JP2010114118A - Sealing film for solar cell, and solar cell using the same - Google Patents

Abstract

（式中、ｎは３又は４であり、Ｘは、ハロゲン原子、アルキル基、アリール基、アルコキシ基、アリールオキシ基、及びアミノ基よりなる群から選択される少なくとも一種の基を表す）で示されるホスファゼン化合物をさらに含み、
前記ホスファゼン化合物の含有量が、前記エチレン酢酸ビニル共重合体１００質量部に対して、０．１〜３０質量部であることを特徴とする太陽電池用封止膜。
【選択図】なしA sealing film for a solar cell to which flame retardancy is imparted without lowering molding processability and flexibility is provided.
A sealing film for a solar cell comprising an ethylene vinyl acetate copolymer and an organic oxide,
Following formula (1)
[Chemical 1]

(Wherein n represents 3 or 4, and X represents at least one group selected from the group consisting of a halogen atom, an alkyl group, an aryl group, an alkoxy group, an aryloxy group, and an amino group) Further comprising a phosphazene compound,
Content of the said phosphazene compound is 0.1-30 mass parts with respect to 100 mass parts of said ethylene vinyl acetate copolymers, The sealing film for solar cells characterized by the above-mentioned.
[Selection figure] None

Description

  The present invention relates to a solar cell sealing film imparted with flame retardancy.

  In recent years, solar cells that convert sunlight into electrical energy have attracted attention and are being developed from the viewpoint of effective use of resources and prevention of environmental pollution.

  As shown in FIG. 1, a solar cell generally includes a front surface side transparent protective member 11 made of a glass substrate or the like, a front surface side sealing film 13 </ b> A, a silicon power generation element 14, a back surface side sealing film 13 </ b> B, and a back surface side protective member ( The back cover) 12 is laminated in this order, degassed under reduced pressure, and then heated and pressurized to crosslink and cure the front side sealing film 13A and the back side sealing film 13B to be bonded and integrated. In a conventional solar cell, a plurality of power generation elements 14 are connected and used in order to obtain a high electric output. Therefore, the solar cell is sealed using the sealing films 13A and 13B having insulating properties. Thereby, it is possible to prevent electricity leakage inside the solar cell and reliably extract the generated electricity via the wiring.

  As a sealing film used for a solar cell, for example, an ethylene vinyl acetate copolymer (EVA) film or the like is used. An EVA film is produced by forming a film by subjecting a composition containing EVA, a crosslinking agent, and the like to heat rolling by, for example, extrusion molding. Thus, in EVA film, in order to improve film | membrane intensity | strength and durability, crosslinking structures are provided to EVA using crosslinking agents, such as an organic peroxide.

  Solar cells are attached to a building such as a roof of a house and used outdoors. Therefore, it is desirable that the flammability of the solar cell is low when used by being attached to a building. For this reason, attempts have been made to impart flame retardancy to EVA films used as sealing films.

  Patent Document 1 discloses an EVA film to which a flame retardant is added. Examples of the flame retardant include halogen-based organic flame retardant having a halogen atom, and inorganic flame retardants such as aluminum hydroxide and magnesium hydroxide.

JP 09-27633 A

  The halogen-based organic flame retardant can impart high flame retardancy to the EVA film. However, in recent years, halogen-based organic flame retardants may generate a large amount of dioxin-based compounds during combustion decomposition, and are considered as substances that have a harmful effect on the environment, and the use of halogen-based organic flame retardants is also restricted.

  In addition, an inorganic flame retardant such as magnesium hydroxide needs to be added in a large amount in order to impart sufficient flame retardancy to the EVA film. However, it is difficult to sufficiently mix a large amount of the inorganic flame retardant and EVA, the molding processability is low, the hardness of the obtained EVA film is increased, and the power generation element may be damaged. The sealing film is required to have appropriate flexibility in order to suppress damage to the power generation element.

  Therefore, the objective of this invention is providing the sealing film for solar cells to which the flame retardance was provided, without reducing a moldability and a softness | flexibility.

  As a result of various studies in view of the above problems, the present inventors have found that the above problems can be solved by using a phosphazene compound having a specific structure as a flame retardant with a specific content.

That is, the present invention is an encapsulating film for solar cells containing an ethylene vinyl acetate copolymer and an organic oxide,
Following formula (1)

（式中、ｎは３又は４であり、Ｘは、ハロゲン原子、アルキル基、アリール基、アルコキシ基、アリールオキシ基、又はアミノ基を表す）で示されるホスファゼン化合物をさらに含み、
前記ホスファゼン化合物の含有量が、前記エチレン酢酸ビニル共重合体１００質量部に対して、０．１〜３０質量部であることを特徴とする太陽電池用封止膜により、上記課題を解決する。

(Wherein n represents 3 or 4, and X represents a halogen atom, an alkyl group, an aryl group, an alkoxy group, an aryloxy group, or an amino group), and further includes a phosphazene compound represented by:
The above problem is solved by a sealing film for solar cells, wherein the content of the phosphazene compound is 0.1 to 30 parts by mass with respect to 100 parts by mass of the ethylene vinyl acetate copolymer.

  The sealing film for solar cells of the present invention is imparted with flame retardancy by the phosphazene compound. Furthermore, by setting the content of the phosphazene compound within a specific range, it becomes possible to impart flame retardancy without reducing molding processability and flexibility. Further, the phosphazene compound is an inorganic compound even if it contains a halogen atom, and thus has little influence on the environment. Therefore, according to such a sealing film for solar cells, it is possible to provide a solar cell with low combustibility without fear of damaging the power generating element or the like.

  The solar cell sealing film of the present invention contains an ethylene vinyl acetate copolymer, an organic oxide, and a phosphazene compound as basic components.

  The phosphazene compound is used as a flame retardant for imparting flame retardancy to the solar cell sealing film. The phosphazene compound specifically includes the following formula (1):

（式中、ｎは３又は４であり、Ｘは、ハロゲン原子、アルキル基、アリール基、アルコキシ基、アリールオキシ基、又はアミノ基を表す）で示される。

(Wherein n represents 3 or 4, and X represents a halogen atom, an alkyl group, an aryl group, an alkoxy group, an aryloxy group, or an amino group).

  In the formula (1), Xs may be the same or different from each other.

  Examples of the halogen atom include a fluorine atom, a bromine atom, and an iodine atom.

  As said alkyl group, a C1-C10, especially 1-6 alkyl group is preferable. Examples thereof include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an s-butyl group, a tert-butyl group, an n-amyl group, and an isoamyl group.

  The aryl group is preferably an aryl group having 6 to 11 carbon atoms. The aryl group may be substituted with an alkyl group having 1 to 6 carbon atoms. Examples of the aryl group include a phenyl group, 2-methylphenyl group, 3-methylphenyl group, 4-methylphenyl group, 2,6-dimethylphenyl group, 3,5-dimethylphenyl group, and 2,5-dimethylphenyl. Group, 2,4-dimethylphenyl group, 3,4-dimethylphenyl group and the like.

  As said alkoxy group, a C1-C10, especially 1-6 alkoxy group is preferable. Examples thereof include a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a butoxy group, a sec-butoxy group, an isobutoxy group, and a t-butoxy group.

  As said aryloxy group, a C1-C10 aryloxy group is preferable, for example, a phenoxy group, a naphthoxy group, an anthracenoxy group etc. are mentioned. Moreover, the aryloxy group may have a substituent in the aryl part. As the substituent, an alkyl group having 1 to 6 carbon atoms is preferable.

  In the formula (1), n is preferably 3, that is, the following formula (2)

（式中、Ｘ₁〜Ｘ₆は、上記式（１）におけるＸと同義である）で示されるホスファゼン化合物が好ましい。

A phosphazene compound represented by the formula (wherein X _{1 to} X ₆ have the same meaning as X in the formula (1)) is preferred.

In the formula (2), X _{1 to} X ₆ are each a halogen atom, an alkoxy group, or an aryloxy group, and particularly preferably a fluorine atom, a phenoxy group, an ethoxy group, or a methoxy group.

  The content of the phosphazene compound in the solar cell sealing film is 0.1 to 30 parts by mass, preferably 1.0 to 20 parts by mass, more preferably 10 to 10 parts by mass with respect to 100 parts by mass of the ethylene vinyl acetate copolymer. 20 parts by mass. With such a content, mixing of the phosphazene compound and EVA is easy, and the molding processability of the sealing film is not lowered. Moreover, since the obtained sealing film does not have too high hardness and has appropriate flexibility, it is possible to suppress damage to the power generation element and the like.

  The sealing film for solar cells of the present invention contains an ethylene vinyl acetate copolymer. The content of vinyl acetate in the ethylene vinyl acetate copolymer is 20 to 35 parts by mass, more preferably 22 to 30 parts by mass, and particularly 24 to 28 parts by mass with respect to 100 parts by mass of the ethylene vinyl acetate copolymer. preferable. If the vinyl acetate content is less than 20 parts by mass, the transparency of the sealing film obtained when crosslinked and cured at high temperatures may not be sufficient, and if it exceeds 35 parts by mass, the hardness of the resulting sealing film May be too low.

  The solar cell sealing film of the present invention contains an organic peroxide as a crosslinking agent. Thereby, the crosslinked cured film of EVA can be obtained and the sealing property of a solar cell and a flame retardance can be improved.

  Any organic peroxide may be used as long as it decomposes at a temperature of 100 ° C. or higher and generates radicals. The organic peroxide is generally selected in consideration of the film formation temperature, the adjustment conditions of the composition, the curing temperature, the heat resistance of the adherend, and the storage stability. In particular, the one having a decomposition temperature of 70 ° C. or more with a half-life of 10 hours is preferable.

  Examples of the organic peroxide include t-butyl peroxyisopropyl carbonate, t-butyl peroxy-2-ethylhexyl carbonate, 2,5-dimethylhexane-2,5 from the viewpoint of processing temperature and storage stability of the resin. -Dihydroperoxide, 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane, di-t-hexyl peroxide, t-butylcumyl peroxide, di-t-butyl peroxide, 2 , 5-Dimethyl-2,5-di (t-butylperoxy) hexane, dicumyl peroxide, α, α'-bis (t-butylperoxyisopropyl) benzene, n-butyl-4,4-bis ( t-butylperoxy) valerate, 2,2-bis (t-butylperoxy) butane, 1,1-bis (t-butylpero) C) Cyclohexane, 1,1-bis (t-butylperoxy) trimethylcyclohexane, 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, t-butylperoxybenzoate, benzoylper Oxide, t-butyl peroxyacetate, methyl ethyl ketone peroxide, 2,5-dimethyl-2,5-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, 1,1-bis (t-butyl) Peroxy) cyclohexane, methyl ethyl ketone peroxide, 2,5-dimethylhexyl-2,5-bisperoxybenzoate, t-butyl hydroperoxide, p-menthane hydroperoxide, p-chlorobenzoyl peroxide, hydroxyheptyl peroxide , Chlorohexanone peroxide, octanoyl peroxide, decanoyl peroxide, lauroyl peroxide, cumylperoxy octoate, succinic acid peroxide, acetyl peroxide, t-butylperoxy (2-ethylhexanoate), m- Mention may be made of toluoyl peroxide, t-butyl peroxyisobutylene and 2,4-dichlorobenzoyl peroxide. An organic peroxide may be used individually by 1 type, and may be used in combination of 2 or more type.

  As the organic peroxide, it is preferable to use a dialkyl peroxide organic peroxide. Since such an organic peroxide is not easily decomposed even when energy such as ultraviolet rays or heat is applied, the durability of the resulting solar cell sealing film can be further improved.

  Examples of dialkyl peroxide organic peroxides include α, α′-bis (t-butylperoxyisopropyl) benzene, dicumyl peroxide, di-t-hexyl peroxide, 2,5-dimethyl-2,5- Examples include di (t-butylperoxy) hexane, t-butylcumyl peroxide, and di-t-butylperoxide.

  The content of the organic peroxide in the solar cell sealing film is preferably 0.1 to 2.5 parts by mass, more preferably 0.5 to 2.1, with respect to 100 parts by mass of the ethylene vinyl acetate copolymer. 0 parts by mass. When the content of the organic peroxide is within the above range, a sealing film having excellent molding processability can be obtained.

  It is preferable that the sealing film for solar cells of the present invention further contains a crosslinking aid. A crosslinking aid can improve the gel fraction of EVA and can improve sealing performance and flame retardancy. As a crosslinking aid (compound having a radical polymerizable group as a functional group) provided for this purpose, in addition to a trifunctional crosslinking aid such as triallyl cyanurate and triallyl isocyanurate, (meth) acrylic ester ( Examples thereof include monofunctional or bifunctional crosslinking aids such as NK ester. Of these, triallyl cyanurate and triallyl isocyanurate are preferable, and triallyl isocyanurate is particularly preferable.

  The content of the crosslinking aid in the solar cell sealing film is preferably 5 parts by mass or less, more preferably 0.1 to 5.0 parts by mass with respect to 100 parts by mass of EVA.

  The sealing film for solar cells is used to improve or adjust various physical properties (optical properties such as mechanical strength, adhesiveness and transparency, heat resistance, light resistance, crosslinking speed, etc.), especially for improving mechanical strength. If necessary, it may further contain a plasticizer, an adhesion improver, an acryloxy group-containing compound, a methacryloxy group-containing compound, an epoxy group-containing compound, and the like.

  The plasticizer is not particularly limited, but polybasic acid esters and polyhydric alcohol esters are generally used. Examples thereof include dioctyl phthalate, dihexyl adipate, triethylene glycol-di-2-ethylbutyrate, butyl sebacate, tetraethylene glycol diheptanoate, and triethylene glycol dipelargonate. One type of plasticizer may be used, or two or more types may be used in combination. The content of the plasticizer is preferably in the range of 5 parts by mass or less with respect to 100 parts by mass of EVA.

  As the adhesion improver, a silane coupling agent can be used. Thereby, it becomes possible to form the sealing film for solar cells which has the outstanding adhesive force. Examples of the silane coupling agent include γ-chloropropylmethoxysilane, vinylethoxysilane, vinyltris (β-methoxyethoxy) silane, γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, and γ-glycidoxypropyltrimethoxy. Silane, γ-glycidoxypropyltriethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, vinyltrichlorosilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β Mention may be made of-(aminoethyl) -γ-aminopropyltrimethoxysilane. These silane coupling agents may be used alone or in combination of two or more. Moreover, it is preferable that content of the said adhesive improvement agent is 5 mass parts or less with respect to 100 mass parts of EVA.

  The acryloxy group-containing compound and the methacryloxy group-containing compound are generally acrylic acid or methacrylic acid derivatives, and examples thereof include acrylic acid or methacrylic acid esters and amides. Examples of ester residues include linear alkyl groups such as methyl, ethyl, dodecyl, stearyl, lauryl, cyclohexyl group, tetrahydrofurfuryl group, aminoethyl group, 2-hydroxyethyl group, 3-hydroxypropyl group. Group, 3-chloro-2-hydroxypropyl group. Examples of amides include diacetone acrylamide. In addition, polyhydric alcohols such as ethylene glycol, triethylene glycol, polypropylene glycol, polyethylene glycol, trimethylolpropane, and pentaerythritol, and esters of acrylic acid or methacrylic acid can also be used.

Examples of the epoxy-containing compound include triglycidyl tris (2-hydroxyethyl) isocyanurate, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, allyl glycidyl ether, 2-ethylhexyl glycidyl ether, phenyl glycidyl ether, Examples include phenol (ethyleneoxy) ₅ glycidyl ether, pt-butylphenyl glycidyl ether, adipic acid diglycidyl ester, phthalic acid diglycidyl ester, glycidyl methacrylate, and butyl glycidyl ether.

  The acryloxy group-containing compound, the methacryloxy group-containing compound, or the epoxy group-containing compound is generally 0.5 to 5.0 parts by mass, particularly 1.0 to 4.0 parts by mass, respectively, with respect to 100 parts by mass of EVA. It is preferable that

  Furthermore, the solar cell sealing film of the present invention may contain a light stabilizer and / or an anti-aging agent.

  By including the light stabilizer in the solar cell sealing film, it is possible to suppress the deterioration of EVA due to the influence of irradiated light and the like, and the solar cell sealing film to be yellowed. As the light stabilizer, a light stabilizer called a hindered amine type is preferably used. For example, LA-52, LA-57, LA-62, LA-63LA-63p, LA-67, LA-68 (all ( ADEKA Co., Ltd.), Tinuvin 744, Tinuvin 770, Tinuvin 765, Tinuvin 144, Tinuvin 622LD, CHIMASORB 944LD (all manufactured by Ciba Specialty Chemicals Co., Ltd.), UV-3034 (BF Goodrich) Can be mentioned. In addition, the said light stabilizer may be used individually or may be used in combination of 2 or more types, and it is preferable that the compounding quantity is 0.01-5 mass parts with respect to 100 mass parts of EVA.

  Examples of the antioxidant include hindered phenol antioxidants such as N, N′-hexane-1,6-diylbis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionamide]. , Phosphorus heat stabilizers, lactone heat stabilizers, vitamin E heat stabilizers, sulfur heat stabilizers, and the like.

  Although the thickness in particular of the sealing film for solar cells is not restrict | limited, What is necessary is just the range of 50 micrometers-2 mm.

  What is necessary is just to perform according to a well-known method in order to form the sealing film for solar cells of this invention mentioned above. For example, it is produced by a method of obtaining a sheet-like material by molding a composition containing the above-described various components such as EVA, an organic oxide, and a phosphazene compound by ordinary extrusion molding or calendering. be able to. Alternatively, a sheet-like material can be obtained by dissolving the composition in a solvent and coating the solution on a suitable support with a suitable coating machine (coater) and drying to form a coating film. When a film is formed by heat rolling using extrusion molding or the like, heating is generally in the range of 50 to 90 ° C.

  The structure of the solar cell using the solar cell sealing film of the present invention is not particularly limited, but is crosslinked by interposing the solar cell sealing film between the front surface side transparent protective member and the back surface side protective member. For example, a structure in which the power generation element is sealed by integrating the power generation element may be used.

  In the solar cell, in order to sufficiently seal the power generation element, as shown in FIG. 1, the front surface side transparent protective member 11, the front surface side sealing film 13A, the power generation element 14, the back surface side sealing film 13B, and the back surface side protection. The member 12 may be laminated and the sealing film may be cross-linked and cured according to a conventional method such as heat and pressure.

In order to heat and pressurize, for example, the laminate is heated with a vacuum laminator at a temperature of 135 to 180 ° C., further 140 to 180 ° C., particularly 155 to 180 ° C., a degassing time of 0.1 to 5 minutes, and a press pressure of 0.1 What is necessary is just to heat-press in about 1.5 kg / cm < ² > and press time 5-15 minutes. At the time of this heating and pressurizing, the EVA contained in the front side sealing film and the rear side sealing film is cross-linked, whereby the front side transparent protective member, the rear side, through the front side sealing film and the rear side sealing film. The power generation element can be sealed by integrating the transparent member and the power generation element.

  In the present invention, the side of the solar cell irradiated with light is referred to as “front side”, and the side opposite to the light receiving surface of the solar cell is referred to as “back side”.

  The above-described solar cell sealing film of the present invention is preferably used at least as a back surface side sealing film, and particularly preferably used as both a front surface side sealing film and a back surface side sealing film. The back surface side sealing film means a sealing film disposed between the power generation element and the back surface side protection member, and the front surface side sealing film is disposed between the power generation element and the surface side transparent protection member. It means a sealing film.

  The surface side transparent protective member used for the solar cell of the present invention is usually a glass substrate such as silicate glass. As for the thickness of a glass substrate, 0.1-10 mm is common, and 0.3-5 mm is preferable. The glass substrate may generally be chemically or thermally strengthened.

  The back surface side protective member used in the present invention is a plastic film such as PET. In consideration of heat resistance and moist heat resistance, a fluorinated polyethylene film, particularly a fluorinated polyethylene film / Al / fluorinated polyethylene film, in this order. A film laminated with is preferable.

  In addition, the solar cell of this invention has the characteristics in the sealing film used for the surface side and a back surface side as above-mentioned. Therefore, members other than the sealing film such as the front surface side transparent protective member, the back surface side protective member, and the power generation element are not particularly limited as long as they have the same configuration as that of a conventionally known solar cell.

  Hereinafter, the present invention will be described with reference to examples. The present invention is not limited by the following examples.

Example 1
A solar cell sealing film (thickness: 1.0 mm) was formed by a calendar molding method using the following composition as a raw material. The blend was kneaded at 80 ° C. for 15 minutes, the calender roll temperature was 80 ° C., and the processing speed was 5 m / min.

Formulation;
EVA (vinyl acetate content 24 parts by mass with respect to EVA 100 parts by mass, Tosoh Corporation Ultrasen 640) 100 parts by mass,
1.5 parts by mass of a crosslinking agent (2,5-dimethyl-2,5-bis (t-butylperoxy) hexane),
1.5 parts by mass of a crosslinking aid (triallyl isocyanate),
Phosphazene compound (1) (X ₁ in the above formula (2) is a phenoxy group and X _{2 to} X ₆ are fluorine atoms; Phoslite (registered trademark) -O, manufactured by Bridgestone Corporation) 1.0 part by mass.

(Examples 2 to 4)
In Examples 2 to 4, a solar cell sealing film was produced in the same manner as in Example 1 except that the blending amount of the phosphazene compound (1) was 5 parts by mass, 10 parts by mass, and 20 parts by mass, respectively. did.

(Examples 5-7)
In Examples 5 to 7, instead of the phosphazene compound (1), the phosphazene compound (2) (X ₁ and X ₃ in the above formula (2) are ethoxy groups, and X ₂ and X _{4 to} X ₆ are fluorine atoms. ; Phoslite (registered trademark) -D, manufactured by Bridgestone Corporation) was used in the same manner as in Example 1 except that 5.0 parts by mass, 10 parts by mass, and 20 parts by mass were used, respectively. Produced.

(Examples 8 to 10)
In Examples 8 to 10, in place of the phosphazene compound (1), the phosphazene compound (3) (X ₁ in the above formula (2) is an ethoxy group, and X _{2 to} X ₆ are fluorine atoms; (Trademark) -E, manufactured by Bridgestone Corporation) was used in the same manner as in Example 1 except that 5.0 parts by mass, 10 parts by mass, and 20 parts by mass were used, respectively, to prepare a solar cell sealing film.

(Example 11)
In Example 11, instead of the phosphazene compound (1), the phosphazene compound (4) (n in the above formula (1) is 3, and X is a phenoxy group; FP100, manufactured by Fushimi Pharmaceutical Co., Ltd.) 10 mass A solar cell sealing film was produced in the same manner as in Example 1 except that the part was used.

Example 12
In Example 12, in place of the phosphazene compound (1), the phosphazene compound (5) (X ₁ , X ₃ and X ₅ in the above formula (2) are methoxy groups, and X ₂ , X ₄ and X ₆ are phenoxy. It was carried out in the same manner as in Example 1 except that 10 parts by mass of FP3006 (Fushimi Pharmaceutical Co., Ltd.) was used to produce a solar cell sealing film.

(Comparative Example 1)
A solar cell sealing film was prepared in the same manner as in Example 1 except that the phosphazene compound (1) was not used.

(Comparative Examples 2 and 3)
In Comparative Examples 2 and 3, solar cell sealing films were prepared in the same manner as in Example 1 except that the blending amounts of the phosphazene compound (1) were 25 parts by mass and 0.005 parts by mass, respectively.

  In Comparative Example 2, it was difficult to knead the composition and molding was not possible, and a solar cell sealing film could not be obtained.

(Comparative Examples 4-6)
In Comparative Examples 4 to 6, Example 1 was used except that 10 parts by mass, 20 parts by mass, and 100 parts by mass of aluminum hydroxide (Hidilite H43M Showa Denko KK) were used instead of the phosphazene compound (1). In the same manner as described above, a solar cell sealing film was produced.

  In addition, the sealing film obtained in Comparative Example 7 had an excessively high hardness and was unsuitable for a solar cell sealing film.

(Evaluation)
The solar cell sealing films prepared in Examples and Comparative Examples were cured according to the following procedure, and then subjected to a horizontal combustion test.

  The sealing film for solar cells was placed in an oven and heated at 155 ° C. for 45 minutes to crosslink EVA.

  The horizontal combustion test was conducted in accordance with UL94 HB standard. The solar cell sealing film after crosslinking was cut into a strip shape (width 1.3 cm, length 12.5 cm), and the burning length and burning speed between 25 mm and 100 mm marked lines were measured. The results are shown in Tables 1 and 2.

  From Tables 1 and 2, it can be seen that the sealing film for solar cells of the present invention has a short combustion length and a low combustion rate, so that flame retardancy is improved. Moreover, although the sealing film for solar cells of Comparative Example 7 also has improved combustibility, since it has high hardness, it may cause damage to the power generating element when used in a solar cell. On the other hand, the sealing film for solar cells of the present invention is suitably used for solar cells without deterioration of molding processability and flexibility.

It is explanatory drawing of a common solar cell.

Explanation of symbols

11 surface side transparent protective member,
12 Back side protection member,
13A surface side sealing film,
13B Back side sealing film,
14 Power generation element.

Claims (6)

A sealing film for solar cells comprising an ethylene vinyl acetate copolymer and an organic oxide,
Following formula (1)

(Wherein n represents 3 or 4, and X represents a halogen atom, an alkyl group, an aryl group, an alkoxy group, an aryloxy group, or an amino group), and further includes a phosphazene compound represented by:
Content of the said phosphazene compound is 0.1-30 mass parts with respect to 100 mass parts of said ethylene vinyl acetate copolymers, The sealing film for solar cells characterized by the above-mentioned.   2. The solar cell seal according to claim 1, wherein the content of the organic oxide is 0.1 to 2.5 parts by mass with respect to 100 parts by mass of the ethylene vinyl acetate copolymer. Stop film.   The solar cell sealing film according to claim 1, further comprising a crosslinking aid.   4. The solar cell sealing according to claim 3, wherein the content of the crosslinking aid is 0.1 to 5.0 parts by mass with respect to 100 parts by mass of the ethylene vinyl acetate copolymer. film. A solar cell formed by sealing a power generation element by interposing a sealing film between a front surface side transparent protective member and a back surface side protective member and integrating them together,
The solar cell, wherein the sealing film disposed between the power generation element and the back surface side protective member is the solar cell sealing film according to claim 1. .   The sealing film arrange | positioned between the said electric power generation element and the said surface side transparent protective member is a sealing film for solar cells described in any one of Claims 1-5. Item 6. The solar cell according to Item 5.

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