JP2012151399A - Sealing film integrating rear side protection member for solar cell and production method therefor, solar cell using it and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sealing film integrating a rear side protection member for solar cell which is mainly composed of an ethylene-polar monomer copolymer and is not likely to cause degradation in adhesion performance, and to provide a solar cell using it.SOLUTION: In a sealing film 10 integrating a rear side protection member for solar cell, a rear side protection member placed on the rear side of an element for solar cell and protecting the element for solar cell and a sealing film for sealing the element for solar cell are integrated. The sealing film 10 integrating a rear side protection member for solar cell has a sealing film sheet 13 containing an ethylene-polar monomer copolymer, and a rear side protection member layer 12 composed of a resin composition formed on the surface thereof by coating. Steam permeability (conforming to JIS-K7129B) is 2.1 g/(mday) or lower. A solar cell using the sealing film integrating a rear side protection member for solar cell is also provided.

Description

  The present invention relates to a back side protection member integrated type for a solar cell in which a back side protection member (also referred to as a back cover material) disposed on the back side of a solar cell element of a solar cell and a solar cell sealing film are integrated. The present invention relates to a sealing film, a manufacturing method thereof, a solar cell using the sealing film, and a manufacturing method thereof.

  In recent years, solar cells that directly convert sunlight into electrical energy have been widely used in terms of effective use of resources and prevention of environmental pollution, and further, performance aspects such as power generation efficiency and weather resistance, and shortening of manufacturing time, etc. Development is in progress from the aspect of production efficiency.

  As shown in FIG. 4, the solar cell generally has a surface side transparent protective member 41 made of a glass substrate or the like, a surface side sealing film 43A, a solar cell cell 44 such as a silicon crystal power generation element, and a back side sealing film. 43B and the back surface side protection member (back cover material) 42 are laminated in this order, deaerated under reduced pressure, and then heated and pressurized to crosslink and cure the surface side sealing film 43A and the back surface side sealing film 43B for adhesion. Manufactured by integrating.

  In such a solar battery, a plurality of solar battery cells 44 are connected and used in order to obtain a high electrical output. Therefore, in order to ensure the insulation of the solar cell 44, the solar cell is sealed using the sealing films 43A and 43B having insulation properties.

  In addition, thin-film solar cells such as thin-film silicon-based, thin-film amorphous silicon-based solar cells, and copper indium selenide (CIS) -based solar cells are also being developed. In this case, for example, transparent substrates such as glass and polyimide substrates A power generation element layer such as a semiconductor layer is formed on the surface of the substrate by a chemical vapor deposition method or the like, and a sealing film and a back cover material are laminated thereon and bonded and integrated.

  Conventionally, as a sealing film used in these solar cells, an ethylene-polar monomer copolymer such as an ethylene vinyl acetate copolymer (hereinafter also referred to as EVA) or an ethylene ethyl acrylate copolymer (EEA) is used. A film is used. In particular, EVA films are preferably used because they are inexpensive and have high transparency. Further, the back cover material is lightweight and has sufficient durability, and high moisture resistance is required to prevent rusting of the conductive wires and electrodes inside the solar cell. Generally, a plastic film such as polyethylene terephthalate (PET) is preferably used for the back cover material.

  By the way, in the manufacture of such a solar cell, the step of laminating each member is a complicated step for positioning and the like and is an important step for shortening the manufacturing time.

  Patent Documents 1 and 2 disclose a sealing film that also serves as a back-side protection member for a solar cell, in which a back cover material such as a moisture-proof film and an adhesive layer such as an EVA film are bonded together. In this case, in the manufacturing site of the solar cell, the stacking process can be reduced and the manufacturing time can be shortened.

JP 2002-26346 A JP 2000-294820 A

  However, when forming a laminated body in which a back cover material and an EVA film are bonded together as in Patent Documents 1 and 2, generally, heating and pressurization is performed for provisional pressure bonding, and therefore, it is used as a sealing film. At this time, there is a risk that the originally designed performance cannot be exhibited, for example, the adhesive force is reduced.

  Therefore, an object of the present invention is a sealing film mainly composed of an ethylene-polar monomer copolymer integrated with a back surface protection member for solar cells, which can shorten the manufacturing time of the solar cell, An object of the present invention is to provide a solar cell back surface protective member-integrated sealing film that does not cause such a problem.

  Moreover, the objective of this invention is providing the manufacturing method of the back surface side protection member integrated sealing film for solar cells.

  Furthermore, the objective of this invention is providing the solar cell using the back surface side protective member integrated sealing film for solar cells.

  Moreover, the objective of this invention is providing the manufacturing method of the solar cell using the back surface side protection member integrated sealing film for solar cells.

The above-mentioned object is arranged on the back side of the solar cell element of the solar cell, and the back surface side protective member for protecting the solar cell element and the sealing film for sealing the solar cell element are integrated. Further, a back surface side protection member-integrated sealing film for solar cells, comprising a sealing film sheet containing an ethylene-polar monomer copolymer, and a resin composition formed on the surface thereof by coating. The back side protection for solar cells, comprising a member layer and having a water vapor transmission rate (based on JIS-K7129B method) of the back side protection member layer of 2.1 g / (m ² · day) or less This is achieved by the member-integrated sealing film.

  Since the back surface protection member integrated sealing film for solar cells of the present invention has a back surface protection member layer formed by coating on the surface of the sealing film sheet, the back surface disclosed in Patent Documents 1 and 2 Like the side protective member sealing film, the sealing film sheet is not subjected to heat and pressure when being bonded to the back side protective member. Thereby, the possibility that the performance originally designed as a sealing film such as adhesive force may be avoided. Furthermore, by setting the back surface side protective member layer to the above-described water vapor transmission rate, a solar cell back surface side protective member-integrated sealing film having sufficient wet heat durability as a solar cell back surface side protective member can be obtained. it can.

The suitable aspect of the back surface side protection member integrated sealing film for solar cells of this invention is as follows.
(1) The said back surface side protection member layer is directly formed in the surface of the said sealing film sheet. Thereby, the layer structure of the back surface side protective member integrated sealing film can be simplified.
(2) The resin composition of the said back surface side protection member layer contains the at least 1 sort (s) of resin material selected from the group which consists of a fluororesin, a polyvinylidene chloride, and polyetherimide. Since these resin materials are excellent in moisture resistance and weather resistance, they are preferable as the resin material for forming the back side protective member layer in the present invention.
(3) The fluororesin is polyvinyl fluoride or a tetrafluoroethylene-ethylene copolymer. Since these fluororesins are particularly excellent in weather resistance and mechanical strength, they are more preferable as a resin material for forming the back side protective member layer in the present invention.

Moreover, the said objective arrange | positions in the back surface side of the element for solar cells of a solar cell, the back surface side protection member for protecting the element for solar cells, and the sealing film for sealing the element for solar cells are integrated. This is a method for producing a solar cell back surface protective member-integrated sealing film, wherein a coating liquid containing a resin composition is applied to the surface of a sealing film sheet containing an ethylene-polar monomer copolymer. Including a step of forming a back-side protective member layer made of a resin composition, and the water-vapor permeability of the back-side protective member layer (based on JIS-K7129B method) is 2.1 g / (m ² · day) or less, which is achieved by a method for producing a solar cell back surface side protective member-integrated sealing film.

  The manufacturing method of the back surface side protection member integrated sealing film for solar cells of this invention is the back surface protection which consists of a resin composition by coating the coating liquid containing a resin composition on the surface of a sealing film sheet. Since the member layer is formed, the sealing film sheet is subjected to heat and pressure when being bonded to the back surface side protective member as in the back surface side protective member combined sealing film disclosed in Patent Documents 1 and 2. There is no manufacturing method. Thereby, in the solar cell back surface side protective member integrated sealing film obtained, it is possible to avoid the possibility that the performance originally designed as a sealing film such as adhesive force is deteriorated. Furthermore, by making the back side protective member layer have the above water vapor transmission rate, a solar cell back side protective member-integrated sealing film having sufficient wet heat durability as a solar cell back side protective member is manufactured. Can do.

The suitable aspect of the manufacturing method of the back surface side protection member integrated sealing film for solar cells of this invention is as follows.
(1) A coating liquid containing the resin composition is directly applied to the surface of the sealing film sheet. Thereby, the back surface side protection member integrated type sealing film which simplified the layer structure of the back surface side protective member integrated type sealing film can be manufactured.
(2) The resin composition contained in the coating solution contains at least one resin material selected from the group consisting of fluororesin, polyvinylidene chloride, and polyetherimide. Since these resin materials are excellent in moisture resistance and weather resistance, they are preferred as the resin material used for forming the back side protective member layer in the present invention.
(3) The fluororesin is polyvinyl fluoride or a tetrafluoroethylene-ethylene copolymer. Since these fluororesins are particularly excellent in weather resistance and mechanical strength, they are more preferable as a resin material used for forming the back side protective member layer in the present invention.

  Furthermore, the above object is achieved by a solar cell characterized in that the solar cell back surface side protective member-integrated sealing film of the present invention is used on the back surface side of the solar cell element.

  In the solar cell of the present invention, since the back surface protection member-integrated sealing film for solar cell of the present invention is used on the back surface side of the solar cell element, the production cost is reduced by shortening the manufacturing time, In addition, the solar cell has sufficient wet heat durability.

  Moreover, the said objective adhere | attaches by heating and pressurizing the laminated body which contains the solar cell element and the back surface side protection member integrated sealing film for solar cells of this invention laminated | stacked on the back surface side in a layer structure. This is achieved by a method for manufacturing a solar cell including an integrating step.

  Since the manufacturing method of the solar cell of this invention can simplify a lamination process by laminating | stacking the back surface protection member integrated sealing film for solar cells of this invention on the back surface side of the element for solar cells, a solar cell It is a manufacturing method which can shorten manufacturing time. In addition, in the manufacturing method of the solar cell of this invention, the layer structure of a laminated body should just contain said structure. For example, the surface side transparent protective member, the surface side sealing film, the solar cell element (solar cell), and the solar cell back side protective member integrated sealing film of the present invention may be laminated in this order. The solar cell element (thin film solar cell element) formed on the surface of the transparent substrate and the solar cell back surface protective member integrated sealing film of the present invention may be laminated.

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

  According to the present invention, the back side protective material-integrated seal for solar cells excellent in sealing performance and wet heat durability is avoided, in which the possibility that the performance originally designed as a sealing film such as adhesive force is reduced is avoided. Since the stop film is obtained, in the production of the solar cell, the lamination process can be simplified and the production time can be shortened without impairing the wet heat durability of the solar cell. Therefore, according to the present invention, it is possible to provide a solar cell with reduced production cost and sufficient wet heat durability.

It is a schematic sectional drawing which shows a typical example of the back surface side protection member integrated sealing film for solar cells of this invention. It is a schematic sectional drawing which shows a typical example of the solar cell of this invention. It is a schematic sectional drawing which shows another example of the solar cell of this invention. It is a schematic sectional drawing of a common solar cell.

  Below, the back surface side protection member integrated sealing film for solar cells of this invention is demonstrated, referring drawings. FIG. 1 is a schematic cross-sectional view showing a typical example of the back surface side protective member integrated sealing film of the present invention. As shown in FIG. 1, the back surface side protective member integrated sealing film 10 of the present invention includes a sealing film sheet 13 containing an ethylene-polar monomer copolymer, and a resin composition formed on the entire surface thereof by coating. It is comprised by the back surface side protection member layer 12 which consists of a thing. In general, a layer composed of a resin composition by coating (also referred to as a coating film) is formed by applying a coating liquid containing a resin composition containing a resin material and a solvent with a gravure coater and drying the solvent. By evaporating. Therefore, the back-side protective member layer 12 that is a coating film is used when the back-side protective member film is bonded to the sealing film like the back-side protective member combined sealing film disclosed in Patent Document 1 or 2. Therefore, it is not subjected to heating and pressurization in the temporary press bonding necessary for the above. With such an ethylene-polar monomer copolymer film having no heating / pressing history, it is possible to avoid the possibility that the performance originally designed as a sealing film such as adhesive force is deteriorated.

And the water-vapor-permeation rate (based on JIS-K7129B method, same hereafter) of the back surface side protection member layer 12 is 2.1 g / (m < ² > * day) or less. Here, the water vapor transmission rate is a water vapor transmission rate measuring apparatus (for example, manufactured by MOCON) using the infrared sensor method to measure the mass of water vapor that passes through a 1 m ² film in one day under the conditions of a temperature of 40 ° C. and a humidity of 90% RH. It is measured by. As shown in Examples described later, the above-described water vapor transmission rate can provide the back-side protection member layer 12 having sufficient wet heat durability as the back-side protection member. Although the water vapor transmission rate of the back surface side protection member layer 12 changes with resin materials and layer thickness to be used, it is 0.1-2.1 g / (m < ² > * day) normally.

  In addition, although another layer may exist between the back surface side protection member layer 12 and the sealing film sheet 13, in order to simplify a layer structure, the back surface side protection member layer 12 is the sealing film sheet 13. It is preferable to be formed directly on the surface.

[Back side protection member layer]
In the present invention, the layer thickness D of the back-side protection member layer 12 may be any layer thickness as long as the back-side protection member layer 12 can have the above water vapor transmission rate, and can be appropriately adjusted depending on the resin material. The layer thickness D is generally 1 mm or less, and depending on the resin material, if the layer thickness D is too thick, disturbance such as undulation may occur on the surface of the coating film. Therefore, the layer thickness D is preferably 850 μm or less, and 600 μm or less. Further preferred.

  Any resin material may be used in the resin composition of the coating liquid for forming the coating film of the back surface side protective member layer 12. In order not to make the layer thickness D too thick, a resin material having high moisture resistance is preferable. For example, polyvinyl fluoride (PVF), tetrafluoroethylene-ethylene copolymer (ETFE), polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkoxyethylene copolymer (PFA), tetrafluoroethylene-hexafluoro Fluorine resins such as propylene copolymer (FEP), polychlorotrifluoroethylene (PCTEF), and polyvinylidene fluoride (PVDF), polyesters such as polyvinylidene chloride (PVDC), polyetherimide (PEI), and polyethylene terephthalate (PET) Various resin materials such as polycarbonate (PC) and polymethyl methacrylate (PMMA) can be used alone or in combination of two or more. Among these resin materials, fluorine resin, polyvinylidene chloride, and polyetherimide, which are excellent in moisture resistance and weather resistance, are preferable. Further, as the fluororesin, polyvinyl fluoride (PVF) or tetrafluoroethylene-ethylene copolymer (ETFE) having particularly excellent weather resistance and mechanical strength is preferable.

  The solvent contained in the coating solution may be any solvent as long as the resin material used can be dissolved to form a uniform solution. For example, organic solvents such as toluene, n-hexane, methyl ethyl ketone (MEK), ethylene glycol monomethyl ether acetate (MCA) can be used.

[Sealing film sheet]
In this invention, the sealing film sheet 13 should just contain the ethylene-polar monomer copolymer as a main component. Although the thickness in particular of the sealing film sheet 13 is not restrict | limited, Usually, it is the range of 50 micrometers-2 mm.

[Ethylene-polar monomer copolymer]
Examples of the polar monomer of the ethylene-polar monomer copolymer of the sealing film sheet 13 include unsaturated carboxylic acids, salts thereof, esters thereof, amides, vinyl esters, and carbon monoxide. More specifically, unsaturated carboxylic acids such as acrylic acid, methacrylic acid, fumaric acid, itaconic acid, monomethyl maleate, monoethyl maleate, maleic anhydride, itaconic anhydride, lithium of these unsaturated carboxylic acids, sodium, Salts of monovalent metals such as potassium, salts of polyvalent metals such as magnesium, calcium and zinc, methyl acrylate, ethyl acrylate, isopropyl acrylate, isobutyl acrylate, n-butyl acrylate, isooctyl acrylate, methacrylic acid Examples include unsaturated carboxylic acid esters such as methyl, ethyl methacrylate, isobutyl methacrylate, and dimethyl maleate, vinyl esters such as vinyl acetate and vinyl propionate, carbon monoxide, sulfur dioxide, etc. be able to.

  More specifically, as the ethylene-polar monomer copolymer, ethylene-acrylic acid copolymer, ethylene-unsaturated carboxylic acid copolymer such as ethylene-methacrylic acid copolymer, the ethylene-unsaturated carboxylic acid Ionomer in which some or all of carboxyl groups of copolymer are neutralized with the above metal, ethylene-methyl acrylate copolymer, ethylene-ethyl acrylate copolymer, ethylene-methyl methacrylate copolymer, ethylene- Isobutyl acrylate copolymer, ethylene-unsaturated carboxylic acid ester copolymer such as ethylene-n-butyl acrylate copolymer, ethylene-isobutyl acrylate-methacrylic acid copolymer, ethylene-n-butyl acrylate -Ethylene-unsaturated carboxylic acid ester-unsaturated carboxylic acid such as methacrylic acid copolymer Some or all of the copolymer and its carboxyl group ionomer neutralized with the metal, ethylene - can be exemplified vinyl ester copolymer as a typical example - ethylene such as vinyl acetate copolymer.

  As the ethylene-polar monomer copolymer of the sealing film sheet 13, an ethylene-vinyl acetate copolymer (also referred to as EVA) is particularly preferable. Thereby, it can be set as the sealing film sheet 13 which is cheaper and excellent in transparency and a softness | flexibility.

  The content of vinyl acetate in the ethylene-vinyl acetate copolymer is preferably 20 to 35% by mass, more preferably 22 to 30% by mass, and particularly preferably 24 to 28% by mass with respect to the ethylene-vinyl acetate copolymer. . If the vinyl acetate content is less than 20% by mass, the transparency and flexibility of the sealing film obtained when crosslinked and cured at a high temperature may not be sufficient. If it exceeds 35% by mass, the carboxylic acid, Alcohol, amine, etc. generate | occur | produce and there exists a possibility that it may become easy to produce foam at the interface of the sealing film sheet 13 and the back surface side protection member layer 12. FIG.

  In the present invention, in addition to the ethylene-polar monomer copolymer, a polyvinyl acetal resin (for example, polyvinyl formal, polyvinyl butyral (PVB resin), modified PVB) or a vinyl chloride resin may be used as a secondary agent. . In that case, PVB is particularly preferable.

[Crosslinking agent]
In this invention, the sealing film sheet 13 contains the crosslinking agent normally, in order to seal the element for solar cells by heating and pressurization at the time of manufacture of a solar cell.

  The cross-linking agent is capable of forming a cross-linked structure of an ethylene-polar monomer copolymer. In the present invention, it is preferable to use an organic peroxide as the crosslinking agent because a sealing film having improved temperature dependency of adhesive strength, transparency, moisture resistance, and penetration resistance is obtained.

  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, those having a decomposition temperature of 70 hours or more with a half-life of 10 hours are preferred.

  Examples of the organic peroxide include, from the viewpoint of resin processing temperature and storage stability, for example, benzoyl peroxide curing agent, tert-hexyl peroxypivalate, tert-butyl peroxypivalate, 3, 5, 5- Trimethylhexanoyl peroxide, di-n-octanoyl peroxide, lauroyl peroxide, stearoyl peroxide, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, succinic acid peroxide, 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane, 2,5-dimethyl-2,5-di (2-ethylhexanoylperoxy) hexane, 1-cyclohexyl-1-methylethyl Peroxy-2-ethylhexanoate, tert-hexyl par Xyl-2-ethylhexanoate, 4-methylbenzoyl peroxide, tert-butylperoxy-2-ethylhexanoate, m-toluoyl + benzoyl peroxide, benzoyl peroxide, 1,1-bis (tert-butyl Peroxy) -2-methylcyclohexanate, 1,1-bis (tert-hexylperoxy) -3,3,5-trimethylcyclohexanate, 1,1-bis (tert-hexylperoxy) cyclohexanate 1,1-bis (tert-butylperoxy) -3,3,5-trimethylcyclohexane, 1,1-bis (tert-butylperoxy) cyclohexane, 2,2-bis (4,4-di-tert) -Butylperoxycyclohexyl) propane, 1,1-bis (tert-butyl) -Oxy) cyclododecane, tert-hexylperoxyisopropyl monocarbonate, tert-butylperoxymaleic acid, tert-butylperoxy-3,3,5-trimethylhexane, tert-butylperoxylaurate, 2,5- Dimethyl-2,5-di (methylbenzoylperoxy) hexane, tert-butylperoxyisopropyl monocarbonate, tert-butylperoxy-2-ethylhexyl monocarbonate, tert-hexylperoxybenzoate, 2,5-di-methyl -2,5-di (benzoylperoxy) hexane, and the like.

  As the benzoyl peroxide-based curing agent, any can be used as long as it decomposes at a temperature of 70 ° C. or higher to generate radicals, and those having a decomposition temperature of 50 hours or higher with a half-life of 10 hours are preferable, It can be appropriately selected in consideration of preparation conditions, film formation temperature, curing (bonding) temperature, heat resistance of the adherend, and storage stability. Usable benzoyl peroxide curing agents include, for example, benzoyl peroxide, 2,5-dimethylhexyl-2,5-bisperoxybenzoate, p-chlorobenzoyl peroxide, m-toluoyl peroxide, 2, Examples include 4-dichlorobenzoyl peroxide and t-butyl peroxybenzoate. The benzoyl peroxide curing agent may be used alone or in combination of two or more.

  As the organic peroxide, 2,5-dimethyl-2,5di (tert-butylperoxy) hexane and 1,1-bis (tert-hexylperoxy) -3,3,5-trimethylcyclohexane are particularly preferable. . Thereby, the sealing film for solar cells which has the outstanding insulating property is obtained.

  The content of the organic peroxide is preferably 0.1 to 2 parts by mass, more preferably 0.2 to 1.5 parts by mass with respect to 100 parts by mass of the ethylene-polar monomer copolymer. preferable. If the content of the organic peroxide is small, the insulating properties of the resulting sealing film may be lowered, and if it is increased, the compatibility with the copolymer may be deteriorated.

[Crosslinking aid]
In the present invention, the sealing film sheet 13 may further contain a crosslinking aid as necessary. The cross-linking aid can improve the gel fraction of the ethylene-polar monomer copolymer and improve the adhesion and durability of the sealing film.

  The content of the crosslinking aid is generally 10 parts by mass or less, preferably 0.1 to 5 parts by mass, more preferably 0.1 to 2.5 parts by mass with respect to 100 parts by mass of the ethylene-polar monomer copolymer. Used in the department. Thereby, the sealing film excellent in adhesiveness is obtained.

  Examples of the crosslinking aid (compound having a radical polymerizable group as a functional group) include trifunctional crosslinking aids such as triallyl cyanurate and triallyl isocyanurate, and (meth) acrylic esters (eg, NK ester) ) Monofunctional or bifunctional crosslinking aids. Of these, triallyl cyanurate and triallyl isocyanurate are preferable, and triallyl isocyanurate is particularly preferable.

[Adhesion improver]
In the present invention, the sealing film sheet 13 may further contain an adhesion improver in order to further improve the adhesion performance. As the adhesion improver, a silane coupling agent can be used. Thereby, the sealing film sheet 13 can have more sufficient sealing performance. 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. Of these, γ-methacryloxypropyltrimethoxysilane is particularly preferred.
The content of the silane coupling agent is preferably 0.1 to 0.7 parts by mass, particularly 0.15 to 0.65 parts by mass with respect to 100 parts by mass of the ethylene-polar monomer copolymer.

[Others]
In the present invention, the sealing film sheet 13 is necessary for improving or adjusting various physical properties of the sealing film (optical properties such as mechanical strength and transparency, heat resistance, light resistance, crosslinking speed, etc.). Accordingly, various additives such as a plasticizer, an acryloxy group-containing compound, a methacryloxy group-containing compound, and / or an epoxy group-containing compound may further be included.

  Although it does not specifically limit as a plasticizer, Generally the ester of a polybasic acid and the ester of a polyhydric alcohol are 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 the ethylene-polar monomer copolymer.

  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 epoxy-containing compounds 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, and phenol. (Ethyleneoxy) ₅ glycidyl ether, pt-butylphenyl glycidyl ether, adipic acid diglycidyl ester, phthalic acid diglycidyl ester, glycidyl methacrylate, butyl glycidyl ether can be mentioned.

  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 weight, particularly 1.0, respectively, with respect to 100 parts by weight of the ethylene-polar monomer copolymer. It is preferable that -4.0 mass part is contained.

  Furthermore, in this invention, sealing film sheet 13Bb may contain the ultraviolet absorber, the light stabilizer, and anti-aging agent. By including the ultraviolet absorber, it is possible to suppress deterioration of the ethylene-polar monomer copolymer due to the influence of irradiated light and the like, and yellowing of the solar cell sealing film. The ultraviolet absorber is not particularly limited, but 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-n-dodecyloxybenzophenone, 2,4-dihydroxybenzophenone, 2,2′-dihydroxy-4-methoxy. Preferred examples include benzophenone-based ultraviolet absorbers such as benzophenone and 2-hydroxy-4-n-octoxybenzophenone. In addition, it is preferable that the compounding quantity of the said benzophenone series ultraviolet absorber is 0.01-5 mass parts with respect to 100 mass parts of ethylene-polar monomer copolymers.

  Moreover, it can suppress that an ethylene-polar monomer copolymer deteriorates and the solar cell sealing film yellows by influence of the irradiated light etc. also by including a light stabilizer. 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), Tinuvin 744, Tinuvin 770, Tinuvin 765, Tinuvin 144, Tinuvin 622LD, CHIMASSORB 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 the compounding quantity is 0.01-5 mass parts with respect to 100 mass parts of ethylene-polar monomer copolymers. It is preferable that

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

[Production Method of Back Side Protective Material Integrated Sealing Film]
What is necessary is just to perform according to a well-known method in order to manufacture the back surface side protection member integrated sealing film for solar cells of this invention mentioned above. For example, first, the material of the composition mainly composed of ethylene-polar monomer of the sealing film sheet 13 is mixed by a known method using a super mixer (high speed fluid mixer), a roll mill, etc. Molding or calendering (calendering) or the like to obtain a sheet-like material, or the composition is dissolved in a solvent, and this solution is coated on a suitable support with a coater such as a die coater, A sheet is obtained by drying to form a coating film. The temperature at which the sealing film sheet 13 is formed is preferably a temperature at which the crosslinking agent does not react or hardly reacts. For example, it is preferable to set it as 40-90 degreeC, especially 40-80 degreeC.

Subsequently, in order to form the coating film of the back surface side protection member layer 12, the resin material mentioned above is melt | dissolved in a solvent by a well-known method, and the coating liquid used as the uniform solution is prepared. This is coated on the surface of the sealing film sheet 13 using a coater such as a gravure coater, a die coater, a reverse roll coater, a roll knife coater (also referred to as a comma coater). At this time, in consideration of the moisture-proof performance of the resin material to be used, the water vapor transmission rate (based on JIS-K7129B method) of the coating film of the back side protective member layer 12 to be formed is 2.1 g / (m ² · day). The coating thickness is adjusted so that a coating film having a layer thickness D as shown below is formed. After coating, the solvent is evaporated by drying by a known method to form a coating film. At this time, the sealing film sheet 13 is preferably heated at a low temperature so that the performance originally designed as a sealing film such as adhesive strength is not deteriorated by heating the sealing film sheet 13 during drying. . Accordingly, the drying temperature is preferably 20 to 80 ° C, and more preferably 20 to 60 ° C.

  In addition, although another coating film may be formed between the back surface side protection member layer 12 and the sealing film sheet 13, the back surface side protection member layer 12 is sealed to simplify the layer configuration. It is preferable to form directly on the surface of the film-stopping sheet 13.

  Although the thickness of the back surface side protective member integrated sealing film 10 varies depending on the resin material used for the back surface side protective member layer 12, it is usually in the range of 100 μm to 3 mm.

[Solar cell]
As the structure of the solar cell of the present invention, at least the back surface protection member-integrated sealing film for solar cell of the present invention is used as a solar cell element (single crystal or polycrystalline silicon crystal solar cell or thin film solar cell). If it uses for the back surface side of a battery power generation element), it will not be restrict | limited in particular. For example, the structure which laminated | stacked the surface side transparent protective member, the surface side sealing film, the element for solar cells (cell for solar cells), and the back surface side protective member integrated sealing film of this invention in this order, and was integrated by bridge | crosslinking. Or a transparent substrate, a solar cell element (thin film solar cell element) formed on the surface of the transparent substrate, and a back surface protection member integrated sealing film for solar cell of the present invention. Examples include the structure.

  In these solar cells, in order to sufficiently seal the solar cell elements, for example, as shown in FIG. 2, the surface side transparent protective member 21, the surface side sealing film 23, the solar cell 24, and the book What is necessary is just to laminate | stack the back surface side protective member integrated sealing film 10 of invention, and to bridge-harden the surface side sealing film 23 and the sealing film sheet | seat 13 in accordance with conventional methods, such as heating and pressurization. As the surface side sealing film 23, a well-known solar cell sealing film can be used. Usually, a sealing film containing ethylene-polar monomer copolymer as a main component is used.

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. The surface-side transparent protective member is crosslinked by crosslinking the ethylene-polar monomer copolymer contained in the sealing film sheet 13 of the front-side sealing film 23 and the back-side protective member-integrated sealing film 10 during this heating and pressurization. 21, the front surface side sealing film 23, the solar battery cell 24, and the back surface side protective member integrated sealing film 10 can be integrated to seal the solar battery cell 24.

  As the surface side transparent protective member 11, it is usually good to be 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.

  Moreover, as a thin film solar cell, a thin film silicon type, a thin film amorphous silicon type solar cell, a copper indium selenide (CIS) type solar cell, etc. are mentioned. In that case, as shown in FIG. 3, a thin-film solar cell element layer 34 is formed on the surface of the front-side transparent protective member 31 by chemical vapor deposition or the like, and the back-side protective member-integrated seal of the present invention is formed on the surface. The thin film solar cell element layer 34 can be sealed by laminating the stop film 10 and crosslinking and curing the sealing film sheet 13 in accordance with a conventional method such as heating and pressurization in the same manner as described above.

  Examples of the surface-side transparent protective member 31 of the thin-film solar cell include a glass substrate, a polyimide substrate, and a fluororesin-based transparent substrate. Further, in the thin film solar cell, the thin film solar cell element may not be directly formed on the front surface side transparent protective member, the front surface side transparent protective member, the front surface side sealing film, the thin film solar cell element, and the back surface of the present invention. The side protective member-integrated sealing film may be laminated in this order, and may be bonded and integrated.

  Since the solar cell of the present invention uses the solar cell back surface protective member-integrated sealing film of the present invention, the manufacturing time is simplified by simplifying the stacking process as compared with the case of using the conventional sealing film. The possibility that the performance originally designed as the sealing film such as the adhesive force is shortened is also reduced. Therefore, it is a solar cell with reduced production cost and sufficient wet heat durability.

  In addition, the solar cell (including the thin film solar cell) of the present invention is characterized by using the back surface side protective member integrated sealing film as described above. Therefore, members other than the back-side protection member-integrated sealing film such as the front-side transparent protective member, the front-side sealing film, and the solar cell element have the same configuration as a conventionally known solar cell. Well, not particularly limited.

  Hereinafter, the present invention will be described with reference to examples.

1. Production of sealing film integrated with back surface side protective member (1) Production of sealing film sheet The material of the sealing sheet composition having the following composition was supplied to a roll mill and kneaded at 70 ° C. for solar cell sealing. A film composition was prepared. The composition for solar cell sealing film was calendered at 70 ° C., allowed to cool, and then a sealing film sheet (thickness 0.6 mm) was produced.
(Combination)
EVA (vinyl acetate content 26% by mass in EVA): 100 parts by mass,
Cross-linking agent (2,5-dimethyl-2,5-bis (tert-butylperoxy) hexane): 1.0 part by mass,
Crosslinking aid (triallyl isocyanurate): 2.0 parts by mass Adhesion improver (γ-methacryloxypropyltrimethoxysilane): 0.15 parts by mass

(2) Formation of back surface side protective member layer The materials of the resin composition of the following mixing | blending AD were mixed well, respectively, and the coating liquid for back surface side protective member layers was prepared. This was coated on the surface of the sealing film sheet by adjusting the coating thickness so that the coating film formed after drying using a gravure coater had the thickness shown in Table 1. Then, it dried at 25 degreeC for 6 minute (s), and formed the back side protective member layer which consists of a coating film. Thereby, the back surface side protection member integrated sealing film of Examples 1-10 and Comparative Examples 1-2 was produced.
(Formulation A)
Resin material (polyvinyl fluoride (PVF)): 100 parts by mass Solvent (Methyl ethyl ketone (MEK) / ethylene glycol monomethyl ether acetate (MCA) mixture): 10 parts by mass (Formulation B)
Resin material (tetrafluoroethylene-ethylene copolymer (ETFE)): 100 parts by mass Solvent (Methyl ethyl ketone (MEK) / ethylene glycol monomethyl ether acetate (MCA) mixture): 10 parts by mass (formulation C)
Resin material (polyvinylidene chloride (PVDC)): 100 parts by mass Solvent (Methyl ethyl ketone (MEK) / ethylene glycol monomethyl ether acetate (MCA) mixture): 10 parts by mass (Formulation D)
Resin material (polyetherimide (PEI)): 100 parts by mass Solvent (Methyl ethyl ketone (MEK) / ethylene glycol monomethyl ether acetate (MCA) mixture): 10 parts by mass

2. Production of solar cell sample Using the sealing film sheet produced in (1) as a surface-side sealing film, a surface-side transparent protective member (FL glass plate (thickness: 3 mm)), surface-side sealing film, solar cell, Example 1 10 and Comparative Examples 1-2 are laminated in this order on the back side protective member-integrated sealing film, temporarily bonded at 90 ° C. with a vacuum laminator, heated in an oven at 155 ° C. for 30 minutes, and gelled. Crosslinking was performed to a fraction of 90% or more (see FIG. 2).

  In Comparative Example 3, the above 1. Using the sealing film sheet produced in (1) as the front side sealing film and the back side sealing film, the front side transparent protective member (FL glass (thickness 3 mm)), the front side sealing film, and for solar cells A cell, a back surface side sealing film, and a back surface side protection member (PVF / PET / PVF laminated film (thickness 350 μm)) are laminated in this order, and temporarily bonded at 90 ° C. with a vacuum laminator, and then 155 ° C. in an oven. , And heated for 30 minutes to crosslink to a gelation fraction of 90% or more (see FIG. 4).

3. Evaluation Method (1) Water Vapor Transmission Rate The water vapor transmission rate of the back surface side protective member layer is based on JIS-K7129B method, and the water vapor that 1 m ² membrane permeates in 1 day under the conditions of temperature 40 ° C. and humidity 90% RH. The mass was measured.
(2) Coating property When producing the back surface side protective member integrated sealing film, the surface state of the coating film of the back surface side protective member layer (the presence or absence of surface disturbance such as waviness) was visually evaluated. The case where the surface state was smooth and had no problem was rated as ◯, and a slight swell was observed.
(3) Wet heat durability Each solar cell sample was allowed to stand for 2000 hours at a temperature of 85 ° C. and a humidity of 85% RH, and then was checked for peeling of the back surface side protective member layer. The case where there was no peeling was marked with ◯, and the case where peeling was observed was marked with ×.
(4) Lamination Handling Time Time from taking out the back surface side protection member integrated sealing film (Comparative Example 3 is sealing film, back surface side protection member) to cutting and stacking on the arranged solar cell ( Seconds).

4). Evaluation results Table 1 shows the evaluation results.

As shown in Table 1, the sun using the back-side protective member-integrated sealing film of Examples 1 to 10 having a back-side protective member layer having a water vapor transmission rate of 2.1 g / (m ² · day) or less It was confirmed that the battery sample showed sufficient wet heat durability as in Comparative Example 3, which is a solar battery having an existing configuration. And it was recognized by using these back surface side protection member integrated sealing films that lamination | stacking handling time can be shortened from the solar cell of the existing structure.

  In addition, this invention is not limited to the structure and Example of said embodiment, A various deformation | transformation is possible within the range of the summary of invention.

  According to the present invention, it is possible to provide a solar cell with reduced production cost and sufficient wet heat durability.

DESCRIPTION OF SYMBOLS 10 Back surface side protection member integrated sealing film 12 Back surface side protection member layer 13 Sealing film sheet 21, 31, 41 Surface side transparent protection member 23, 43A Surface side sealing film 24, 44 Cell for solar cells 34 Thin film solar cell element
42 Back side protection member 43B Back side sealing film

Claims (10)

A solar cell, which is disposed on the back side of the solar cell element of the solar cell, and is integrated with a back side protection member for protecting the solar cell element and a sealing film for sealing the solar cell element Back side protective member integrated sealing film for
A sealing film sheet containing an ethylene-polar monomer copolymer, and a back surface protective member layer made of a resin composition formed by coating on the surface thereof; and a water vapor transmission rate of the back surface protective member layer ( JIS-K7129B method) is 2.1 g / (m ² · day) or less.   The back surface protection member integrated sealing film for solar cells according to claim 1, wherein the back surface protection member layer is directly formed on the surface of the sealing film sheet.   The back surface for solar cells of Claim 1 or 2 in which the resin composition of the said back surface side protection member layer contains the at least 1 sort (s) of resin material selected from the group which consists of a fluororesin, a polyvinylidene chloride, and a polyetherimide. Side protection member integrated sealing film.   The back surface protection member-integrated sealing film for solar cells according to claim 3, wherein the fluororesin is polyvinyl fluoride or a tetrafluoroethylene-ethylene copolymer. A solar cell, which is disposed on the back side of the solar cell element of the solar cell, and is integrated with a back side protection member for protecting the solar cell element and a sealing film for sealing the solar cell element A manufacturing method of a back side protective member integrated sealing film for use,
Including a step of forming a back side protective member layer made of the resin composition by coating a coating liquid containing the resin composition on the surface of the sealing film sheet containing the ethylene-polar monomer copolymer, and The back surface side protective member-integrated sealing film for solar cells, wherein the back surface side protective member layer has a water vapor transmission rate (based on JIS-K7129B method) of 2.1 g / (m ² · day) or less Production method.   The manufacturing method of the solar cell back surface protection member integrated sealing film of Claim 5 which coats the coating liquid containing the said resin composition directly on the surface of the said sealing film sheet.   The back surface for solar cells according to claim 5 or 6, wherein the resin composition contained in the coating liquid contains at least one resin material selected from the group consisting of a fluororesin, polyvinylidene chloride, and polyetherimide. Method for manufacturing side protection member-integrated sealing film.   The method for producing a solar cell back surface protective member-integrated sealing film according to claim 7, wherein the fluororesin is polyvinyl fluoride or a tetrafluoroethylene-ethylene copolymer.   The solar cell which used the back surface side protection member integrated sealing film for solar cells of any one of Claims 1-4 for the back surface side of the element for solar cells.   A solar cell element and a laminate including the solar cell back surface protective member-integrated sealing film according to any one of claims 1 to 4 laminated on the back surface side thereof are heated and heated. The manufacturing method of the solar cell including the process of carrying out adhesion integration by pressing.

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