JP2001036116A - Solar battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solar battery which can be used interchangeably as a roof material, using a back-side protecting member which has enhanced fire retardancy and incombustibility, without damaging the adhesion of an EVA film. SOLUTION: This solar battery is prepared by sealing solar battery cells between a surface transparent protecting member and a rear protecting member 10. The member 10 is prepared by integrally laminating a PET film 11 and a zinc steel plate 12 via an EVA film 13, and a sealing film and/or the film 13 is made flame retardant and contains an EVA film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solar cell using an ethylene-vinyl acetate copolymer resin (EVA) film, and more particularly to a method for solving the problem of flammability of an EVA film and significantly improving the flame retardancy. Related to solar cells.

[0002]

2. Description of the Related Art In recent years, solar cells which directly convert sunlight into electric energy have been attracting attention from the viewpoints of effective use of resources and prevention of environmental pollution, and their development has been promoted.

As shown in FIG. 2, a solar cell generally has an EVA film sealing film 3 between a transparent substrate 1 such as a glass substrate as a front transparent protective member and a rear protective member 2.
The solar cell such as the silicon power generation element 4 is sealed by A and 3B. This back side protection member 2
In recent years, polyethylene terephthalate (PET) films have been used in place of glass in order to reduce weight and thickness. In the following, the sealing film disposed on the light receiving surface side of the cell is referred to as “front side sealing film”, and the sealing film disposed on the rear side of the cell is referred to as “back side sealing film”.

Such a solar cell comprises a transparent substrate 1, a front-side sealing film 3A, a silicon power generation element 4, and a back-side sealing film 3B.
The back side protective member 2 is laminated in this order, and heated and pressurized to crosslink and harden the EVA to be bonded and integrated.

However, since solar cells are expensive at present, arranging solar cells on a roofing material increases the cost. Therefore, in order to reduce the construction cost, the solar cells are replaced with the roofing material. It is considered that the solar cell itself is used as a roofing material, and the cost is suppressed by omitting the roofing material instead of disposing the solar cell on the roofing material.

[0006]

SUMMARY OF THE INVENTION However, EVA
The laminate of the film and the PET film has a drawback that the EVA is heated during the burning of the solar cell and is dropped and burned, so that it cannot be directly used as a roofing material.

[0007] The present invention solves the above-mentioned conventional problems and provides an EV.
An object of the present invention is to provide a solar cell which can be used as a roofing material, using a back side protective member having flame retardancy or non-combustibility without impairing the adhesiveness of the A film.

[0008]

According to the present invention, there is provided a solar cell comprising a solar cell sealed with a sealing film between a front-side transparent protective member and a rear-side protective member.
The back side protection member is formed by laminating and integrating a resin film, an EVA film, and a zinc steel plate, and is formed of a sealing film interposed between the front side transparent protection member and the solar cell. 1 or 2 of the EVA film used for the sealing film interposed between
The above is a feature of the EVA film to which the flame retardant is added.

In the case of a solar cell using such a back side protective member and an EVA film containing a flame retardant, extremely good flame retardancy and non-flammability can be ensured by the zinc steel sheet and the flame retardant in the EVA film. . Although the light transmittance is reduced by using the zinc steel sheet, in the present invention, since the zinc steel sheet is used for the back surface side protection member, there is no problem that the power generation efficiency of the solar cell is reduced due to the reduced light transmittance.

In the present invention, the zinc steel sheet has a thickness of 15 to
A steel sheet having a thickness of 1 to 10 μm is preferably formed on a surface of a 100 μm steel sheet. Further, the EVA film preferably has a thickness of 5 to 600 μm.

Further, a PET film is preferred as the resin film.

As the flame retardant, an organic flame retardant containing at least one halogen atom such as a chlorine atom or a bromine atom in a molecule, or an inorganic flame retardant such as an inorganic hydroxide salt, a phosphor oxide, or a red phosphorus is used. And, if necessary, a flame retardant aid such as antimony trioxide and expanded graphite. EVA constituting the EVA film preferably has a crosslinked structure.

[0013]

Embodiments of the present invention will be described below in detail with reference to the drawings.

First, a back side protection member according to the present invention will be described with reference to FIG.

FIGS. 1A to 1C are cross-sectional views showing an embodiment of a back side protective member according to the present invention.

As shown in the figure, a back side protective member 10 according to the present invention is provided between a PET film 11 and a zinc steel plate 12.
If necessary, it is laminated and integrated with an EVA film 13 containing a flame retardant interposed therebetween.

The zinc steel plate 12 used here has a thickness of 15 to
A steel plate having a thickness of 1 to 10 μm is preferably formed on the front and back surfaces of a 100 μm steel plate.

The PET film 11 has a thickness of 5
A film having a thickness of about 0 to 600 μm is preferable, and a film having a thickness of 5 to 600 μm is preferably used as the EVA film 13 in order to secure the adhesiveness and to obtain the effect of improving the flame retardancy and nonflammability of the zinc steel sheet.

Such a back side protective member 10 is easily manufactured by laminating a PET film 11 and a zinc steel plate 12 via an EVA film 13 by coating or calendering, and by bonding or temporary bonding. be able to.

As shown in FIG. 1B, the back side protective member according to the present invention further comprises a PET film 15 laminated on the zinc steel sheet 12 via an EVA film 14 to form a back side of the five-layer laminated film. The protection member 10A may be used. Further, as shown in FIG. 1C, a back side protection member 10B in which a coating film 16 of acrylic, polyester, epoxy, fluorine-based paint or the like is formed on the surface of a zinc steel plate 12 may be used.

In order to manufacture the solar cell of the present invention using such a back side protective member, as shown in FIG. 2, a transparent substrate 1, a sealing film 3A, a silicon power generating element 4, a sealing film 3B and a back surface When laminating the side protection member 2, the back side protection member 2
As, using the back side protection member according to the present invention, laminated so that the zinc steel sheet 12 side is the back side, according to a conventional method, a vacuum laminator at a temperature of 120 to 150 ° C., a deaeration time of 2 to 15 minutes, Press pressure 0.5-1kg / cm ² ,
What is necessary is just to heat and press-press and integrate by pressing time 8 to 45 minutes.

Here, as the sealing films 3A and 3B, it is preferable to use an EVA film having a thickness of about 5 to 600 μm as in the prior art. In the present invention, the back surface of the EVA film constituting the front-side sealing film is preferred. EVA Film Constituting Side Sealing Film An EVA film containing a flame retardant is used as at least one EVA film among the EVA films as an adhesive film for the back surface side protective member.

In the present invention, PET film / EVA
Film / zinc steel sheet three-layer laminated backside protective member and EV
A remarkably good flame retardancy and non-flammability can be obtained by the flame retardant added to the A film.
A high degree of fire resistance is not required. Therefore, since the back side protective member of this three-layer structure has an increase in weight of the zinc steel plate as compared with the ordinary PET film, from the viewpoint of preventing the weight increase of the entire solar cell, the front side transparent substrate 1 is used. In place of the glass plate, a light-weight transparent resin plate such as polycarbonate or acrylic may be used.

Hereinafter, EVA and a flame retardant suitable as a raw material for forming an EVA film used as an adhesive film of the sealing film and the back surface side protective member in the present invention will be described.

The EVA used in the present invention has a vinyl acetate content of 10 to 50% by weight, especially 15 to 40% by weight,
Melt flow rate is 0.7-20, especially 1.5-10
It is preferable that

The EVA used in the present invention is preferably blended with a cross-linking agent to improve the weather resistance and to have a cross-linked structure. The cross-linking agent is generally an organic compound which generates radicals at 100 ° C. or higher. A peroxide is used, and in particular, in consideration of the stability at the time of blending, those having a decomposition temperature of 70 ° C. or more with a half-life of 10 hours are preferable. Examples of such an organic peroxide include 2,5-dimethylhexane; 2,5-dihydroperoxide; 2,5-dimethyl-2,5-di (t-butylperoxy) hexane;
3-di-t-butyl peroxide; t-dicumyl peroxide; 2,5-dimethyl-2,5-di (t-butylperoxy) hexine; dicumyl peroxide;
α, α'-bis (t-butylperoxyisopropyl)
Benzene; n-butyl-4,4-bis (t-butylperoxy) butane; 2,2-bis (t-butylperoxy) butane; 1,1-bis (t-butylperoxy) cyclohexane; 1-bis (t-butylperoxy)
3,3,5-trimethylcyclohexane; t-butylperoxybenzoate; benzoyl peroxide and the like can be used. The amount of these organic peroxides is generally 5 parts by weight or less based on 100 parts by weight of EVA.
Preferably, it is 1 to 3 parts by weight.

As a sealing film for a solar cell, a silane coupling agent can be added to EVA for the purpose of improving adhesion to a power generating element or the like. Known silane coupling agents for this purpose include, for example, γ-chloropropyltrimethoxysilane; vinyltrichlorosilane; vinyltriethoxysilane; vinyl-tris- (β
-Methoxyethoxy) silane; γ-methacryloxypropyltrimethoxysilane; β- (3,4-ethoxycyclohexyl) ethyltrimethoxysilane; γ-glycidoxypropyltrimethoxysilane; vinyltriacetoxysilane; γ-mercaptopropyltri Methoxysilane; γ-aminopropyltrimethoxysilane; N-β-
And (aminoethyl) -γ-aminopropyltrimethoxysilane. The amount of these silane coupling agents is generally 5 parts by weight or less, preferably 0.1 to 2 parts by weight, based on 100 parts by weight of EVA.

Further, a crosslinking assistant can be added to EVA in order to improve the gel fraction of EVA and improve durability. Examples of the crosslinking aid used for this purpose include trifunctional crosslinking aids such as triallyl isocyanurate and triallyl isocyanate as well as monofunctional crosslinking aids such as NK esters. it can. The amount of these crosslinking aids is generally 10 parts by weight or less, preferably 1 to 5 parts by weight, based on 100 parts by weight of EVA.

Further, for the purpose of improving the stability of EVA, hydroquinone; hydroquinone monomethyl ether;
-Benzoquinone; methylhydroquinone and the like can be added, and the blending amount thereof is generally 5 parts by weight or less based on 100 parts by weight of EVA.

Further, if necessary, a coloring agent, an ultraviolet absorber, an antioxidant, a discoloration inhibitor and the like can be added in addition to the above. Examples of the coloring agent include inorganic pigments such as metal oxides and metal powders, and organic pigments such as azo-based, phthalocyanine-based, azo-based, acidic or basic dye-based lakes. UV absorbers include 2-hydroxy-4-octoxybenzophenone; benzophenones such as 2-hydroxy-4-methoxy-5-sulfobenzophenone; 2- (2'-hydroxy-5-methylphenyl) benzotriazole; Benzotriazoles; phenyl salicylate; pt-
There are hindered amines such as butylphenyl salicylate. As anti-aging agents, amines; phenols;
Bisphenyl type; hindered amine type, for example, di-t-butyl-p-cresol; bis (2,2,6,6
-Tetramethyl-4-piperazyl) sebacate.

Examples of the flame retardant added to the EVA include an organic flame retardant and an inorganic flame retardant containing at least one halogen atom, preferably a chlorine atom or a bromine atom in a molecule.

Here, examples of the organic flame retardant include chlorinated paraffin, chlorinated polyethylene, hexachloroendomethylenetetrahydrophthalic acid, perchloropentacyclodecane, phthalic anhydride tetrachloride and the like, and tris (2, 2).
A monomer or polymer having an aromatic ring such as (3-dibromopropyl) isocyanurate and having no halogen atom directly bonded to the aromatic ring, 1,1,2,2-tetrabromoethane, 1,4-dibromobutane , 1,3-dibromobutane, 1,5-dibromopentane, ethyl α-bromobutyrate, 1,2,5,6,9,10-hexabromocyclodecane and the like having no aromatic ring.

Examples of inorganic flame retardants include inorganic hydroxides such as aluminum hydroxide and magnesium hydroxide;
Phosphorus oxides such as ammonium phosphate and zinc phosphate, and red phosphorus are exemplified.

The amounts of these flame retardants are EVA100
The amount is preferably 70 parts by weight or less, particularly preferably 1 to 50 parts by weight based on parts by weight.

In the present invention, if necessary, antimony trioxide and / or expanded graphite can be added to EVA as a flame retardant aid. In this case, the compounding amount of the expanded graphite is E
It is preferably 20% by weight or less, especially 1 to 15% by weight of the whole VA film, and the compounding amount of antimony trioxide is 10% by weight or less, particularly 2 to 8% of the whole EVA film.
% By weight.

Such a flame retardant or an EVA film containing a flame retardant and a flame retardant aid can be produced in accordance with a normal EVA film forming method except that a flame retardant or a flame retardant aid is added as an additive. it can.

It is to be noted that EV containing a flame retardant is used as a front side sealing film.
When the A film is used, it is preferable that the EVA film does not include a material that hinders light transmission, such as antimony trioxide and expanded graphite, from the viewpoint of light transmission.

[0038]

The present invention will be described more specifically below with reference to examples and comparative examples.

Example 1 A PET film having a thickness of 500 μm and a zinc steel plate (thickness 2)
A 5 μm steel plate having zinc coatings with a thickness of 5 μm formed on the front and back surfaces of the steel plate was coated with EVA having the following composition to a thickness of 500 μm.
A back side protective member was manufactured by laminating and integrating using an EVA film formed to a thickness of μm.

[EVA blending (parts by weight)] EVA (vinyl acetate content 26% by weight, melt flow rate 4.0): 100 crosslinking agent (1,1-bis (t-butylperoxy) 3,3)
3,5-trimethylcyclohexane): 2.0 Silane coupling agent (γ-methacryloxypropyltrimethoxysilane): 1.0 Crosslinking aid (triallyl isocyanurate): 3.0 Ultraviolet adsorbent (2-hydroxy- 4-octylbenzophenone): 0.3 Flame retardant (aluminum hydroxide): 10 Separately, EVA films obtained by forming the above-mentioned EVA were used as sealing films 3A and 3B, and as shown in FIG.
The solar cell was manufactured by sealing the silicon power generation element 4 between the transparent substrate 1 made of a glass plate and the above-mentioned three-layer film as the back side protection member 2. In addition, sealing was performed at a temperature of 150 ° C. using a vacuum laminator, a deaeration time of 3 minutes, and a press time of
This was carried out by cross-linking the EVA by heating and pressing for minutes.

The solar cell thus manufactured was subjected to a flame retardancy test by heating the edge portion with a gas burner by the following method. The results are shown in Table 1.

<Flame retardancy test> 9.5 from tip of burner
The sample is suspended so that the edge portion of the sample (solar cell) is located at a position separated by mm, a blue flame having a length of 19 mm is emitted from the burner, and the flame is applied to the edge portion of the sample for 3 seconds. Then, the flame is separated from the sample by 150 mm or more, and the time required for the sample to emit flame and burn (first flame burning time) is measured. Immediately after the flame disappears, the flame is again applied to the edge of the sample, and the flame is similarly applied for 3 seconds, then the flame is released, and the time for the sample to emit flame and burn (2)
The second flaming time is measured.

Comparative Example 1 A film was obtained in the same manner as in Example 1 except that a 500 μm-thick PET film was used for the back side protective member and no flame retardant was added as a sealing film. A solar cell was produced in the same manner except that the EVA film was used, and a flame retardancy test was conducted in the same manner. The results are shown in Table 1.

[0044]

[Table 1]

From Table 1, it can be seen that the solar cell of the present invention has its flame retardancy,
It turns out that the nonflammability is remarkably good.

[0046]

As described in detail above, the solar cell of the present invention has remarkably good flame retardancy and non-combustibility, so that it can be used as a roofing material and the construction cost can be reduced. be able to.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a back side protection member according to the present invention.

FIG. 2 is a cross-sectional view illustrating a general solar cell.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transparent substrate 2 Backside protective member 3A, 3B sealing film 4 Silicon power generation element 10, 10A, 10B Backside protective member 11, 15 PET film 12 Zinc steel plate 13, 14 EVA film 16 Coating

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08K 3/32 C08K 3/32 5/02 5/02 5/14 5/14 5/3477 5/3477 5 / 5415 5/5415 C08L 23/08 C08L 23/08 31/04 31/04 // (C08L 23/08 91:08) (C08L 23/08 23:28) F term (reference) 4F071 AA15X AA28X AB18 AB25 AC03 AE07 AF47 AF58 AG05 AH15 BA01 BB06 BC01 BC12 4J002 AE042 BB061 BB242 DE076 DE126 DE146 EB046 EB086 EB096 EB136 EK007 EK057 EU198 EX037 FD132 FD136 FD147 FD158 GQ00 5F051 AA01 BA03 JA02 JA05

Claims (10)

[Claims] 1. A solar cell comprising a solar cell sealed with a sealing film between a front-side transparent protective member and a back-side protective member, wherein the back-side protective member comprises a resin film and ethylene. -A vinyl acetate copolymer resin film and a zinc steel sheet are laminated and integrated, a sealing film interposed between the front-side transparent protective member and the solar cell, and between the rear-side protective member and the solar cell. One or more of the ethylene-vinyl acetate copolymer resin films used for the sealing film to be interposed and the back side protective member are ethylene-vinyl acetate copolymer resin films to which a flame retardant has been added. A solar cell characterized by the above-mentioned. 2. The sealing film for a solar cell according to claim 1, wherein the zinc steel sheet is formed by forming a zinc coating having a thickness of 1 to 10 μm on a surface of a steel sheet having a thickness of 15 to 100 μm. 3. The method according to claim 1, wherein the ethylene-
The thickness of the vinyl acetate copolymer resin film is 5-600μ
m, a sealing film for a solar cell. 4. The solar cell according to claim 1, wherein the resin film is a polyethylene terephthalate film. 5. The solar cell according to claim 1, wherein the flame retardant is an organic flame retardant containing one or more halogen atoms in a molecule. 6. The solar cell according to claim 5, wherein the halogen atom is a chlorine atom or a bromine atom. 7. The solar cell according to claim 1, wherein the flame retardant is an inorganic flame retardant. 8. The solar cell according to claim 7, wherein the inorganic flame retardant is at least one member selected from the group consisting of a hydroxide inorganic salt, a phosphoric oxide, and red phosphorus. 9. The ethylene-vinyl acetate copolymer resin according to claim 1, wherein antimony trioxide and / or expanded graphite are added as a flame retardant aid. Solar cells. 10. The solar cell according to claim 1, wherein the ethylene-vinyl acetate copolymer resin has a crosslinked structure.