WO2021145427A1 - Sealing material sheet for solar cell module, multi-layer sealing material sheet for solar cell module, sealing material composition for solar cell module, solar cell module, and method for manufacturing sealing material sheet for solar cell module - Google Patents

Abstract

Provided are sealing material sheets for a solar cell module (2, 3), the sealing material sheets for a solar cell module (2, 3) characterized by using a polyethylene-based resin as the base resin, by containing an organic peroxide that is a crosslinking agent, a nurate-ring-containing compound that is a crosslinking aid and that has two or more polymerizable reactive groups in one molecule, and a silane coupling agent, and by being uncrosslinked sealing material sheets (2, 3) in which the content of the crosslinking agent in the sealing material sheets (2, 3) is 0.33-0.53 mass% inclusive, the content of the crosslinking aid is 0.30-0.90 mass% inclusive, and the content of the silane coupling agent is 0.15-0.40 mass% inclusive.

Description

Method for manufacturing encapsulant sheet for solar cell module, multi-layer encapsulant sheet for solar cell module, encapsulant composition for solar cell module, solar cell module, and encapsulant sheet for solar cell module

The present disclosure relates to a sealing material sheet for a solar cell module, a multi-layer sealing material sheet for a solar cell module, a sealing material composition for a solar cell module, and a solar cell module using these.

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

As a sealing material sheet for a solar cell module, a resin based on EVA (ethylene-vinyl acetate copolymer) having excellent transparency, adhesion, etc. is widely used (Patent Document 1). However, in recent years, development of a sealing material sheet for a solar cell module based on a polyethylene-based resin having transparency equivalent to that of EVA and superior in hydrolysis resistance and the like as compared with EVA has been progressing.

Japanese Unexamined Patent Publication No. 2009-135200

A thermosetting encapsulant sheet containing such a polyethylene-based resin as a base resin and containing a cross-linking agent may cause bleed-out of additives to the sheet surface or outgas during manufacturing of a solar cell module. there were.

The present disclosure is an invention made in view of the above circumstances, and an object of the present disclosure is to provide a sealing material sheet for a solar cell module capable of manufacturing a highly reliable solar cell module.

In order to solve the above problems, the present inventors used a polyethylene-based resin as a base resin, and set the content of a specific cross-linking agent, a specific cross-linking aid, and a silane coupling agent within a specific range. We have found that a highly reliable solar power module can be manufactured if it is a sealing material sheet, and have completed the present invention.

That is, the present disclosure is a sealing material sheet for a solar cell module, which uses a polyethylene resin as a base resin, and polymerizes two or more in one molecule which is a cross-linking agent and an organic peroxide which is a cross-linking agent. The content of the cross-linking agent in the encapsulant sheet is 0.33% by mass or more and 0.53% by mass or less, and the cross-linking is contained, and contains a nurate ring-containing compound having a sex reactive group and a silane coupling agent. Encapsulant for solar cell module, the content of auxiliary agent is 0.30% by mass or more and 0.90% by mass or less, and the content of the above-mentioned silane coupling agent is 0.15% by mass or more and 0.40% by mass or less. Provide a sheet.

Further, the present disclosure is a multilayer encapsulant sheet for a solar cell module having a core layer and skin layers arranged on both sides of the core layer, and the core layer is thicker than the skin layer. The skin layer is silane coupling with an organic peroxide which is a cross-linking agent and a nurate ring-containing compound having two or more polymerizable reactive groups in one molecule which is a cross-linking aid, using a polyethylene resin as a base resin. The content of the cross-linking agent in the skin layer is 0.33% by mass or more and 0.53% by mass or less, and the content of the cross-linking aid is 0.30% by mass or more and 0.90% by mass. % Or less, and the content of the silane coupling agent is 0.15% by mass or more and 0.40% by mass or less, providing a multilayer encapsulant sheet for a solar cell module.

Further, the present disclosure is a sealing material composition for a solar cell module, which uses a polyethylene resin as a base resin, an organic peroxide as a cross-linking agent, and two or more in one molecule as a cross-linking aid. A nurate ring-containing compound having a polymerizable reactive group and a silane coupling agent are contained, and the content of the cross-linking agent in the encapsulant composition is 0.33% by mass or more and 0.53% by mass or less. Seal for solar cell module, the content of the cross-linking aid is 0.30% by mass or more and 0.90% by mass or less, and the content of the silane coupling agent is 0.15% by mass or more and 0.40% by mass or less. A stop material composition is provided.

The present disclosure discloses a solar cell element, a front surface side protective member, a back surface side protective member, the above-mentioned sealing material sheet for a solar cell module, the above-mentioned multi-layer sealing material sheet for a solar cell module, and the above-mentioned solar cell module. A sealing material containing a sealing material layer which is a crosslinked product of any of the sealing material compositions for use, and the solar cell element is arranged between the front surface side protective member and the back surface side protective member. Provided is a solar cell module sealed by a layer.

Further, the present disclosure is a method for producing a sealing material sheet for a solar cell module, which comprises a polyethylene-based resin and a nurate ring-containing compound having two or more polymerizable reactive groups in one molecule as a cross-linking aid. To obtain a mixture, a step of mixing the above mixture, an organic peroxide as a cross-linking agent, and a silane coupling agent to obtain a sealing material composition, and the above-mentioned sealing material composition. It has a step of melting and forming a film into a sheet to obtain an uncrosslinked encapsulant sheet, and the content of the crosslinking agent in the encapsulant sheet is 0.33% by mass or more. 53% by mass or less, the content of the cross-linking aid is 0.30% by mass or more and 0.90% by mass or less, and the content of the silane coupling agent is 0.15% by mass or more and 0.40% by mass or less. Provided is a method for manufacturing a sealing material sheet for a solar cell module.

The encapsulant sheet for a solar cell module disclosed in the present disclosure has an effect that a highly reliable solar cell module can be manufactured.

It is the schematic cross-sectional view which illustrates the solar cell module of this disclosure. It is schematic cross-sectional view which illustrates the multilayer sealing material sheet using the sealing material sheet for a solar cell module of this disclosure.

An embodiment of the present disclosure will be described below with reference to drawings and the like. However, the present disclosure can be implemented in many different embodiments and is not construed as limited to the description of the embodiments illustrated below. In addition, in order to clarify the explanation, the drawings may schematically represent the width, thickness, shape, etc. of each part as compared with the actual form, but this is just an example and the interpretation of the present disclosure is limited. It's not something to do. Further, in the present specification and each figure, the same elements as those described above with respect to the above-mentioned figures may be designated by the same reference numerals, and detailed description thereof may be omitted as appropriate.

When writing "above" or "below", unless otherwise specified, when another member is placed directly above or directly below a certain member, and above or below a certain member, unless otherwise specified. Including the case where another member is arranged via yet another member.

Further, in the present specification, terms such as "sheet", "film", and "board" are not distinguished from each other based only on the difference in names. For example, "sheet" is used to include a member that is also called a film or a plate.

In the present specification, the encapsulant sheet for a solar cell module is also simply referred to as an encapsulant sheet, and the encapsulant composition for a solar cell module is also simply referred to as an encapsulant composition.

As described above, the development of a thermosetting encapsulant sheet using a polyethylene resin having excellent hydrolysis resistance as a base resin is in progress. In general, polyethylene is less likely to undergo a cross-linking reaction than EVA, and it is necessary to allow the cross-linking reaction to proceed to a extent sufficient to secure the required heat resistance. Further, in order to suppress connection failure due to expansion and contraction of wiring, it has been required to increase the elastic modulus of the encapsulant layer of the solar cell module. Therefore, a large amount of a cross-linking agent and a cross-linking aid for increasing the gel fraction are usually added to the thermosetting encapsulant sheet using the polyethylene resin as the base resin.

However, due to the excessive addition of the cross-linking agent, the present inventors generated outgas due to the cross-linking agent during the integration process as the solar cell module, the durability test, etc., and the generated gas was sufficiently generated. It was found that by staying inside the solar cell module without being degassed, it remains as bubbles and hinders power generation. In addition, although the specific cross-linking aid has the effect of improving the gel fraction, the present inventors, especially when a polyethylene-based resin is used as the base resin, bleed-out occurs when the content of the cross-linking aid is large. It has been found that there is a possibility that problems such as deterioration of workability and hindering adhesion with other members may occur, and the reliability of the solar cell module is lowered.

Therefore, we tried to reduce the content of the cross-linking agent and the cross-linking aid in the sealing material sheet, but the amount of the silane coupling agent added to ensure the adhesion to the glass, cells, wiring, etc. If the amount is excessive, the amount of the silane coupling agent that captures the radicals when cross-linking the polyethylene resin becomes large, and as a result, the degree of cross-linking decreases and the gel fraction cannot be increased. It was found that there are cases.

Therefore, the present inventors use a polyethylene-based resin as the base resin, and use a sealing material sheet containing a specific cross-linking agent, a specific cross-linking aid, and a silane coupling agent within a specific range. If there is, it is possible to suppress the bleeding of additives and the generation of outgas during the manufacture of solar cell modules, and the highly reliable sun that satisfies the required characteristics such as high adhesion to glass and high gel fraction. We have found that it is a sealing material sheet that can be used to manufacture electric modules.

Hereinafter, a method for manufacturing a sealing material sheet for a solar cell module, a multilayer sealing material sheet for a solar cell module, a sealing material composition for a solar cell module, a solar cell module, and a sealing material sheet for a solar cell module of the present disclosure. The details of.

A. Encapsulant sheet for solar cell module The encapsulant sheet for solar cell module of the present disclosure uses a polyethylene resin as a base resin, and contains two or more organic peroxides as a cross-linking agent and one molecule as a cross-linking aid. The content of the cross-linking agent in the encapsulant sheet is 0.33% by mass or more and 0.53% by mass or less. The content of the cross-linking aid is 0.30% by mass or more and 0.90% by mass or less, and the content of the silane coupling agent is 0.15% by mass or more and 0.40% by mass or less.

By setting the content of the above-mentioned cross-linking agent within the above-mentioned range, the encapsulant sheet of the present disclosure can generate outgas due to the cross-linking agent during the integration process as a solar cell module, the durability test, and the like. It can be suppressed and bubbles are less likely to be generated inside the solar cell module. Further, by setting the content of the above-mentioned cross-linking aid within the above range, bleeding of the above-mentioned cross-linking aid can be suppressed, and problems such as hindering adhesion to other members are less likely to occur. .. Furthermore, by setting the content of the silane coupling agent within the above range, it is possible to suppress a decrease in the crosslink density without causing a problem in adhesion to other members such as a glass substrate. Become. Therefore, the bleeding of the cross-linking aid and the generation of outgas during the manufacture of the solar cell module can be suppressed, and the highly reliable sun that satisfies the required characteristics such as high adhesion to glass and high gel fraction. It is a sealing material sheet that can manufacture electric modules.

1. 1. Composition of Encapsulant Sheet The encapsulant sheet of the present disclosure uses a polyethylene resin as a base resin, and the content of organic peroxide as a cross-linking agent in the encapsulant sheet is 0.33% by mass or more. 53% by mass or less, the content of the nurate ring-containing compound having 2 or more polymerizable reactive groups in one molecule of the cross-linking aid is 0.30% by mass or more and 0.90% by mass or less, and the content of the silane coupling agent is contained. The amount is 0.15% by mass or more and 0.40% by mass or less. Each content can be determined by the method described in "2. Method for measuring the content of each component in the encapsulant sheet" described later.

(1) Polyethylene-based resin The sealing material sheet for a solar cell module of the present disclosure contains a polyethylene-based resin as a base resin. In addition, in this specification, a "base resin" means a resin having the largest content ratio in the resin composition in the resin composition containing the base resin.

As the encapsulant sheet used for the solar cell module, a resin sheet made of ethylene-vinyl acetate copolymer resin (EVA) is generally used. However, EVA resin tends to be gradually decomposed with long-term use, and deteriorates inside the solar cell module to reduce its strength or generate acetic acid gas that affects the solar cell element. there is a possibility. In the present disclosure, since a polyethylene-based resin is used as the base resin, such a problem does not occur.

The polyethylene-based resin used in the present disclosure includes not only ordinary polyethylene obtained by polymerizing ethylene, but also a copolymer of ethylene and α-olefin. The α-olefin is preferably an α-olefin having 3 to 12 carbon atoms. Specifically, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-hepten, 4-methyl-pentene-1, 4-methyl-hexene-1, 4,4-dimethylpentene- The first prize can be mentioned. Specific examples of the ethylene / α-olefin copolymer include an ethylene / propylene copolymer, an ethylene / 1-butene copolymer, an ethylene / 1-hexene copolymer, an ethylene / 1-octene copolymer, and an ethylene / α-olefin copolymer. Examples thereof include 4-methyl-pentene-1 copolymer. In the present disclosure, an ethylene / propylene copolymer is particularly preferable. Further, the α-olefin may be one kind or a combination of two or more kinds.

Among them, low-density polyethylene-based resin (LDPE) and linear low-density polyethylene-based resin (LLDPE) can be preferably used.

In this disclosure, 0.870 g / cm ³ or more 0.920 g / cm ³ or less, especially, 0.880 g / cm ³ or more 0.890 g / cm ³ or less of low density polyethylene, among others, linear low density polyethylene (LLDPE ) Is preferably used. By using low-density polyethylene as the base resin as described above, the transparency of the encapsulant sheet can be improved, and the flexibility can be improved. The risk of cracking can also be reduced.

Further, the polyethylene-based resin in the present disclosure has an MFR value at 190 ° C. and a load of 2.16 kg measured in accordance with JIS K7210 from the viewpoint of maintaining good film-forming property (“MFR” in the present specification is referred to as “MFR”. The value measured under these conditions is preferably 3.0 g / 10 min or more and 30.0 g / 10 min or less, and more preferably 10 g / 10 min or more and 25 g / 10 min or less.

In particular, in the present disclosure, a polyethylene resin that is easily crosslinked by a crosslinking agent and a crosslinking aid described later is preferable. Examples of such a polyethylene-based resin include a polyethylene-based resin having a reactive functional group in the side chain or the end. Examples of the reactive functional group include unsaturated bond-containing groups, and examples thereof include vinyl, vinylidene, cis-vinylene, trans-vinylene, and trisubstituted-vinylene. Further, as the polyethylene-based resin (ethylene / α-olefin copolymer) in the present disclosure, the total amount of vinyl, vinylidene, cis-vinylene, trans-vinylene, and trisubstituted-vinylene is 0.22 (pieces / total 1000C). The above is preferable. Here, the number of vinyl, vinylidene, cis-vinylene, trans-vinylene, and trisubstituted-vinylene is the number per 1000 carbon atoms in total of the main chain and the side chain measured by NMR. The total amount of vinyl, vinylidene, cis-vinylene, trans-vinylene, and trisubstituted-vinylene in the ethylene / α-olefin copolymer is more preferably 0.25 or more, particularly preferably 0.30 or more, and 0.40. The above is more preferable, and 0.50 or more is particularly preferable. Specifically, the polyethylene-based resin described in JP-A-2014-168901 can be used.

The content of the polyethylene-based resin with respect to the total resin components of the encapsulant sheet is preferably 90% by mass or more, more preferably 95% by mass or more, when the mass of the encapsulant sheet is 100% by mass. As a result, the sealing material has an excellent balance of transparency, adhesiveness, heat resistance, flexibility, appearance, cross-linking characteristics, electrical characteristics, and the like.

(2) Cross-linking agent The sealing material sheet of the present disclosure contains an organic peroxide as a cross-linking agent. Organic peroxides are compounds that have at least an OO bond with a carbon atom. The content of the organic peroxide in the present disclosure is 0.33% by mass or more and 0.53% by mass or less, preferably 0.38% by mass, when the whole encapsulant sheet is 100% by mass. % Or more and 0.50% by mass or less, more preferably 0.42% by mass or more and 0.48% by mass or less. When the content of the cross-linking agent is less than the above lower limit, the cross-linking density is lowered and the gel fraction is lowered. On the other hand, if it exceeds the above upper limit value, outgas, which is a decomposition product of organic peroxide, is generated during the integration process as a solar cell module or during the durability test, which causes bubbles and is reliable. Unable to manufacture expensive solar cell modules.

In the present disclosure, the organic peroxide as the cross-linking agent preferably has a molecular weight of 200 or more and 350 or less, and more preferably 220 or more and 300 or less. With the organic peroxide having the above molecular weight, it is possible to generate an amount of radicals that sufficiently secures a cross-linking point, and it is possible to reliably suppress outgas, which is a decomposition product of the organic peroxide. Is preferable.

Further, among the organic peroxides within the above molecular weight range, those having a one-hour half-life temperature of 110 ° C. or higher and 145 ° C. or lower are preferable. Here, the half-life of the organic peroxide is the time until the organic peroxide is decomposed by heat and the amount of active oxygen thereof is halved from the amount before decomposition. When the 1-hour half-life temperature is at least the above lower limit value, it is preferable because it is possible to prevent cross-linking from occurring during film formation. Further, if it is equal to or less than the above upper limit value, radicals can be reliably generated during the module integration step, which is preferable.

Further, it is preferable that the amount of active oxygen of the organic peroxide is in the range of about 5.0% to about 10.0%. When the amount of active oxygen is equal to or higher than the above lower limit, a sufficient amount of radicals required for cross-linking the polyethylene resin and the cross-linking aid can be sufficiently generated, and the encapsulant is surely cross-linked during the module integration process. It is preferable to do so.

In the present disclosure, examples of the organic peroxide as a cross-linking agent include peroxycarbonates such as t-amyl-peroxy-2-ethylhexyl carbonate and t-butylperoxy2-ethylhexyl carbonate, and n-butyl. Peroxyketals such as 4,4-di (t-butylperoxy) valerate, ethyl 3,3-di (t-butylperoxy) butane, 2,2-di (t-butylperoxy) butane, di -T-Butyl peroxide, t-Butyl cumyl peroxide, Dicumyl peroxide, 2,5-dimethyl-2,5-di (t-butyl peroxy) hexane, 2,5-dimethyl-2,5-di Dialkyl peroxides such as (t-peroxy) hexin-3 can be mentioned as a cross-linking agent that can be used by adding it to the encapsulant composition. In the present disclosure, the above-mentioned cross-linking agent may be used alone or in combination of two or more.

In particular, in the present disclosure, the cross-linking agent is t-butylperoxy2-ethylhexyl carbonate (product name "Luperox TBEC") from the viewpoint of having good reactivity with the polyethylene resin as the base resin. Alchema Yoshitomi Co., Ltd.) is preferable.

(3) Crosslinking Aid The encapsulant of the present disclosure contains a nurate ring-containing compound having two or more polymerizable reactive groups in one molecule as a crosslinking aid. The content of the nurate ring-containing compound in the present disclosure is 0.30% by mass or more and 0.90% by mass or less, preferably 0.45% by mass, when the whole encapsulant sheet is 100% by mass. % Or more and 0.78% by mass or less, more preferably 0.50% by mass or more and 0.70% by mass or less.

The cross-linking aid used in the present disclosure is preferably a nurate ring-containing compound from the viewpoint of improving reactivity, but the nurate ring-containing compound has poor compatibility with the polyethylene resin and is prone to bleed-out. Become. Therefore, the above upper limit value is set to prevent a problem due to bleeding out. On the other hand, if the content of the cross-linking aid is less than the above lower limit, the gel fraction after the cross-linking treatment of the encapsulant sheet decreases, which is not preferable.

The cross-linking aid in the present disclosure may be a nulate ring-containing compound having two or more polymerizable reactive groups in one molecule, and the preferred number of polymerization reactive groups is 2 to 6 in one molecule. It is preferable, and particularly preferably 2 to 3 pieces. This is because if it is smaller than the above range, the crosslink density may not be sufficiently increased. On the other hand, if it is larger than the above range, the physical properties of the sealing layer may be adversely affected, such as the sealing layer after the cross-linking treatment becoming brittle.

The polymerizable reactive group contained in the cross-linking agent in the present disclosure is not particularly limited as long as it can react with the polyethylene-based resin which is the base resin and impart a cross-linked structure. In the present disclosure, a group having a carbon-carbon double bond such as a vinyl group, a (meth) acryloyl group, a (meth) acryloyloxy group, and an allyl group, an epoxy group, and the like are preferable.

Specific examples of the cross-linking aid in the present disclosure include polyallyl compounds such as triallyl isocyanurate (TAIC), triallyl cyanurate, diallyl phthalate, diallyl fumarate, and diallyl maleate, and trimethylolpropane trimethacrylate (TMPT). , Trimethylolpropane triacrylate (TMPTA), ethylene glycol diacrylate, ethylene glycol dimethacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, 1,9-nonanediol diacrylate and other polys ( Meta) Acryloxy compounds, glycidyl methacrylates containing double bonds and epoxy groups, 4-hydroxybutyl acrylate glycidyl ethers and 1,6-hexanediol diglycidyl ethers containing two or more epoxy groups, 1,4-butanediol diglycidyl. Examples thereof include epoxy compounds such as ether, cyclohexanedimethanol diglycidyl ether, and trimethylolpropane polyglycidyl ether. These may be used alone or in combination of two or more. In addition, among the above-mentioned cross-linking aids, it also contributes remarkably to the improvement of glass adhesion of the sealing material, has good compatibility with linear low-density polyethylene, lowers crystallinity by cross-linking, maintains transparency, and has a low temperature. TAIC can be preferably used from the viewpoint of imparting flexibility in the above.

(4) Silane Coupling Agent The encapsulant sheet of the present disclosure contains a silane coupling agent. The content of the silane coupling agent in the present disclosure is 0.15% by mass or more and 0.40% by mass or less, preferably 0.17% by mass, when the total content of the encapsulant sheet is 100% by mass. % Or more and 0.35% by mass or less, more preferably 0.20% by mass or more and 0.30% by mass or less. If the content of the silane coupling agent in the encapsulant sheet is less than the above lower limit value, the adhesion to glass, cells, wiring and the like is lowered. On the other hand, if it is more than the above upper limit value, the amount of radicals generated when the cross-linking reaction is carried out on the polyethylene resin by using the above-mentioned cross-linking agent or the like is increased by the above-mentioned silane coupling agent, which is sufficient. This is because it may not be possible to obtain the crosslink density.

As the silane coupling agent in the present disclosure, for example, a methacryoxy-based silane coupling agent, an acryloxy-based silane coupling agent, an epoxy-based silane coupling agent, or a mercapto-based silane coupling agent can be preferably used. Of these, acryloxy-based or methacryloxy-based silane coupling agents are preferable, and specifically, 3-acryloxypropyltrimethoxysilane, 3-acryloxypropyltriethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxy. Examples thereof include propyltriethoxysilane, 3-acryloxypropylmethyldimethoxysilane, 3-acryloxypropylmethyldiethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, and 3-methacryloxypropylmethyldiethoxysilane. The methacryloxy-based and acryloxy-based silane coupling agents are not particularly limited, and known silane coupling agents can be preferably used. For example, there are "KBM503" and "KBM-5103" (both manufactured by "Shinetsu Silicone Co., Ltd."), which are easily available from the market. In the present disclosure, those having a (meth) acryloyloxy group are preferable, and 3-methacryloxypropyltrimethoxysilane is particularly preferable.

(5) Other Additives The encapsulant sheet of the present disclosure may contain other additives other than the above-mentioned polyethylene resin, cross-linking agent, cross-linking aid and silane coupling agent. As other additives, weather resistant agents, UV absorbers, antioxidants, heat stabilizers, nucleating agents, dispersants, leveling agents, plasticizers, defoamers, flame retardants, and various other fillers are appropriately added. be able to.

Examples of the weather resistant agent include hindered amine-based light stabilizers (HALS). Hindered amine-based photostabilizers are roughly classified according to the bond partner of the nitrogen atom in the piperidine skeleton, and are classified into NH type (hydrogen is bonded to the nitrogen atom), NR type (alkyl group (R) is bonded to the nitrogen atom), and There are three types of N-OR type (an alkoxy group (OR) is bonded to a nitrogen atom), and among these, an N-OR type hindered amine-based light-resistant stabilizer can be particularly preferably used. Examples of the N-OR type hindered amine-based light-resistant stabilizer include Tinuvin NOR 371 and Tinuvin XT850 (manufactured by BASF Japan Ltd.). The N-OR type has a faster rate of capturing radicals than the NH type and the N-R type. Furthermore low-molecular HALS of N-OR type having transferred to the faster surface than polymeric HALS is short term supplemented radicals than N-H-type or N-CH ₃ type HALS, suppress the deterioration of the sealing sheet In that respect, it is preferable.

As the ultraviolet absorber, antioxidant, heat stabilizer, nucleating agent, dispersant, leveling agent, plasticizer, defoaming agent, flame retardant, and various other fillers, conventionally known ones can be used.

In the present disclosure, the above-mentioned weather resistant agent, ultraviolet absorber, antioxidant and the like are added to the sealing material composition as a weather resistant masterbatch in which a resin such as polyethylene is dispersed, thereby forming a sealing material sheet. Good light resistance can be imparted. The weather-resistant masterbatch may be appropriately prepared and used, or a commercially available product may be used. The resin used in the weatherproof masterbatch may be polyethylene in the present disclosure or other resin.

2. Method for Measuring the Content of Each Component in the Encapsulant Sheet As described above, the encapsulant sheet of the present disclosure keeps the contents of the above-mentioned cross-linking agent, the above-mentioned cross-linking aid, and the silane coupling agent within the above range. It is characterized by doing. The method for measuring these contents is not particularly limited, but can be determined by, for example, infrared spectroscopy, gas chromatography-mass spectrometry, or the like.

When determined by infrared spectroscopy, for example, the encapsulant sheet is measured with an infrared spectrophotometer to obtain an infrared absorption spectrum, and cross-linking is performed on the absorbance peak derived from the methylene group of the polyethylene resin as the base resin. It can be obtained by calculating the ratio of the absorbance peaks (IR peak ratio) of each functional group in the agent, the cross-linking aid and the silane coupling agent. The relationship between the contents of the cross-linking agent, the cross-linking aid and the silane coupling agent and the absorbance can be obtained in advance by the calibration curve method.

3. 3. Manufacturing Method of Encapsulant Sheet An example of the manufacturing method of the encapsulant sheet will be described below. First, it is obtained by a step of mixing each of the above components to obtain a sealing material composition, melting the sealing material composition, forming a film into a sheet, and obtaining an uncrosslinked sealing material sheet.

Examples of the method of mixing each component include a method of impregnating each component with a polyethylene resin as a base resin by dry blending. Further, when a sealing material sheet is obtained by extrusion molding, a cross-linking agent or a cross-linking aid may be added to the polyethylene-based resin as the base resin in a liquid state. Alternatively, a cross-linking aid may be kneaded in advance with a polyethylene-based resin as a base resin and master-batched as a mixture. When a masterbatch is used, the dispersibility of the cross-linking aid is improved, so that the variation in the content of the cross-linking aid in the encapsulant sheet can be suppressed.

The encapsulant sheet of the present disclosure is a film formed by forming the encapsulant composition without substantially cross-linking, and the content range of each component in the encapsulant sheet is the encapsulant composition. It is the same as the content range of each component in the product. The melt molding can be performed by various conventionally known film forming methods such as film forming with a T-die. The film formation temperature can be 80 ° C. to 100 ° C. The encapsulant composition will be described in detail in "C. Encapsulant composition for solar cell module" described later.

The cross-linking treatment is completed by, for example, a high-temperature heat treatment at the time of manufacturing the solar cell module.

4. Others The encapsulant sheet of the present disclosure is an encapsulant sheet at the stage of uncrosslinking after film formation, and the crosslinking may proceed during any process until after integration as a solar cell module. It is a so-called thermosetting resin film that is supposed to be used.

The encapsulant sheet of the present disclosure is an uncrosslinked encapsulant sheet in this way, and its gel fraction is usually 5% or less. On the other hand, the gel fraction of the encapsulant sheet after the completion of crosslinking after integration as a solar cell module, that is, the gel fraction of the encapsulant layer may be 50% or more and 90% or less, and 60% or more and 80%. More preferably:

Here, the “gel fraction (%)” in the present specification refers to 1.0 g of a sealing material in a resin mesh, extracted with xylene at 110 ° C. for 24 hours, then taken out together with the resin mesh, dried and weighed. , The mass before and after extraction was compared, the mass% of the residual insoluble matter was measured, and this was used as the gel fraction.

The gel fraction of 0% means that the residual insoluble matter is substantially 0 and the cross-linking reaction of the encapsulant composition or the encapsulant sheet has not substantially started. More specifically, "gel fraction 0%" means that the residual insoluble matter is not present at all, and the mass% of the residual insoluble matter measured by a precision balance is less than 0.05% by mass. Suppose to say.

In addition, the residual insoluble matter does not include pigment components other than the resin component. When a mixture other than these resin components is mixed in the residual insoluble matter by the above test, for example, by separately measuring the content of these mixture in the resin component in advance, these It is possible to calculate the gel fraction that should be originally obtained for the residual insoluble matter derived from the resin component excluding the mixture.

The film thickness of the sealing material sheet of the present disclosure is not particularly limited, but is preferably 200 μm or more and 1000 μm or less. When the film thickness is at least the above lower limit value, the strength of the encapsulant sheet can be made better. When the film thickness is not more than the above upper limit value, damage to other members such as a transparent substrate can be suppressed in the laminating step. Further, a sufficient light transmittance can be secured, and the solar cell module including this can have a high amount of photovoltaic power generation.

The encapsulant sheet of the present disclosure is preferably used alone as an encapsulant sheet, but may be included as a part of a multi-layer encapsulant sheet having a multi-layer structure. As the multi-layer structure, 2 types 2 layers, 2 types 3 layers and the like are preferably used, and among them, a 2 types 3 layer structure in which a skin layer, a core layer and a skin layer are laminated in this order is preferable. FIG. 2 shows an outline of a multilayer sealing material sheet 20 having a two-kind three-layer structure in which a skin layer 6, a core layer 7, and a skin layer 6 are laminated in this order using the sealing material sheet 100 of the present disclosure. A cross-sectional view is shown. In such a multilayer encapsulant sheet, skin layers are arranged on both outermost surfaces with a predetermined layer thickness according to the encapsulant compositions for the core layer and the skin layer, and the side that comes into close contact with the solar cell element. A skin layer is placed in. The encapsulant sheet of the present disclosure is preferably included as a skin layer of the multilayer encapsulant sheet.

The layer thickness ratio between the skin layer and the core layer is preferably 1: 1.2 to 1:10, more preferably 1: 2 to 1: 7, and particularly preferably 1: 3 to 1: 5. These can be formed by a conventionally known multi-layer coextrusion method or the like.

The core layer is not limited as long as it has a function of imparting desired performance such as heat resistance and appropriate rigidity to the multilayer encapsulant sheet, and for example, a polyethylene resin is used as a base resin and any component is used. Can be contained.

The base resin of the encapsulant composition for the core layer is a low density polyethylene resin (LDPE), a linear low density polyethylene resin (LLDPE), or a metallocene linear low density polyethylene resin (M-LLDPE). Can be preferably used. Above all, from the viewpoint of long-term reliability of the solar cell module, low-density polyethylene-based resin (LDPE) can be particularly preferably used as the composition for the core layer.

B. Multi-layer encapsulant sheet for solar cell module In the present disclosure, the multi-layer encapsulant sheet for a solar cell module having a core layer and skin layers arranged on both sides of the core layer, and the core layer is The skin layer is thicker than the skin layer, and the skin layer uses a polyethylene resin as a base resin, an organic peroxide as a cross-linking agent, and a nurate ring having two or more polymerizable reactive groups in one molecule as a cross-linking aid. The content of the cross-linking agent in the skin layer is 0.33% by mass or more and 0.53% by mass or less, and the content of the cross-linking aid is 0.30. Provided is a multilayer encapsulant sheet for a solar cell module, which has a mass% or more and 0.90 mass% or less and a content of the silane coupling agent of 0.15 mass% or more and 0.40 mass% or less.

As shown in FIG. 2, the multi-layer encapsulant sheet 20 for a solar cell module of the present disclosure has a two-kind three-layer structure in which a skin layer 6, a core layer 7, and a skin layer 6 are laminated in this order.

The polyethylene resin, cross-linking agent, cross-linking aid, silane coupling agent, and other additives in the skin layer, and their contents are described in detail in the above section "A. Encapsulant sheet for solar cell module". Since the contents can be the same as those described above, the description here will be omitted.

Further, in the multilayer encapsulant sheet of the present disclosure, the core layer is thicker than the skin layer. The layer thickness ratio can be the same as that described in detail in the section "A. Encapsulant sheet for solar cell module 4. Others", and thus the description thereof is omitted here. Since the core layer can be the same as the content described in detail in the section "A. Encapsulant sheet for solar cell module 4. Others", the description thereof is omitted here.

C. Encapsulant composition for solar cell module In the present disclosure, the encapsulant composition for a solar cell module is a polyethylene-based resin as a base resin, an organic peroxide as a cross-linking agent, and a cross-linking aid. A nurate ring-containing compound having two or more polymerizable reactive groups in one molecule and a silane coupling agent are contained, and the content of the cross-linking agent in the encapsulant composition is 0.33% by mass or more. 0.53% by mass or less, the content of the cross-linking aid is 0.30% by mass or more and 0.90% by mass or less, and the content of the silane coupling agent is 0.15% by mass or more and 0.40% by mass or less. Provided is a sealing material composition for a solar cell module, which is characterized by being present.

1. 1. Composition of Encapsulant Composition The encapsulant composition of the present disclosure uses a polyethylene resin as a base resin and contains a specific content of the above-mentioned cross-linking agent, the above-mentioned cross-linking aid, and the above-mentioned silane coupling agent as essential components. .. In addition, other additives may be included.

The polyethylene-based resin, cross-linking agent, cross-linking aid, silane coupling agent, and other additives, and their contents are described in detail in the section "A. Encapsulant sheet for solar cell module" above. Since the same can be applied, the description here is omitted.

2. Uses of Encapsulant Composition The encapsulant composition of the present disclosure is a composition used for producing an encapsulant sheet constituting a encapsulant member of a solar cell module, and is molded into a sheet by a conventionally known method. As a result, a single-layer encapsulant sheet can be obtained. Further, the encapsulant composition of the present disclosure can be used for forming a layer of a multi-layer encapsulant sheet having a multi-layer structure such as 2 types 2 layers or 2 types 3 layers. Above all, it is preferable as a composition for forming a skin layer of a multilayer sealing material sheet 20 having a two-kind three-layer structure in which a skin layer 6, a core layer 7, and a skin layer 6 are laminated in this order as shown in FIG. used. In this case, the encapsulant composition for the core layer and the encapsulant composition of the present disclosure for the skin layer are extruded into a sheet by a conventionally known multi-layer coextrusion method or the like to obtain a multi-layer encapsulant sheet.

The composition of the core layer and the layer thickness ratio between the skin layer and the core layer can be the same as those described in detail in the above section "A. Encapsulant sheet for solar cell module". The description is omitted.

D. Solar cell module In the present disclosure, the solar cell element, the front surface side protective member, the back surface side protective member, the above-mentioned sealing material sheet for the solar cell module, the above-mentioned multi-layer sealing material sheet for the solar cell module, and the above-mentioned The solar cell element is arranged between the front surface side protective member and the back surface side protective member, including a sealing material layer which is a crosslinked body of any of the sealing material compositions for a solar cell module. Provided is a solar cell module sealed with the sealing material layer.

1. 1. Configuration of Solar Cell Modules Examples of solar cell modules include solar cell modules in which solar cell elements are sandwiched between sealing material layers and laminated, and both front and back surfaces are covered with protective members. That is, a typical solar cell module has a configuration in which a front surface side protective member, a front surface side encapsulant layer, a solar cell element, a back surface side encapsulant layer, and a back surface side protective member are laminated in this order. FIG. 1 shows a schematic cross-sectional view illustrating the solar cell module of the present disclosure. The solar cell module 10 includes a plurality of solar cell elements 1, a pair of front surface side solar cell encapsulant layer 2 and back surface side solar cell encapsulant layer 3 that sandwich and seal the solar cell element 1, and front surface protection. A member 4 and a back surface side protective member 5 are provided.

(1) Encapsulant layer The encapsulant layer is a crosslinked product obtained by heat-treating the above-mentioned encapsulant sheet, multi-layer encapsulant sheet or the above-mentioned encapsulant composition (sealing shown by 100C in FIG. 1). Material layer), which is a layer for sealing the solar cell element. Since the encapsulant sheet can be the same as the content described in detail in the above section "A. Encapsulant sheet for solar cell module", the description thereof is omitted here. Since the multi-layer encapsulant sheet can be the same as the content described in detail in the above section "B. Multi-layer encapsulant sheet for solar cell module", the description thereof is omitted here. The crosslinked body of the multilayer encapsulant sheet has a crosslinked skin layer, a core layer, and a crosslinked skin layer. Since the encapsulant composition can be the same as the content described in detail in the above section "C. Encapsulant composition for solar cell module", the description thereof is omitted here.

The encapsulant layer typically comprises a front side encapsulant layer and a back surface encapsulant layer, as shown in FIG. 1, the encapsulant sheet, multilayer encapsulant sheet or encapsulation of the present disclosure. The material composition is used to form one or both of the front surface side encapsulant layer and the back surface side encapsulant layer, and these encapsulant layers are the encapsulant sheet, the multilayer of the present disclosure. It can be formed by cross-linking a sealing material sheet or a sealing material composition.

The encapsulant layer in the present disclosure typically seals the solar cell element by sandwiching it between a pair of encapsulant sheets arranged on both sides thereof, as shown in FIG. It is a layer, but it is not limited to this. For example, in a thin-film solar cell module having a structure in which a cell glass having a thin-film solar cell element formed on a glass substrate is coated with a sealing material layer, the cell glass is formed on the cell glass. The encapsulant layer covering the thin film element can be regarded as the encapsulant layer of the solar cell module.

(2) Solar cell elements Solar cell elements include silicon-based devices such as single crystal silicon, polycrystalline silicon, and amorphous silicon, group III-V such as gallium-arsenide, copper-indium-selenium, and cadmium-tellu, and II-VI. Various solar cell elements such as group compound semiconductors can be used. In the solar cell module, a plurality of solar cell elements are electrically connected in series via an interconnector having a conducting wire and a solder joint.

(3) Surface-side protective member Examples of the surface-side protective member include a glass plate; a transparent substrate such as a resin plate formed of an acrylic resin, polycarbonate, polyester, a fluorine-containing resin, or the like. The solar cell encapsulant sheet of the present disclosure exhibits good adhesiveness to the transparent surface side protective member.

(4) Back surface side protective member Examples of the back surface side protective member (back sheet) include a single sheet such as a metal or various thermoplastic resin films, or a multi-layer sheet. Examples thereof include metals such as tin, aluminum and stainless steel; inorganic materials such as glass; various thermoplastic resin films formed of polyester, inorganic vapor-deposited polyester, fluorine-containing resin, polyolefin and the like. The back surface side protective member may be a single layer or a plurality of layers. The solar cell encapsulant sheet of the present disclosure exhibits good adhesiveness to the back surface side protective member.

2. Manufacturing Method of Solar Battery Module In the solar cell module of the present disclosure, for example, a sealing material sheet is manufactured using the above-mentioned sealing material composition (sealing material sheet manufacturing process), and then the above-mentioned surface side protective member is manufactured. , Encapsulant sheet, solar cell element, encapsulant sheet, and backside protective member are sequentially laminated and then integrated by vacuum suction or the like, and then the above member is formed by a molding method such as a lamination method. It can be manufactured by heat-pressing molding as an integrally molded body (module integration process).

(1) Encapsulant sheet manufacturing process The encapsulant sheet is manufactured in the same manner as described in detail in the above section "A. Encapsulant sheet for solar cell module 3. Manufacturing method of encapsulant sheet". Therefore, the description here is omitted.

(2) Module integration process As described above, each member including the uncrosslinked encapsulant sheet obtained in the encapsulant sheet manufacturing process is heat-press-molded as an integrally molded body by a molding method such as vacuum heating lamination. do. In this integration step, the cross-linking is advanced so that the gel fraction of the uncross-linked encapsulant sheet is within the above-mentioned range. If necessary according to the lamination conditions, a separate thermal cross-linking treatment may be further performed after modularization.

D. Method for manufacturing encapsulant sheet for solar cell module In the present disclosure, it is a method for producing an encapsulant sheet for a solar cell module, which is polymerizable of two or more in one molecule which is a polyethylene resin and a cross-linking aid. A step of mixing a nurate ring-containing compound having a reactive group to obtain a mixture, and a step of mixing the above mixture, an organic peroxide as a cross-linking agent, and a silane coupling agent to obtain a sealing material composition. And the step of melting the encapsulant composition and forming a film into a sheet to obtain an uncrosslinked encapsulant sheet, and the content of the crosslinking agent in the encapsulant sheet is , 0.33% by mass or more and 0.53% by mass or less, the content of the cross-linking aid is 0.30% by mass or more and 0.90% by mass or less, and the content of the silane coupling agent is 0.15% by mass or more. Provided is a method for producing a sealing material sheet for a solar cell module, which is 0.40% by mass or less.

The method for manufacturing the encapsulant sheet can be the same as that described in detail in the above section "A. Encapsulant sheet for solar cell module 3. Manufacturing method for encapsulant sheet". The description of is omitted.

Note that the present disclosure is not limited to the above embodiment. The above embodiment is an example, and any object having substantially the same structure as the technical idea described in the claims of the present disclosure and exhibiting the same effect and effect is the present invention. Included in the technical scope of the disclosure.

The present disclosure will be described in more detail with reference to Examples and Comparative Examples below.

(Examples 1 to 6, Comparative Examples 1 to 6)
[Formation of encapsulant sheet]
The following polyethylene resin as a base resin, the following TBEC as a cross-linking agent, the following TAIC as a cross-linking aid, the following silane coupling agent, and the following additives were mixed to obtain a sealing material composition. The encapsulant composition was melted and formed into a film having a thickness of 450 μm by the T-die method to obtain an uncrosslinked single-layer encapsulant sheet for a solar cell module. The film formation temperature was 90 ° C to 100 ° C.

-Polyethylene resin: Product name KS650 (manufactured by Japan Polyethylene Corporation, density 0.886 g / cm ³ , MFR20)
-Crosslinking agent: Product name TBEC (boiling point 310 ° C, density 0.927 g / ml, 1-hour half-life temperature 121 ° C, manufactured by Alchema Yoshitomi Co., Ltd.)
-Crosslinking aid: Product name TAIC (boiling point 151 ° C, density 1.159 g / ml, manufactured by Mitsubishi Chemical Corporation)
-Silane coupling agent: Product name KBM-503 (3-methacryloxypropyltrimethoxysilane, manufactured by Shinetsu Silicone Co., Ltd.)
-Ultraviolet absorber 1: Product name kemisorb12 (benzophenone-based ultraviolet absorber, molecular weight 326, melting point 47 °, specific gravity (25 ° C) 1.16, manufactured by Chemipro Kasei Co., Ltd.)
-Ultraviolet absorber 2: Product name kemisorb79 (melting point ≥ 103-105 ° C, specific gravity (20 ° C) 1.18 / cm ³ , manufactured by Chemipro Kasei Co., Ltd.)
-Weather resistant HALS: XT850 (NOR type hindered amine type, manufactured by BASF Japan Ltd.)

[Specification of encapsulant sheet composition by infrared spectroscopy]
(Measurement pretreatment)
The content (mass%) of each component in the encapsulant sheet was calculated from the absorbance ratio of the infrared absorption spectrum by infrared spectroscopy. First, since the surface of the encapsulant sheet may have a shape such as embossing, the surface of the encapsulant sheet was flattened. In the flattening treatment, the encapsulant sheet is sandwiched between release films, and the temperature is 85 ° C., evacuation for 1.5 minutes, and pressure is held in the state of base glass / release film / encapsulant sheet / release film. Vacuum laminating was performed in 5 minutes (40 kPa) to smooth the sheet surface.

(Measurement by infrared spectroscopy)
Next, after performing background measurement using a Fourier transform infrared spectrophotometer (FT / IR-610, manufactured by JASCO Corporation) in the absence of a sample, Examples 1 to 5 and Comparative Examples 1 to 6 A sample of the encapsulant sheet was set, and measurement was performed by infrared spectroscopy under the measurement conditions of measurement mode: transmission measurement, detector: TGC, resolution: 4 cm ^{-1, and number of integrations: 64.}

By the above measurement, an infrared absorption spectrum having the following peak was obtained.
Methylene group of polyethylene resin: 2021 cm ^-1 (baseline 2091-1987 cm ^-1 )
Carbonyl group of cross-linking agent TBEC: 1793 cm ^-1 (baseline 1815-1777 cm ^-1 )
Vinyl group of cross-linking aid TAIC: 990 cm ^-1 (baseline 1007-872 ^{cm -1} )
Carbonyl group of silane coupling agent: 1722 cm ^-1 (baseline 1815-1658 cm ^-1 )

The height from the baseline of the peak top near the ^{wave number 2021 cm -1} was determined as the absorbance derived from the methylene group of the polyethylene resin. Similarly, the height from the baseline of the peak top near the ^{wave number of 1793 cm -1} was determined as the absorbance derived from the carbonyl group of the cross-linking agent. The height from the baseline of the peak top near the ^{wave number of 990 cm -1} was determined as the absorbance derived from the vinyl group of the cross-linking aid. The height from the baseline of the peak top near the ^{wave number of 1722 cm -1} was determined as the absorbance derived from the carbonyl group of the silane coupling agent.

The value (peak ratio) obtained by dividing the height of the peak top of each of the cross-linking agent, the cross-linking aid, and the silane coupling agent by the height of the peak top of polyethylene was calculated.
Peak ratio (crosslinking agent) = peak height (crosslinking agent) / peak height (polyethylene)
Peak ratio (crosslinking aid) = peak height (crosslinking aid) / peak height (polyethylene)
Peak ratio (silane coupling agent) = peak height (silane coupling agent) / peak height (polyethylene)

(Calibration curve creation)
Three or more standard samples with known addition amounts of each additive and different addition amounts were prepared, IR measurements were performed on the standard samples, and peak analysis was performed. The component concentration of the standard sample was plotted on the horizontal axis and the peak ratio was plotted on the vertical axis to create an approximate line. As an example of the approximate expression of the cross-linking agent, y (peak ratio of the cross-linking agent) = 8.8263x (content of the cross-linking agent (% by mass)) + 0.4787 was obtained.

Based on the calibration curve prepared above and the peak ratio value of the encapsulant sheet, the contents of the cross-linking agent, the cross-linking aid, and the silane coupling agent are calculated, and the contents of other additives in the composition are also calculated. Based on this, the content of each component in the encapsulant sheet was calculated. The results are shown in Table 1.

(Evaluation method)
The encapsulant sheets of each Example and Comparative Example were evaluated for the gel fraction, glass adhesion, outgas amount, presence / absence of bubbles (bubble test), and presence / absence of bleeding after the cross-linking treatment. The results are shown in Table 1.

[Gel fraction calculation]
In order to evaluate the degree of cross-linking of the encapsulant layer in the state of being integrated as a solar cell module, each of the encapsulant sheets is sandwiched between release films, and the temperature is 155 ° C., evacuation is 6 minutes, and pressure is maintained. The laminating treatment was performed in 11 minutes (70 kPa). About 1 g of this sealing material was weighed (W1), wrapped with a resin mesh, and weighed (W2). Next, the encapsulant was placed in xylene at 110 ° C., stirred for 24 hours, and dried in an oven at 110 ° C. for 4 hours. After the drying treatment, the mass was weighed (W3), and the gel fraction was calculated by the following formula.
Gel fraction = (1- (W2-W3) / W1) x 100

[Glass adhesion evaluation]
A sealing material sheet cut in the MD direction of 100 mm x TD direction of 75 mm is placed on a 50 mm x 75 mm white plate tempered glass, and laminated at a temperature of 155 ° C., vacuuming for 6 minutes, and pressure holding for 11 minutes (70 kPa) to achieve glass adhesion. An evaluation sample was prepared. This sample was cut with a width of 15 mm in the flow direction, and the cut portion was measured with a TENSILON universal testing machine RTE-1210 (manufactured by ORIENTEC) at a peeling angle of 180 ° and a peeling speed of 50 mm / min.

[Measurement of outgassing amount]
The amount of outgas generated during the manufacture of the solar cell module was measured using headspace gas chromatography (HS-GC / MS). 200 mg of the encapsulant sheet was treated at 165 ° C. for 30 minutes, and the generated gas was introduced into the above GC / MS. The column temperature was raised from 40 ° C. to 320 ° C. and detected by a hydrogen flame detector (FID). The peak area of the entire area was defined as the outgas amount (unit: pA · sec).

[Excipient bleed evaluation]
The encapsulant sheet was stored at room temperature, and after 1 week, it was evaluated as "x" if there was obvious stickiness (the level at which the waste was wet when the surface was wiped with a waste cloth), and "○" if there was no stickiness. ..

[Bubble evaluation (bubble test)]
A sealing material sheet was sandwiched between 5 cm square glass, and butyl rubber was placed at the end. A sample laminated at a temperature of 155 ° C., evacuation for 6 minutes, and pressure holding for 11 minutes (70 kPa) was put into an oven at 190 ° C., and the state after 1 hour was observed. , The case where no bubbles were generated was set as "○".

From the results in Table 1, it was found that as the amount of the cross-linking agent increased, more outgas was generated, and when the amount of the cross-linking agent added was excessive, bubbles were generated (Comparative Example 1). On the other hand, it was found that the gel fraction decreased when the amount of the cross-linking agent added was small (Comparative Example 2).

The amount of the cross-linking aid has almost no effect on the amount of outgas, but bleeding occurs when the amount of the cross-linking aid added is large (Comparative Example 3), and the gel fraction decreases when the amount of the cross-linking aid added is small. It was found (Comparative Example 4). Further, it was found that the amount of the silane coupling agent added had almost no effect on the amount of outgas, but the gel fraction decreased when the amount added was large (Comparative Example 5), and the glass adhesion decreased when the amount added was small. (Comparative Example 6).

On the other hand, the encapsulant sheets of Examples 1 to 6 in which the contents of the cross-linking agent, the cross-linking aid, and the silane coupling agent are within the range of the present disclosure can be used for bleeding of additives and when manufacturing a solar cell module. It was possible to manufacture a highly reliable solar cell module that satisfies the required characteristics such as adhesion to glass and high gel fraction while suppressing the generation of outgas.

1 ... Solar cell element 2 ... Front side solar cell encapsulant layer 3 ... Back side solar cell encapsulant layer 4 ... Front side protective member 5 ... Back side protective member 6 ... Back side protective member 6 ... Skin layer 7 ... Core layer 10 ... Solar cell module 20 ... Multi-layer encapsulant sheet 100 ... Encapsulant sheet

Claims (6)

1. A sealing material sheet for solar cell modules
   Using polyethylene resin as the base resin
   It contains an organic peroxide as a cross-linking agent, a nulate ring-containing compound having two or more polymerizable reactive groups in one molecule as a cross-linking aid, and a silane coupling agent.
   The content of the cross-linking agent in the encapsulant sheet is 0.33% by mass or more and 0.53% by mass or less.
   The content of the cross-linking aid is 0.30% by mass or more and 0.90% by mass or less,
   A sealing material sheet for a solar cell module having a content of the silane coupling agent of 0.15% by mass or more and 0.40% by mass or less.
2. The encapsulant sheet for a solar cell module according to claim 1, wherein the encapsulant sheet for the solar cell module has a thickness of 300 μm or more and 900 μm or less and has a single-layer structure.
3. A multi-layer encapsulant sheet for a solar cell module having a core layer and skin layers arranged on both sides of the core layer.
   The core layer is thicker than the skin layer
   The skin layer is made of a polyethylene resin as a base resin.
   It contains an organic peroxide as a cross-linking agent, a nulate ring-containing compound having two or more polymerizable reactive groups in one molecule as a cross-linking aid, and a silane coupling agent.
   The content of the cross-linking agent in the skin layer is 0.33% by mass or more and 0.53% by mass or less.
   The content of the cross-linking aid is 0.30% by mass or more and 0.90% by mass or less,
   A multilayer encapsulant sheet for a solar cell module having a content of the silane coupling agent of 0.15% by mass or more and 0.40% by mass or less.
4. Encapsulant composition for solar cell modules
   Using polyethylene resin as the base resin
   It contains an organic peroxide as a cross-linking agent, a nulate ring-containing compound having two or more polymerizable reactive groups in one molecule as a cross-linking aid, and a silane coupling agent.
   The content of the cross-linking agent in the encapsulant composition is 0.33% by mass or more and 0.53% by mass or less.
   The content of the cross-linking aid is 0.30% by mass or more and 0.90% by mass or less,
   A sealing material composition for a solar cell module, wherein the content of the silane coupling agent is 0.15% by mass or more and 0.40% by mass or less.
5. The solar cell element, the front surface side protective member, the back surface side protective member, the encapsulant sheet for the solar cell module according to claim 1 or 2, and the multilayer encapsulant for the solar cell module according to claim 3. A sheet and a sealing material layer which is a crosslinked product of any of the sealing material compositions for a solar cell module according to claim 4 are included.
   A solar cell module in which the solar cell element is sealed by the sealing material layer arranged between the front surface side protective member and the back surface side protective member.
6. A method for manufacturing a sealing material sheet for a solar cell module.
   A step of mixing a polyethylene-based resin and a nurate ring-containing compound having two or more polymerizable reactive groups in one molecule of a cross-linking aid to obtain a mixture, and a step of obtaining a mixture.
   A step of mixing the mixture, an organic peroxide as a cross-linking agent, and a silane coupling agent to obtain a sealing material composition.
   It comprises a step of melting the encapsulant composition and forming a film into a sheet to obtain an uncrosslinked encapsulant sheet.
   The content of the cross-linking agent in the encapsulant sheet is 0.33% by mass or more and 0.53% by mass or less.
   The content of the cross-linking aid is 0.30% by mass or more and 0.90% by mass or less,
   A method for producing a sealing material sheet for a solar cell module, wherein the content of the silane coupling agent is 0.15% by mass or more and 0.40% by mass or less.

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