus, the effects of the present invention can be sufficiently obtained while suppressing the amount of these components used. Although the component contained in the outermost layer which adhere | attaches a core layer and a back surface protection sheet is not specifically limited, The above-mentioned silane copolymer, other resin, and another component can be contained preferably. In particular, since the outermost layer in close contact with the back surface protective sheet is required to have high adhesion with the back surface protective sheet made of glass or the like, it is preferable to contain a silane copolymer.

  In order to produce the solar cell module filler comprising the multilayer film as described above, for example, a conventionally known T-die multilayer coextrusion method can be used.

<Solar cell module>
As an example of the solar cell module using the solar cell module filler of the present invention, a thin film type solar cell module can be exemplified. A general thin-film solar cell module includes a solar cell element that is thinly laminated on a transparent front substrate such as glass or film from the incident light receiving surface side, and a back protective layer, also called a back sheet, that has a back filling layer. Are stacked. The solar cell element has a laminated structure of three or more layers including a configuration in which a transparent surface electrode, a photoelectric conversion layer, and a back electrode made of a metal film are sequentially arranged from the transparent substrate side. That is, the front surface side of the back surface filling layer is in close contact with the transparent front substrate and at the same time is in close contact with the back surface electrode of the solar cell element. For example, the solar cell module is formed by sequentially laminating the members forming the respective layers and then integrating them by vacuum suction or the like, and then thermocompression-bonding the respective layers as an integrally formed body by a molding method such as a lamination method. Can be manufactured.

  The solar cell module of the present invention uses the above-mentioned filler for solar cell module for the back filler layer. The solar cell module of the present invention is characterized in that the adhesion between the filler layer and the back electrode of the solar cell element and the adhesion between the back filler layer and the back protective sheet are both extremely high. Hereinafter, the solar cell element and the back surface protection sheet will be described.

The front electrode is, for example, transparent SnO ₂ , ZnO, ITO, etc., the photoelectric conversion element layer is, for example, single crystal silicon, polycrystalline silicon, amorphous silicon, etc., and the back electrode is, for example, aluminum, A film made of silver, gold or the like. Solar cell elements made of these materials can be manufactured by a conventionally known method.

  As a result of coexistence improvement of the base material and the metal film by the filler of the present invention, the back surface made of the above metal film as well as the glass as well as the matrix resin remains the hydrophobic olefin resin. It has become possible to improve the adhesion between the electrode and the filler. As a result, moisture ingress from between the filler on the module end face and the back electrode can be suppressed to the limit. For this reason, deterioration of the back electrode due to the presence of moisture can be suppressed for a long time.

  Examples of the deterioration include corrosion and ion migration. Since a weak current flows between the back electrode and the filler in the solar cell module, deterioration due to ion migration is considered to be a problem. Deterioration due to ion migration is particularly problematic in the case of metals that tend to be ions in water. Examples thereof include aluminum that is easily ionized in water, and silver that is unstable and ionizes due to an oxide generated by reaction with moisture. Even if the filler of this invention uses the above silver and aluminum as a back electrode, since a water | moisture content does not enter very easily between a filler and a back electrode, it can suppress deterioration of a back electrode.

  The filler of the present invention can also be preferably used for single-crystal and polycrystalline solar cell modules.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to a following example.

<Silane coupling agent, silicone oligomer>
Silane coupling agent 1: 3-glycidoxypropyltrimethoxysilane (trade name “KBM403”, manufactured by Shin-Etsu Chemical Co., Ltd.)
Silane coupling agent 2: 3-mercaptopropylmethyldimethoxysilane (trade name “KBM802”, manufactured by Shin-Etsu Chemical Co., Ltd.)
Silane coupling agent 3: 3-mercaptopropylmethyltrimethoxysilane (trade name “KBM803”, manufactured by Shin-Etsu Chemical Co., Ltd.)
Silicone oligomer: Triazine thiol group-containing (trade name “X24-9454”, manufactured by Shin-Etsu Chemical Co., Ltd.)

Said silane coupling agent and silicone oligomer were masterbatched by the following method.
97.5 parts by mass of powder obtained by pulverizing Ziegler linear low density polyethylene with a density of 0.901 g / cm ³ and 2.5 parts by mass of the silane coupling agent or silicone oligomer are mixed, melted, processed, and pelletized. A master batch was prepared (content of silane coupling agent and silicone oligomer in SI master batch was 5000 ppm). Hereinafter, this master batch is referred to as an Si master batch.

<Silane copolymer>
With respect to 98 parts by mass of a metallocene linear low density polyethylene having a density of 0.898 g / cm ³ and an MFR at 190 ° C. of 2 g / 10 minutes, 2 parts by mass of vinyltrimethoxysilane and a radical generator ( Dicumyl peroxide (0.1 part by mass) as a reaction catalyst) was mixed and melted and kneaded at 200 ° C. to obtain a silane copolymer. The density of this resin was 0.901 g / cm ³ , and the MFR at 190 ° C. was 1.0. Moreover, it adjusted so that an ethylenically unsaturated silane compound might be contained in 2.1 mass% to 2.8 mass% in a silane copolymer.

<Other resins>
As another resin, a metallocene linear low density polyethylene (hereinafter referred to as “LLDPE”) having a density of 0.901 g / cm ³ and an MFR at 190 ° C. of 2 g / 10 min was used.

<Other ingredients>
As other components, a weather-resistant masterbatch prepared by the following method was used.
With respect to 91.5 parts by mass of powder obtained by pulverizing Ziegler linear low-density polyethylene having a density of 0.924 g / cm ³ , 4.6 parts by mass of a hindered amine light stabilizer, 3.4 parts by mass of benzophenone, and phosphorous heat A weathering master batch was prepared by mixing and melting and processing 0.5 parts by mass of a stabilizer and pelletizing.

<Manufacture of solar cell filler composition>
In this example, in order to produce a solar cell filler having a three-layer structure, the following three types of solar cell filler compositions were prepared. Solar cell filler compositions 1 and 3 are outermost layers, and solar cell filler composition 2 is a core layer.
[Solar cell filler composition 1]
60 parts by mass of LLDPE, 20 parts by mass of an Si masterbatch, 20 parts by mass of a silane copolymer, and 5 parts by mass of a weatherproof masterbatch are mixed to obtain a filler composition 1 for a solar cell module. Obtained.

[Solar cell filler composition 2]
90 parts by mass of LLDPE, 10 parts by mass of a silane copolymer, and 5 parts by mass of a weather resistant master batch were mixed to obtain a filler composition 2 for a solar cell module.

[Solar cell filler composition 3]
80 parts by mass of LLDPE, 20 parts by mass of a silane copolymer, and 5 parts by mass of a weather resistant master batch were mixed to obtain a filler composition 3 for a solar cell module.

<Manufacture of solar cell module filler>
The filler for the solar cell module was prepared by a film forming machine having a T-die having a width of 2 m by extruding these compositions in three layers by a conventional method. The film formation temperature was set to 170 to 220 ° C. from the cylinder to the T die, and the temperature of the resin composition was 230 ° C. or lower. Note that the thickness ratio of the first layer, the second layer, and the third layer was 1: 5: 1, and the total thickness was 300 μm. Thus, the filler of the Example obtained in this way differs only in the kind of a silane coupling agent and a silicone oligomer as shown in Table 1.

Furthermore, in order to confirm the effect of this invention, the filler of the following comparative examples was produced.
[Comparative Example 1]
Instead of the solar cell filler composition 1, a solar cell module filler composition obtained by mixing 80 parts by mass of LLDPE, 20 parts by mass of an Si master batch, and 5 parts by mass of a weather resistant master batch. A filler of Comparative Example 1 was produced in the same manner as Example 2 except that it was used.
[Comparative Example 2]
Instead of the solar cell filler composition 1, a filler composition for a solar cell module obtained by mixing 80 parts by mass of LLDPE, 20 parts by mass of a silane copolymer, and 5 parts by mass of a weather resistant masterbatch. A filler of Comparative Example 2 was produced in the same manner as in Example except that was used.
[Comparative Example 3]
Instead of the solar cell filler composition 1, 55 parts by mass of LLDPE, 25 parts by mass of a modified polyolefin resin (trade name “Admer”) having high adhesion to the metal film, and 20 parts by mass of a silane copolymer, A filler of Comparative Example 3 was produced in the same manner as in Example except that a solar cell module filler composition obtained by mixing 5 parts by mass of a weatherproof masterbatch was used.

<Evaluation of physical properties of solar cell filler>
For these fillers, tensile strength, tensile elongation, water vapor permeability, volume resistivity, dielectric breakdown voltage, total light transmittance, and haze glass adhesion strength were measured. The measuring method is as follows, and Table 2 shows the results of the filler of Example 2 and these physical properties of fillers made of commonly used EVA resin.

Tensile strength (MPa) and tensile elongation (%) were measured according to JIS K-7127.
The water vapor permeability (g / {(m ² · 24h) · (300 µm)}) was measured according to the JIS K-7129 B method.
The volume resistivity (Ω · cm) was measured according to JIS K6911.
The dielectric breakdown voltage (kV / mm) measured the dielectric breakdown voltage (kV) per 1 mm thickness of the filler using a withstand voltage tester based on JIS C-2110. With regard to the breakdown voltage, when a sample having electrical insulation properties is sandwiched between two electrodes and then the voltage is gradually increased, the current increases rapidly, so that a part of the filler melts and holes are formed or carbonized. It shows the voltage when it becomes energized.
The total light transmittance (%) and haze were measured according to JIS K7105.
The glass adhesion strength (N / 15 mm width) is obtained by pressing the filler sheet with a 3 mm thick glass plate at 150 ° C. for 15 minutes using a vacuum laminator for manufacturing a solar cell module, and peel strength at 15 mm width according to JIS Z1707. (Unit: N / 15 mm) was measured. And evaluation of the adhesive strength with glass was performed also about the filler of Comparative Examples 1-3.

As described above, the filler of the present invention has physical properties equivalent to or better than EVA conventionally used as a filler for solar cell modules. In particular, the filler of the present invention has a very low water vapor permeability. In addition, it was confirmed that the fillers other than Example 2 also have physical properties equivalent to or higher than those of EVA as in Example 2.
Moreover, from the result of Comparative Example 1, it was confirmed that the adhesion to glass was not improved by using only the Si masterbatch containing a mercapto-based silane coupling agent. From the results of Comparative Example 3, it was confirmed that when the silane copolymer and Admer were used in combination, they were gelled during film formation and could not be produced as a film.

Furthermore, the adhesion between the fillers of Examples 1 to 4 and the filler of the comparative example and the silver deposited film was evaluated by the following method. For evaluation, a laminate formed by sequentially laminating 150 mm × 150 mm glass, 126 mm × 126 mm silver-deposited PET 12 μm, and a filler 300 μm was prepared by the following method.
In a vacuum laminator, the filler and the silver vapor deposited film were stacked and pressure-bonded at 150 ° C. for 15 minutes to produce a laminate. The laminate was stored in a constant temperature and humidity chamber at 85 ° C. and 85% for 7 days, then taken out, and the adhesion strength between the silver vapor deposition surface and the filler was evaluated. The evaluation results are shown in Table 3. The adhesion strength was measured by the same method as the glass adhesion strength.

  As is clear from the results in Table 3, it was confirmed that the filler of the present invention has very high adhesion to the silver deposited film. From the results of Examples 1 to 4 and Comparative Example 2, it was confirmed that the adhesion of the filler to the metal film was improved by containing the Si master batch. As is clear from the results of Example 2 and Comparative Example 1, it was confirmed that the adhesion between the silver deposited film and the filler was increased by using the silane copolymer and the Si master batch together. Moreover, although the filler of the comparative example 3 contains the admer which has high adhesiveness with a metal film, it gelled at the time of film-forming and the film was not able to be produced.

Furthermore, heat resistance and moisture resistance were evaluated by the following methods.
The heat resistance and moisture resistance of Example 3 were evaluated by comparing the filler of Example 2 with the following filler (reference example).
The filler (reference example) is a conventionally known olefin-based filler, which is a sun made by mixing 80 parts by mass of LLDPE, 20 parts by mass of a silane copolymer, and 5 parts by mass of a weather resistant masterbatch. The battery module filler composition was extruded as a single layer by a conventional method, and prepared to a thickness of 300 μm by a film forming machine having a 2 m wide T-die.
Evaluation was performed by the following method.
The filler sheet was pressed with a 3 mm thick glass plate at 150 ° C. for 15 minutes with a vacuum laminator for manufacturing a solar cell module, and the peel strength (unit: N / 15 mm) at a width of 15 mm was measured according to JIS Z1707 ( default value). Furthermore, when the laminate produced in the same manner was stored in 85 ° C. warm water for 66 hours, the peel strength was measured in the same manner when it was stored for 144 hours. The measurement results are shown in Table 4.
As is clear from the following results, it was confirmed that the product had the same strength as that of the conventional product (Reference Example 1) even under high temperature and high humidity. It was confirmed that the fillers other than Example 2 also have the same physical properties as the conventional product (Reference Example 1) as in Example 2.

Further, the contents of the silane coupling agent and the silicone oligomer were evaluated by the following methods. The following fillers were used for evaluation.
Filler of Example 3 Filler produced in the same manner as in Example 3 except that the content of the silane coupling agent in the Si masterbatch was changed to 2500 ppm (Reference Example 2)
A filler prepared in the same manner as in Example 3 except that the content of the silane coupling agent in the Si masterbatch was changed to 1250 ppm (Reference Example 3)
The evaluation was performed by the same method as the evaluation of adhesion with the silver deposited film. The evaluation results are shown in Table 5.

  It was confirmed that the adhesiveness between the filler and the silver deposited film was high even when the content (mass ratio) of the silane coupling agent or the like was very small.

Claims (6)

a copolymer obtained by copolymerizing an α-olefin and an ethylene-modified unsaturated silane compound as a comonomer;
The filler composition for solar cell modules containing an alkoxy group containing silane coupling agent and / or an alkoxy group containing silicone oligomer.   2. The solar cell module filler composition according to claim 1, wherein the alkoxy group-containing silane coupling agent and / or the alkoxy group-containing silicone oligomer has at least one selected from a mercapto group, an epoxy group, and a triazine thiol group.   The filler composition for a solar cell module according to claim 1 or 2, wherein the alkoxy group-containing silicone oligomer has a triazine thiol group.   The filler composition for a solar cell module according to any one of claims 1 to 3, wherein the ethylene-modified unsaturated silane compound is an alkoxysilane having a vinyl group.   The filler for solar cell modules formed by shape | molding the filler composition for solar cell modules in any one of Claim 1 to 4.   6. The solar cell module according to claim 5, wherein the solar cell module according to claim 5 is provided on the back electrode of a solar cell element having a laminated structure of three or more layers including a configuration in which a front electrode, a photoelectric conversion layer, and a back electrode made of a metal film are sequentially arranged. Solar cell module in which a filler is disposed.