JP2016143772A - Sealing composition, sealing material, solar cell including sealing composition, and light-emitting material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sealing composition, excellent in adhesion, transparency, and insulation, particularly useful for a solar cell.SOLUTION: The sealing composition includes silica and a silane-modified product of an ethylene-vinyl acetate copolymer. The sealing composition includes 0.1 to 5 pts.mass of silica with respect to 100 pts.mass of the composition.SELECTED DRAWING: None

Description

  The present invention relates to a composition for a sealing material. More specifically, the present invention relates to a composition for a sealing material excellent in adhesiveness, transparency, insulation, the sealing material formed by molding the composition for sealing material, and the composition for sealing material The present invention relates to a solar cell and a light-emitting element using the object.

  In recent years, in response to an improvement in awareness of energy saving and environmental problems, expectations for solar cells that produce clean energy are increasing, and such batteries are becoming popular. As solar cells, for example, crystalline silicon solar cells and thin film solar cells (in the present invention, these are collectively referred to as solar cells) are known. In addition, a large-scale photovoltaic power generation facility called a mega solar having these solar cells connected in series and having an output of 1 MW or more is increasing.

  Recently, in such a mega solar photovoltaic power generation facility, the performance degradation of the solar cell module called PID (Potential Induced Migration) phenomenon that has not occurred in the conventional solar cell module has occurred and has become a problem. The PID phenomenon is a phenomenon in which output polarization is significantly reduced by polarization of electric charge in the internal circuit of the solar cell module and hindering movement of electrons inside the cell. This is because, in a photovoltaic power generation facility where the system voltage is increased, a large potential difference occurs between the grounded frame and the internal circuit of the solar cell module, and external factors such as humidity and temperature are caused by this. It is said that this is caused by a leakage current generated between the internal circuit of the module and the frame.

  These solar cells are generally solar cells as a solar cell module in which a surface protective layer, a photoelectric conversion layer including a power generation element such as a solar cell, and a back surface protective layer are laminated in this order from the side receiving sunlight. Used for photovoltaic power generation. Specifically, a photoelectric conversion layer in which a plurality of solar cells are connected by a wire or the like is sandwiched between protective layers such as a front surface protective layer and a back surface protective layer in a sealing material sheet, and the entire module is vacuumed. It is common to produce by vacuum drawing by heating and pressing with a laminator.

  Conventionally, as a sealing material sheet used for such a solar cell module, an ethylene vinyl acetate copolymer (hereinafter also referred to as EVA), an ethylene ethyl acrylate copolymer (EEA), or the like and a polar monomer. A film made of a copolymer is used, and in particular, an EVA film is preferably used because it is inexpensive and has high transparency. And for the film made of a copolymer of ethylene and a polar monomer for the encapsulant sheet, in order to improve the film strength, durability, weather resistance, adhesiveness, etc. of the encapsulant sheet, Resin compositions obtained by grafting EVA with a silane coupling agent or the like that improves density are known (for example, Patent Documents 1 and 2). Further, as a sealing film that can suppress the occurrence of the PID phenomenon, it is composed of a cured film of a composition containing an ethylene-polar monomer copolymer and a crosslinking agent, and has a volume resistivity and a thickness of the solar battery sealing film A sealing film having a specific value is proposed, and it is proposed that the composition further contains a silane coupling agent (Patent Document 3).

JP 58-63178 A JP2002-9309 JP2014-027034

  As described above, it is extremely important to suppress the occurrence of the PID phenomenon in a photovoltaic power generation facility with a high system voltage in order to obtain a stable power generation output. Since the PID phenomenon occurs due to a leakage current between the internal circuit of the module and the frame, it is important to use a solar cell sealing film having high insulation properties in order to suppress the occurrence of the PID phenomenon.

  On the other hand, according to the detailed examination of the present inventors, the silane-modified body of the ethylene-vinyl acetate copolymer as described in Patent Documents 1 and 2 has insulation properties necessary for use as a sealing material. It turned out to be insufficient. Further, it was found that the composition of the ethylene-vinyl acetate copolymer and the silane coupling agent as described in Patent Document 3 has insufficient adhesiveness such as the time for developing the adhesive force.

  The object of the present invention is to solve various problems of these techniques. Therefore, the subject of this invention is providing the composition for sealing materials excellent in adhesiveness, transparency, insulation, etc. Moreover, the subject of this invention is providing the solar cell and light emitting element which use the film formed by shape | molding this composition for sealing materials, and this composition for sealing materials.

  As a result of intensive studies in view of various problems of the conventional technology, the present inventor has found that a composition for a sealing material in which a specific amount of a silane-modified ethylene-vinyl acetate copolymer and silica are blended is used. It was found to solve the problem. That is, the gist of the present invention is as follows [1] to [8].

[1] An encapsulant composition comprising 0.1 to 5 parts by mass of silica with respect to 100 parts by mass in total, comprising a silane-modified ethylene-vinyl acetate copolymer and silica. .
[2] The composition for sealing material according to [1], wherein the silica is granular silica having an average primary particle size of 0.1 to 1000 nm.
[3] The composition for sealing material according to [1] or [2], wherein a melt flow rate (MFR) at 190 ° C. and a load of 2.16 kg is 0.1 to 30 g / 10 minutes.
[4] The silane-modified product of the ethylene-vinyl acetate copolymer is obtained by reacting a vinylsilane compound with an ethylene-vinyl acetate copolymer, according to any one of [1] to [3]. The composition for sealing materials.
[5] A sealing material formed by molding the composition for sealing material according to any one of [1] to [4].
[6] A solar cell comprising the encapsulant composition according to any one of [1] to [4].
[7] A light emitting device comprising the encapsulant composition according to any one of [1] to [4].

  According to this invention, the composition for sealing materials excellent in adhesiveness, transparency, insulation, etc. is provided. Moreover, according to this invention, the solar cell and light emitting element which use the film formed by shape | molding this composition for sealing materials, and this composition for sealing materials are provided.

  Embodiments of the present invention will be described in detail below, but the present invention is not limited to the following descriptions, and can be arbitrarily modified and implemented without departing from the gist of the present invention. In addition, in this specification, when expressing by putting a numerical value or a physical-property value before and behind using "-", it shall use as what includes the value before and behind.

[Composition for encapsulant]
The composition for sealing material of this invention contains the silane modified body of ethylene-vinyl acetate copolymer, and a silica, and contains 0.1-5 mass parts of silica with respect to these 100 mass parts in total. The composition for a sealing material of the present invention is excellent in adhesiveness, transparency, insulation and the like.

  In particular, excellent adhesiveness is considered to be due to silane modification of the ethylene-vinyl acetate copolymer. This is considered to be due to the chemical reaction of the silane functional group grafted on the ethylene-vinyl acetate copolymer with the surface of the adherend.

  Usually, an ethylene-vinyl acetate copolymer is excellent in insulation, but when it is modified with silane, the insulation tends to be lowered. In the present invention, it has been found that by using a combination of a silane-modified body of an ethylene-vinyl acetate copolymer and silica, the insulation can be further improved as compared with an unmodified ethylene-vinyl acetate copolymer. This is a combination of silica and ethylene-vinyl acetate copolymer modified silane, which improves the compatibility of silica and ethylene-vinyl acetate copolymer, provides excellent insulation, and silica and unsaturated. This is considered to be due to the reaction of the silane compound and the reduction of the unreacted unsaturated silane compound contained in the modified product.

[Silane modified product of ethylene-vinyl acetate copolymer]
The silane-modified ethylene-vinyl acetate copolymer used in the present invention is obtained by graft-modifying an unsaturated silane compound on an ethylene-vinyl acetate copolymer.

<Ethylene-vinyl acetate copolymer>
In the present invention, the ethylene-vinyl acetate copolymer is not particularly limited as long as it is a copolymer of ethylene and vinyl acetate, but usually the vinyl acetate in the ethylene-vinyl acetate copolymer. The content of the derived partial structure is preferably from 5 to 90 mass%, more preferably from 10 to 50 mass%, particularly preferably from 25 to 35 mass%, based on the ethylene-vinyl acetate copolymer. If the content of vinyl acetate in the ethylene-vinyl acetate copolymer is too low, the resulting sealing material tends to be hard and the transparency of the sealing material may be reduced. Moreover, when too high, the hardness of a sealing material may be inadequate and workability may fall.

  In the present invention, the melt flow rate (MFR) of the ethylene-vinyl acetate copolymer is a melt flow rate (MFR) measured at 190 ° C. under a load of 2.16 kg in accordance with JIS K7210 (1999). Usually, it is 0.1-50 g / 10min. If the MFR is too large, when the element is laminated as a sealing material, the protrusion of the molten resin tends to increase, and it may be difficult to stably seal the element. Moreover, when MFR is too small, there exists a tendency for a bubble to become difficult to escape and it may become easy to generate | occur | produce sealing failure. From these viewpoints, the MFR of the ethylene-vinyl acetate copolymer is preferably 1 g / 10 min or more, more preferably 5 g / 10 min or more, while preferably 40 g / 10 min or less, more Preferably it is 35 g / 10 minutes or less.

  In the present invention, the ethylene-vinyl acetate copolymer can be obtained as a commercial product. For example, an applicable product can be selected and used from EVAFLEX (registered trademark) series manufactured by Mitsui DuPont, Ultrasen manufactured by Tosoh Corporation, or the like.

<Unsaturated silane compound>
In the present invention, the unsaturated silane compound used for the production of the silane-modified ethylene-vinyl acetate copolymer is not limited, but an unsaturated silane compound represented by the following formula (1) is preferably used.
RSi (R ′) ₃ (1)

[Wherein, R represents an ethylenically unsaturated hydrocarbon group, R ′ represents a hydrocarbon group having 1 to 10 carbon atoms or an alkoxy group having 1 to 10 carbon atoms, and a plurality of R ′ may be the same or different from each other. And at least one of R ′ is an alkoxy group having 1 to 10 carbon atoms. ]

  In the formula (1), R is preferably an ethylenically unsaturated hydrocarbon group having 2 to 10 carbon atoms, more preferably 2 to 6 carbon atoms, still more preferably an ethylenically unsaturated hydrocarbon having 2 to 4 carbon atoms. It is a group. Specific examples include alkenyl groups such as vinyl group, propenyl group, butenyl group, and cyclohexenyl group.

  In the formula (1), R ′ is preferably a hydrocarbon group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms, more preferably a hydrocarbon group having 1 to 4 carbon atoms or 1 to 4 carbon atoms. Of the alkoxy group. Further, at least one of R ′ is preferably an alkoxy group having 1 to 6 carbon atoms, and more preferably an alkoxy group having 1 to 4 carbon atoms. The hydrocarbon group having 1 to 10 carbon atoms of R ′ may be any of an aliphatic group, an alicyclic group, and an aromatic group, but is preferably an aliphatic group. In addition, the alkoxy group having 1 to 10 carbon atoms of R ′ may be linear, branched or cyclic, but is preferably linear or branched. When R ′ is a hydrocarbon group, specifically, an alkyl group represented by methyl group, ethyl group, isopropyl group, t-butyl group, n-butyl group, i-butyl group, cyclohexyl group, etc., or phenyl An aryl group typified by a group and the like can be mentioned. When R ′ is an alkoxy group, specific examples include a methoxy group, an ethoxy group, an isopropoxy group, a β-methoxyethoxy group, and the like. R ′ is particularly preferably an alkoxy group having 1 to 4 carbon atoms from the viewpoint of a crosslinking reaction described later.

  When the unsaturated silane compound is represented by the formula (1), at least one of the three R ′ is an alkoxy group, it is preferable that two R ′ are alkoxy groups, and all R ′ are More preferably, it is an alkoxy group. The plurality of R's may be the same or different from each other, but are preferably the same from the viewpoint of availability.

  As the unsaturated silane compound, among the compounds represented by the formula (1), vinyltrialkoxysilanes represented by vinyltrimethoxysilane, vinyltriethoxysilane, propenyltrimethoxysilane and the like are desirable. This is because the vinyl group enables modification to the ethylene-vinyl acetate copolymer, and the later-described crosslinking reaction proceeds by the alkoxy group. That is, an alkoxy group introduced by graft-modifying an ethylene-vinyl acetate copolymer with an unsaturated silane compound reacts with water in the presence of a silanol condensation catalyst to hydrolyze to produce a silanol group. By dehydrating and condensing with each other, the ethylene-vinyl acetate copolymers are bonded to each other to cause a crosslinking reaction.

  In addition, these unsaturated silane compounds may be used individually by 1 type, and may use 2 or more types together.

  The amount of modification of the unsaturated silane compound in the modified silane of the ethylene-vinyl acetate copolymer used in the present invention (the amount of unsaturated silane compound introduced into the ethylene-vinyl acetate copolymer by graft modification) is not particularly limited, Usually, it is 0.1-5 mass%. When the amount of modification is within this range, the heat resistance and the adhesiveness when used as a sealing material tend to be good, and the appearance tends to be good. From the viewpoint of making these better, the amount of modification of the unsaturated silane compound is preferably 0.2% by mass or more, more preferably 0.3% by mass or more, while preferably 5.0%. It is not more than mass%, more preferably not more than 3.0 mass%. The amount of modification of the unsaturated silane compound is the mass ratio of the unsaturated silane compound introduced by graft modification to the ethylene-vinyl acetate copolymer before modification, and the sample is burned by heating to ash, and the ash content is alkalinized. It can be melted and dissolved in pure water and then quantified, and confirmed by ICP emission spectrometry using a high-frequency plasma emission spectrometer.

  In addition, the silane modified body of the ethylene-vinyl acetate copolymer used in the present invention may be one obtained by graft-modifying a compound other than the unsaturated silane compound as long as the effects of the present invention are not impaired. Specific examples of compounds other than unsaturated silane compounds include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, ethacrylic acid, maleic acid, fumaric acid, tetrahydrophthalic acid, itaconic acid, citraconic acid, crotonic acid, and isocrotonic acid. Examples include acid, furanic acid, hexadienoic acid, and acid anhydrides thereof.

  The melt flow rate (MFR) of the modified silane of ethylene-vinyl acetate copolymer used in the present invention is a melt flow rate (MFR) at 190 ° C. and a load of 2.16 kg in accordance with JIS K7210 (1999). Usually, 0.1 to 50 g / 10 minutes, preferably 1 to 30 g / 10 minutes. If the MFR is too large, when the element is laminated as a sealing material, the protrusion of the molten resin tends to increase, and it may be difficult to stably seal the element. Moreover, when MFR is too small, there exists a tendency for a bubble to become difficult to escape and it may become easy to generate | occur | produce sealing failure.

[silica]
It is preferable that the composition for sealing materials of this invention contains a silica further. By containing silica, the composition for sealing materials excellent in insulation can be obtained.

The shape of silica is not particularly limited, but is usually granular. Here, the granular form includes, for example, a spherical shape, a granular shape, and an irregular shape (having an irregular shape or an irregular shape). The shape of the filler is preferably at least one selected from the group consisting of spherical, granular, and irregular shapes from the viewpoint that the thermoplastic resin is easily adsorbed. The upper limit of the average primary particle diameter of silica is usually 1000 nm, preferably 500 nm, more preferably 100 nm, and still more preferably 10 nm. The lower limit of the average primary particle diameter of silica is not particularly limited, but is usually 0.1 nm, preferably 0.5 nm, and more preferably 1 nm. It is preferable for the average primary particle size to be not more than the above upper limit because the optical properties of the particles and the composition for a sealing material are likely to be good. Moreover, it is preferable for it to be equal to or more than the lower limit value because an increase in viscosity due to the addition of silica is suppressed and the fluidity of the composition for sealing material is improved.

In addition, in this invention, the average primary particle diameter of a silica can obtain | require the specific surface area measured value (based on JISZ8830) by a BET adsorption method, and can obtain | require it as a conversion value from the following formula | equation.
[Average primary particle diameter (nm)] = 6,000 / [[specific surface area (m ² / g)]
× [Density (g / cm ³ )]]

  The composition for a sealing material of the present invention contains 0.1 to 5 parts by mass of silica with respect to 100 parts by mass in total of the silane-modified ethylene-vinyl acetate copolymer and silica. The content of silica is more preferably 0.2 parts by mass or more, and more preferably 3 parts by mass or less. If the silica content is less than 0.1 parts by mass, the intrinsic deposition resistance of the film in which the composition is used is small and the insulating property is poor, which is not preferable. On the other hand, when the content of silica is more than 5 parts by mass, the transparency of the film obtained using the composition is inferior, and the amount of light received when the film is used for a solar cell or the like is inferior. Therefore, it is not preferable.

[Other ingredients]
The composition for a sealing material of the present invention includes a compounding agent commonly used in resin compositions, inorganic particles other than silica, and resins other than silane-modified products of ethylene-vinyl acetate copolymer (hereinafter referred to as “other resins”). Etc.) etc. can be contained in the range which does not impair the effect of this invention. Examples of such a compounding agent include a heat stabilizer, an ultraviolet absorber, a light stabilizer, an antioxidant, an antistatic agent,
A crystal nucleating agent, a rust inhibitor, a viscosity modifier, a pigment, etc. can be mentioned.

  Among these, it is preferable to contain an antioxidant, particularly a phenol-based, sulfur-based, or phosphorus-based antioxidant. The antioxidant is usually preferably contained in an amount of 0.1 to 1 part by mass with respect to 100 parts by mass of the ethylene-vinyl acetate copolymer.

  Moreover, you may contain a ultraviolet absorber. Specific examples of the ultraviolet absorber include 2-hydroxy-4-normal-octyloxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,2-dihydroxy-4-methoxybenzophenone, and 2-hydroxy-4-methoxy. Benzophenone series such as -4-carboxybenzophenone and 2-hydroxy-4-N-octoxybenzophenone; 2- (2-hydroxy-3,5-di-t-butylphenyl) benzotriazole, 2- (2-hydroxy- Examples include benzotrialisoles such as 5-methylphenyl) benzotriazole; salicylic acid esters such as phenylsulcylate and p-octylphenylsulcylate. The ultraviolet absorber is usually preferably contained in an amount of 0.01 to 1.0 part by mass with respect to 100 parts by mass of the ethylene-vinyl acetate copolymer. These ultraviolet absorbers may be used alone or in combination of two or more.

  Specific examples of inorganic particles other than silica that can be used in the composition for a sealing material of the present invention include alumina, titania, zeolite, mica, synthetic mica, calcium oxide, zirconium oxide, zinc oxide, and fluoride. Examples thereof include magnesium, smectite, synthetic smectite, vermiculite, ITO (indium oxide / tin oxide), ATO (antimony oxide / tin oxide), tin oxide, indium oxide, and antimony oxide. These inorganic particles may be used alone or in combination of two or more.

  Examples of other resins that can be used in the composition for a sealing material of the present invention include polyolefin resins; polyphenylene ether resins; polyamide resins such as nylon 6, nylon 66, and nylon 11; polycarbonate resins; polyethylene terephthalate, Examples thereof include polyester resins such as polybutylene terephthalate; (meth) acrylic resins such as polymethyl methacrylate resins; thermoplastic resins such as styrene resins such as polystyrene; and various thermoplastic elastomers. Other resins may be used alone or in combination of two or more.

[Method for producing composition for sealing material]
The silane modified body of the ethylene-vinyl acetate copolymer used in the present invention can be produced by graft-modifying the unsaturated silane compound to the ethylene-vinyl acetate copolymer. The graft modification method is not particularly limited and can be performed according to a known method. For example, solution modification, melt modification, solid phase modification by irradiation with electron beam or ionizing radiation, modification in a supercritical fluid, and the like are preferable. Used for. Among these, melt modification excellent in equipment and cost competitiveness is preferable, and melt kneading modification using an extruder excellent in continuous productivity is more preferable. Examples of the apparatus used for melt kneading modification include a single screw extruder, a twin screw extruder, a Banbury mixer, and a roll mixer. Among these, a single screw extruder and a twin screw extruder excellent in continuous productivity are preferable.

Generally, graft modification of an unsaturated silane compound onto an ethylene-vinyl acetate copolymer generates a carbon radical by cleaving the carbon-hydrogen bond of the ethylene-vinyl acetate copolymer, and an unsaturated functional group is added thereto. It is carried out by a graft reaction such as As a generation source of the carbon radical, in addition to the above-described electron beam and ionizing radiation, a high temperature method or a radical generator such as an organic or inorganic peroxide can be used. It is preferable to use an organic peroxide from the viewpoint of cost and operability.

  Although there is no limitation in the radical generator used when manufacturing the silane modified body of ethylene-vinyl acetate copolymer, For example, in hydroperoxide, dialkyl peroxide, diacyl peroxide, peroxyester, and a ketone peroxide group. Examples thereof include organic peroxides and azo compounds.

  Specifically, for example, the hydroperoxide group includes cumene hydroperoxide, tertiary butyl hydroperoxide, and the like, and the dialkyl peroxide group includes dicumyl peroxide, ditertiary butyl peroxide, 2,5- Dimethyl-2,5-ditertiary butyl peroxyhexane, 2,5-dimethyl-2,5-ditertiary butyl peroxyhexine-3 and the like are included, and the diacyl peroxide group includes lauryl peroxide and benzoyl peroxide. Etc. are included. The peroxyester group includes tertiary peroxyacetate, tertiary butyl peroxybenzoate, tertiary butyl peroxyisopropyl carbonate, and the like, and the ketone peroxide group includes cyclohexanone peroxide and the like. Examples of the azo compound include azobisisobutyronitrile and methyl azoisobutyrate. These radical generators may be used alone or in combination of two or more.

  As a commonly used melt extrusion modification operation, the above-mentioned ethylene-vinyl acetate copolymer, unsaturated silane compound, and organic peroxide are blended, blended, and put into a kneader or extruder, and heated, melt-kneaded. The molten resin coming out from the tip die is cooled in a water tank or the like to obtain a silane-modified ethylene-vinyl acetate copolymer.

The blending ratio of the ethylene-vinyl acetate copolymer and the unsaturated silane compound is not particularly limited, but from the viewpoint of the graft modification rate of the unsaturated silane compound described above, a preferred blending range is ethylene-vinyl acetate. The unsaturated silane compound is 1 to 100 parts by mass of the copolymer.
10 parts by mass. If the amount of the unsaturated silane compound is too small relative to the ethylene-vinyl acetate copolymer, the predetermined amount of modification necessary for achieving the effects of the present invention may not be obtained. A large amount of silane compound remains, which may adversely affect performance.

  Although there is no restriction | limiting in particular as a mixing | blending ratio of an unsaturated silane compound and an organic peroxide, As a preferable mixing | blending range, an organic peroxide is 1-10 mass parts with respect to 100 mass parts of unsaturated silane compounds. is there. When the amount of the organic peroxide relative to the unsaturated silane compound is equal to or higher than the lower limit, a sufficient amount of radicals are generated and a necessary predetermined modification amount is easily obtained, and is equal to or lower than the upper limit. And the ethylene-vinyl acetate copolymer tends to be less susceptible to deterioration.

  As melt extrusion modification conditions, for example, in a single screw extruder or a twin screw extruder, it is preferable to extrude at a temperature of about 150 to 250 ° C.

  Moreover, the manufacturing method of the composition for sealing agents of this invention will not be specifically limited if the silane modified body of an ethylene-vinyl acetate copolymer and a silica can be mixed, A silica is used for the silane modified body of an ethylene-vinyl acetate copolymer. Even if it is mixed, silica may be mixed with the raw material mixture when the above unsaturated silane compound is graft-modified to the ethylene-vinyl acetate copolymer, and the composition may be used at the time of graft modification. preferable.

[Physical properties of composition for sealing material]
The melt flow rate (MFR) of the composition for a sealing material of the present invention is preferably 0.1 at a melt flow rate (MFR) at 190 ° C. and a load of 2.16 kg in accordance with JIS K7210 (1999). -30 g / 10 min, more preferably 1-20 g / 10 min. If the MFR is too large, when the element is laminated as a sealing material, the protrusion of the molten resin tends to increase, and it may be difficult to stably seal the element. Moreover, when MFR is too small, there exists a tendency for a bubble to become difficult to escape and it may become easy to generate | occur | produce sealing failure.

[Encapsulant]
The sealing material in this invention is characterized by containing the silane modified body of ethylene-vinyl acetate copolymer, and a silica.

[Method of manufacturing sealing material]
The sealing material of the present invention is obtained by, for example, melting and extruding at a temperature of about 100 to 250 ° C. with an extruder equipped with a T die, and cooling and solidifying according to a normal thermoplastic resin sheet molding method. It is molded with a thickness of about 1.0 mm and is usually a film.

  You may manufacture the sealing material of this invention by carrying out lamination | stacking integration. The method for integrating the layers is not particularly limited. For example, the layer is formed by extrusion laminating a catalyst layer containing a crosslinking agent on one surface of a crosslinked layer containing a silane-modified ethylene-vinyl acetate copolymer and silica. Examples thereof include a method and a method in which a crosslinked layer and a catalyst layer are formed by coextrusion. Especially, it is preferable to form into a film and to laminate | stack simultaneously by a coextrusion process.

  It is preferable that the extrusion setting temperature in the said T-die shaping | molding is 100 to 250 degreeC. When it is at least the lower limit, the appearance is hardly roughened, and when it is at the upper limit or less, a uniform film thickness is easily obtained, and side reactions that cause the appearance are difficult to occur.

[Specific volume resistance]
The specific volume resistance (ρv [Ω · cm]) (conforming to JIS K6271) of the sealing material (film) characterized by containing a modified silane of ethylene-vinyl acetate copolymer and silica is 1.0. × 10 ¹⁴ or more is preferable. When it is at least the lower limit value, a PID phenomenon that is a problem in the solar cell module is unlikely to occur, and the life of the element is likely to be extended.

[Usage]
The encapsulant formed by molding the encapsulant composition in the present invention can be used as an encapsulant for solar cells and light-emitting elements. Therefore, the present invention provides a solar cell comprising the above encapsulant composition. A light emitting element using the battery and the composition for a sealing material is also included. The utilization method for the solar cell and the light emitting element of the composition for a sealing material is in accordance with a known method as a sealing material for a solar cell or a light emitting element. For example, in the case of a solar cell element, it is usually used by being disposed between the solar cell element and the front surface side transparent protective member and / or the back surface side protective member. In the case of a light emitting element, a light emitting element including a first light emitter such as gallium nitride and a second light emitter such as a phosphor is used in a state where the phosphor is dispersed in a sealing material.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist. Further, the values of various production conditions and evaluation results in the following examples have meanings as preferable values of the upper limit or the lower limit in the embodiment of the present invention, and the preferable range is the above-described upper limit or lower limit value. A range defined by a combination of values of the following examples or values of the examples may be used.

〔material〕
In the following examples and comparative examples, the following raw materials were used.

・ EVA-1:
EV250 (Mitsui DuPont Polychemical Co., Ltd., ethylene-vinyl acetate copolymer, MFR: 15 g / 10 min (190 ° C., 2.16 kg load), density: 0.95 g / cm ³ , vinyl acetate (hereinafter abbreviated as VA) Content): 28% by mass, ethylene content: 72% by mass) 100 parts by mass EVA-2:
EV150 (Mitsui DuPont Polychemical Co., Ltd., ethylene-vinyl acetate copolymer, MFR: 30 g / 10 min (190 ° C., 2.16 kg load), density: 0.96 g / cm ³ , VA content: 33% by mass, ethylene Content: 67% by mass) 50 parts by mass and V523 (manufactured by Mitsui DuPont Polychemical Co., Ltd., ethylene-vinyl acetate copolymer, MFR: 15 g / 10 min (190 ° C., 2.16 kg load), density: 0.96 g / cm ³ , VA content: 33% by mass, ethylene content: 67% by mass) 50 parts by mass of mixture / unsaturated silane compound:
KBM1003 (Vinyltrimethoxysilane manufactured by Shin-Etsu Chemical Co., Ltd.)
・ Peroxide:
Perbutyl D (Nitto Corporation Ditertiary Butyl Peroxide)
·silica:
Aerosil (registered trademark) 300 (Fueled silica manufactured by Nippon Aerosil Co., Ltd., specific surface area (300 ± 30) m ² / g (BET method), average primary particle size 7 nm)

[Measurement and evaluation method]
The measurement and evaluation methods for physical properties and characteristics are as follows.

<Melt flow rate (MFR) of composition for sealing material>
Based on JIS K7210 (1999), the measurement was performed at 190 ° C. and a load of 2.16 kg. <Adhesive strength>
The test plate was a glass plate (size: 10 cm × 6 cm × 1 cm), and the test piece (sealing material film) was heated with a 160 ° C. press (20 kg / cm ² ) for 2 minutes to press-bond the test piece to the test plate. . Test environment 23 ° C., 50% RH, test piece (sealing material film) 100 mm × 15 mm × 200 μm, 90 ° C. peel adhesion at a tensile rate of 10 mm / min using a tensile tester (AG-X, manufactured by Shimadzu Corporation) The force was measured. The test plate was washed with acetone before attaching the test piece.

(Total light transmittance / haze)
A sample piece was prepared by sandwiching a sealing material film (thickness: 1.0 mm) by immersing optical oil between two pieces of 2 mm thick white glass (size: 75 mm length, 25 mm width). Using this test piece, total light transmittance was measured according to JIS K7361, and haze was measured according to JIS K7136.

(Inherent volume resistance)
About sealing material film (thickness: 1.0 mm), in accordance with JIS K6271, TR8611A made by ADVANTEST Co. was used, and the specific volume resistance (ρv [Ω ·
cm]).

[Examples and Comparative Examples]
[Example 1]
・ Manufacture of compositions for sealing materials
97.3 parts by mass of EVA-1 as an ethylene-vinyl acetate copolymer, 0.2 parts by mass of silica, 2.4 parts by mass of vinyltrimethoxysilane (KBM1003) as an unsaturated silane compound, and an organic peroxide 0.1 part by weight of perbutyl D was stirred with a blender. After that, it is put into a twin screw extruder (PCM45, manufactured by Ikegai Co., Ltd.) set at a temperature of 220 ° C., and the strand coming out of the nozzle is cooled and solidified in a water tank, and then cut into a pellet shape for sealing material A composition was obtained. Table 1 shows the physical properties of the obtained composition for encapsulant.

Molding of encapsulant film The encapsulant composition produced as described above was melted into a sheet at a die temperature of 150 ° C from an extruder with a screw diameter of 50 mm and L / D28, equipped with a T die with a width of 300 mm. By extruding and cooling, a sealing material film having a thickness of 0.5 mm was formed.

[Example 2, Comparative Examples 1 to 4]
As shown in Table 1, a composition for a sealing material containing a silane-modified ethylene-vinyl acetate copolymer and silica was obtained in the same manner as in Example 1 except that the types of raw materials used and the amounts charged were changed. It was. Further, a sealing material film was formed in the same manner as in Example 1. Each evaluation of the composition for sealing material and the sealing material film was performed in the same manner as in Example 1.

[Evaluation results]
As shown in Table 1, it can be seen that Examples 1 and 2 are good in all values of adhesive strength, total light transmittance, haze and specific volume resistance. Comparative Example 1 is an example in which only an unmodified ethylene-vinyl acetate copolymer was used, but it was found that the adhesive strength was poor. Moreover, although the comparative example 2 is an example which mix | blended the silica with the unmodified ethylene-vinyl acetate copolymer, it turns out that it is inferior to adhesive force and haze. Comparative Examples 3 and 4 are examples in which only the silane-modified ethylene-vinyl acetate copolymer is used without using silica, but the adhesive force is good, but the specific volume resistance is inferior.

  In particular, from the comparison between Comparative Example 1 (without unsaturated silane compound modification) and Comparative Example 3 (with unsaturated silane compound modification), it can be seen that when the ethylene-vinyl acetate copolymer is modified with vinyl silane, the insulating property is lowered. . On the other hand, as is clear from the comparison of Example 1, Comparative Example 1 and Comparative Example 3, in Example 1 in which silica was further added to Comparative Example 3 (with unsaturated silane compound modification), the reduced insulation was improved. In addition, it can be seen that the insulating property is further improved as compared with Comparative Example 1 (unmodified with the unsaturated silane compound).

Claims (7)

The composition for sealing materials characterized by including 0.1-5 mass parts of silica with respect to 100 mass parts of these in total including the silane modified body of ethylene-vinyl acetate copolymer, and silica. The composition for sealing materials of Claim 1 whose said silica is a granular silica with an average primary particle diameter of 0.1-1000 nm.   The composition for sealing materials of Claim 1 or 2 whose melt flow rate (MFR) in 190 degreeC and a 2.16kg load is 0.1-30 g / 10min.   The sealing according to any one of claims 1 to 3, wherein the silane-modified product of the ethylene-vinyl acetate copolymer is obtained by reacting an ethylene-vinyl acetate copolymer with a vinylsilane compound. Material composition.   The sealing material formed by shape | molding the composition for sealing materials of any one of Claims 1 thru | or 4.   The solar cell which uses the composition for sealing materials of any one of Claims 1 thru | or 4. The light emitting element which uses the composition for sealing materials of any one of Claims 1 thru | or 4.