JP5591564B2 - Solar cell sealing film and solar cell using the same - Google Patents

Description

  The present invention relates to a solar cell encapsulating film comprising an ethylene-polar monomer copolymer as a main component, and particularly a solar in which a decrease in insulating property under a high temperature environment is suppressed, adhesion is improved, and yellowing does not occur. The present invention relates to a battery sealing film.

  In recent years, solar cells that directly convert sunlight into electrical energy have been widely used from the standpoints of effective use of resources and prevention of environmental pollution, and development has been promoted from the viewpoint of productivity and durability.

  As shown in FIG. 1, the solar cell generally has a surface-side transparent protective member 11 made of a glass substrate or the like, a surface-side sealing film 13A, a solar battery cell 14 such as a silicon power generation element, a back-side sealing film 13B, And the back side protection member (back cover) 12 are laminated in this order, degassed under reduced pressure, and heated and pressurized to crosslink and cure the front side sealing film 13A and the back side sealing film 13B, thereby bonding and integrating. It is manufactured by doing. In a conventional solar battery, a plurality of solar battery cells 14 are connected and used in order to obtain a high electric output. Therefore, in order to ensure insulation between the solar battery cells 14, the solar battery cells are sealed using the sealing films 13A and 13B having insulation properties.

  A transparent substrate such as a glass substrate is used for a surface-side transparent protective member used in a conventional solar cell in order to make sunlight enter the battery as efficiently as possible and concentrate it on the solar cell. On the other hand, in order to prevent moisture intrusion into the inside of the battery, the back side protective member uses a plastic film such as polyethylene terephthalate (PET) or a film on which the vapor deposition film made of silver is formed. It has been.

  In addition, the sealing film used on the front surface side and the back surface side is required to prevent foreign matter and moisture from entering the battery and to ensure insulation between the solar cells and the electrodes inside the battery. -A film made of an ethylene-polar monomer copolymer such as vinyl acetate copolymer (EVA) or ethylene-ethyl acrylate copolymer (EEA) is used.

JP 2008-205448 A

  In solar cells, it is necessary to reliably extract electricity generated from incident sunlight to the outside of the cell. Therefore, it is necessary for the sealing film for solar cells to ensure insulation between the solar cells and electrodes inside the battery and prevent the occurrence of leakage current.

  However, solar cells are used in harsh environments exposed to high temperatures, high humidity, and wind and rain, such as outdoors, for a long period of time, which is said to be several decades or longer. In particular, when used in a high-temperature environment such as a hot summer sun, a conventional solar cell may have poor insulation, resulting in reduced power generation performance. Therefore, a sealing film made of an ethylene-polar monomer copolymer is required to have excellent insulating properties even under a high temperature environment.

  Also, at the interface between the front surface side sealing film or the back surface side sealing film and the front surface side transparent protective member or the back surface side protective member at the time of heating and pressurization when manufacturing the solar cell or when the solar cell is installed outdoors In some cases, foaming or peeling may occur. When foaming or peeling occurs, moisture enters the interface between the sealing film and the protective member, not only lowering the insulation, but also impairing the vapor shielding and gas shielding properties of the protective member, resulting in the power generation performance of the solar cell. Cause a decline. Therefore, the sealing film is also required to have high adhesiveness. In order to improve adhesiveness, a silane coupling agent has been conventionally used. However, a silane coupling agent having an amino group is not usually used because yellowing occurs due to ultraviolet rays. When the sealing film turns yellow, the design property is lowered and the power generation performance of the solar cell is lowered.

  Accordingly, an object of the present invention is to provide a solar cell encapsulant comprising an ethylene-polar monomer copolymer as a main component, in which a decrease in electrical insulation under a high temperature environment is suppressed, yellowing does not occur, and adhesion is improved. To provide a stop film. Moreover, it is providing the solar cell using this sealing film.

  For the sealing film mainly composed of an ethylene-polar monomer copolymer, in order to suppress a decrease in insulation under a high temperature environment, further prevent yellowing and improve adhesiveness, the present inventor As a result of examination, a silane coupling agent (A) having an aminoalkyl group at the terminal (hereinafter also referred to as “silane coupling agent (A)”) and a silane coupling agent (B) having no amino group (hereinafter referred to as “silane coupling agent (A)”). , Also referred to as a silane coupling agent (B)) was found to be effective to contain both in the sealing film. However, if the blending amount of the silane coupling agent (A) is too large, bleeding occurs, causing problems that the resistance value is lower than expected or the sealing film is yellowed. The effect of suppressing the decrease was not sufficiently obtained. Then, as a result of further study on the amount of the silane coupling agent (A), the present inventor has reached the present invention.

That is, the object is a sealing film for a solar cell containing an ethylene-polar monomer copolymer and a silane coupling agent, and the silane coupling agent is a silane coupling agent having an aminoalkyl group at the terminal (A ) And a silane coupling agent (B) having no amino group, and the content of the silane coupling agent (A) is 0.12 to 100 parts by mass of the ethylene-polar monomer copolymer. 0.5 parts by mass der is, the content of the silane coupling agent (B), the ethylene - against polar monomer copolymer 100 parts by weight of 0.12 to 1.9 parts by mass der Rukoto It is achieved by a solar cell sealing film characterized by the following.

  When the silane coupling agent (A) having an aminoalkyl group at the terminal is blended in the sealing film, it is possible to suppress a decrease in insulation under a high temperature environment, and by blending the above two types of silane coupling agents. Since the amount of the silane coupling agent (A) as an adhesion improver can be reduced as compared with the case where it is used alone, the adhesion can be prevented while preventing yellowing of the sealing film. Can be improved.

Preferred embodiments of the solar cell sealing film according to the present invention are as follows.
(1) The silane coupling agent (A) is represented by the following formula (1)

(Wherein R ¹ , R ² , and R ³ are alkyl groups, R ⁴ is a hydrogen atom or an aminoalkyl group, and n is an integer of 1 to 6). .
(2) Silane coupling agent (A) having an aminoalkyl group at the terminal is N-2 (aminoethyl) -3-aminopropyltrimethoxysilane, N-2 (aminoethyl) -3-aminopropylmethyldimethoxysilane , A silane coupling agent selected from the group consisting of 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane.
(3) The silane coupling agent (B) having no amino group is 3-methacryloxypropyltrimethoxysilane or 3-methacryloxypropylmethyldimethoxysilane.
( 4 ) The ethylene-polar monomer copolymer is an ethylene-vinyl acetate copolymer.

  The above object is also achieved by a solar cell using the solar cell sealing film of the present invention.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the sealing film for solar cells which is excellent in insulating property also in a high temperature environment, improves adhesiveness, and does not produce yellowing. Therefore, by using the solar cell sealing film of the present invention for a solar cell, it is excellent in electrical insulation even under extremely severe high temperature environment such as under hot weather, and does not yellow even after long-term use. By preventing peeling of the sealing film due to a decrease in force, a solar cell with high power generation efficiency can be provided.

FIG. 1 is a schematic cross-sectional view of a general solar cell.

  The solar cell sealing film of the present invention includes an ethylene-polar monomer copolymer, a silane coupling agent (A) having an aminoalkyl group at the terminal, and a silane coupling agent (B) having no amino group. Yes. And content of a silane coupling agent (A) is 0.01-1.0 mass part with respect to 100 mass parts of ethylene-polar monomer copolymers. When the sealing film contains the silane coupling agent (A), it is possible to prevent a decrease in insulation even under a high temperature environment, and the silane coupling agent (A) and the silane coupling agent (B). By containing both, yellowing can be prevented and adhesion can be improved.

  The cause of the decrease in electrical insulation due to the use of the silane coupling agent (A) is not clear, but the amino structure of the aminoalkyl group traps ions, thereby suppressing the movement of ions in the sealing film. This is thought to be due to

  Hereinafter, the solar cell sealing film of the present invention will be described in more detail.

(Silane coupling agent (A))
The silane coupling agent (A) may be any silane coupling agent having an aminoalkyl group at the terminal. Preferably, it is a silane coupling agent represented by the above formula (1). In the above formula (1), R ¹ , R ² and R ³ are alkyl groups, R ⁴ is a hydrogen atom or an aminoalkyl group, and n is an integer of 1 to 6. The alkyl group is, for example, a methyl group, an ethyl group, or a propyl group, and R ¹ , R ^2, and R ³ may be the same or different. The aminoalkyl group is, for example, an aminomethyl group, an aminoethyl group, or an aminopropyl group.

  Examples of the silane coupling agent (A) include N-2 (aminoethyl) -3-aminopropylmethyldimethoxysilane, N-2 (aminoethyl) -3-aminopropyltrimethoxysilane, N-2- (aminoethyl). ) -3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane and the like. In particular, N-2 (aminoethyl) -3-aminopropyltrimethoxysilane is preferable. These silane coupling agents (A) may be used alone or in combination of two or more.

In the solar cell sealing film of the present invention, the content of the silane coupling agent (A) is 0.12 to 0.5 parts by mass with respect to 100 parts by mass of the ethylene-polar monomer copolymer , and from 0.12 to 0.3 parts by weight is preferred. If the blending amount of the silane coupling agent (A) is too small, the effect of suppressing the decrease in electrical insulation may not be sufficiently obtained. If the blending amount is too large, the bleed out, resulting in resistance than expected. A value may fall or a sealing film may turn yellow.

(Silane coupling agent (B))
The silane coupling agent (B) may be a silane coupling agent having no amino group. This is because the sealing film may turn yellow when it has an amino group. For example, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane γ-chloropropyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltrichlorosilane, vinyltriacetoxysilane, 3-glycid Xylpropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane and the like. . In particular, 3-methacryloxypropyltrimethoxysilane or 3-methacryloxypropylmethyldimethoxysilane is preferable. These silane coupling agents (B) may be used alone or in combination of two or more. The amount of the silane coupling agent (B) is an ethylene - a 0.12 to 1.9 parts by weight with respect to the polar monomer copolymer 100 parts by weight, particularly from 0.12 to 1.0 parts by weight Preferably, 0.15-1.0 mass part is further preferable.

(Ethylene-polar monomer copolymer)
In the present invention, examples of the polar monomer of the ethylene-polar monomer copolymer include an unsaturated carboxylic acid, a salt thereof, an ester thereof, an amide thereof, a vinyl ester, 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, it is preferable to use a copolymer having a melt flow rate defined by JIS K7210 of 35 g / 10 min or less, particularly 3 to 6 g / 10 min. According to the sealing film for solar cells using the ethylene-polar monomer copolymer having such a melt flow rate, the sealing film is melted or positioned at the time of heating and pressing in the sealing process at the time of manufacturing the solar battery. It is possible to suppress the occurrence of deviation and the protrusion from the end of the substrate.

  In the present invention, the value of the melt flow rate (MFR) is measured based on conditions of 190 ° C. and a load of 21.18 N according to JIS K7210.

  As the ethylene-polar monomer copolymer, an ethylene-vinyl acetate copolymer (also referred to as EVA) is particularly preferable. Thereby, it is cheap and can form the sealing film for solar cells which is 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 sealing film obtained when crosslinked and cured at a high temperature may not be sufficiently transparent. If it exceeds 35% by mass, carboxylic acid, alcohol, amine May occur, and foaming may easily occur at the interface between the sealing film and the protective member.

  In addition to the ethylene-polar monomer copolymer, the solar cell encapsulating film of the present invention further comprises a polyvinyl acetal resin (for example, polyvinyl formal, polyvinyl butyral (PVB resin), modified PVB), and a vinyl chloride resin. May be used for In that case, PVB is particularly preferable.

(Crosslinking agent)
In the present invention, the crosslinking agent is capable of forming a crosslinked structure of an ethylene-polar monomer copolymer. As the crosslinking agent, an organic peroxide or a photopolymerization initiator is preferably used. Among them, it is preferable to use an organic peroxide because a sealing film having improved temperature dependency of adhesive strength, transparency, moisture resistance, and penetration resistance can be 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. 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.

  As the photopolymerization initiator, any known photopolymerization initiator can be used, but a photopolymerization initiator having good storage stability after blending is desirable. Examples of such a photopolymerization initiator include 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, and 2-methyl-1- (4- (methylthio) phenyl). Acetophenones such as -2-morpholinopropane-1, benzoins such as benzyldimethylketal, benzophenones such as benzophenone, 4-phenylbenzophenone and hydroxybenzophenone, thioxanthones such as isopropylthioxanthone and 2-4-diethylthioxanthone, As other special ones, methylphenylglyoxylate can be used. Particularly preferably, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- (4- (methylthio) phenyl) -2-morpholinopropane-1, Examples include benzophenone. These photopolymerization initiators may contain one or two or more kinds of known and commonly used photopolymerization accelerators such as benzoic acid-based or tertiary amine-based compounds such as 4-dimethylaminobenzoic acid as required. Can be mixed and used. Moreover, it can be used individually by 1 type of only a photoinitiator, or 2 or more types of mixture.

  It is preferable that content of the said photoinitiator is 0.5-5.0 mass parts with respect to 100 mass parts of ethylene-polar monomer copolymers.

(Crosslinking aid)
Furthermore, it is preferable that the sealing film for solar cells before crosslinking curing contains a crosslinking aid. The crosslinking aid can improve the crosslinking density of the ethylene-polar monomer copolymer and form a solar cell sealing film having a low degree of swelling after crosslinking and curing.

  The crosslinking aid is preferably used in an amount of 0.1 to 3.0 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. With such a content of the crosslinking aid, there is no generation of gas due to the addition of the crosslinking aid, and the crosslinking density of the ethylene-polar monomer copolymer can be improved.

  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). Etc.) of monofunctional or bifunctional crosslinking aids. Of these, triallyl cyanurate and / or triallyl isocyanurate are preferable, and triallyl isocyanurate is particularly preferable.

(Other)
The sealing film of the present invention is used to improve or adjust various physical properties of the film (optical properties such as mechanical strength and transparency, heat resistance, light resistance, crosslinking speed, etc.), particularly for improving mechanical strength. If necessary, 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.

  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 diptanoate, and triethylene glycol dipelargonate. One plasticizer may be used, or two or more plasticizers 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 methyl, ethyl, dodecyl, stearyl, lauryl and other linear alkyl groups, cyclohexyl group, tetrahydrofurfuryl group, aminoethyl group, 2-hydroxyethyl group, 3-hydroxypropyl group, A 3-chloro-2-hydroxypropyl group can be mentioned. 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, 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, the solar cell sealing film of the present invention may contain a light stabilizer and / or an anti-aging agent.

  By containing the light stabilizer, it is possible to suppress deterioration of the ethylene-polar monomer copolymer due to the influence of the irradiated light and the like, and the yellowing of the solar cell sealing film. 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 of which are ADEKA) , Tinuvin 744, Tinuvin 770, Tinuvin 765, Tinuvin 144, Tinuvin 622LD, CHIMASSORB 944LD (all manufactured by Ciba Specialty Chemicals), UV-3034 (manufactured by BF Goodrich), and the like. . 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 anti-aging agent include lactone heat stabilizers, vitamin E heat stabilizers, sulfur heat stabilizers and the like in addition to the above antioxidants.

  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, the composition containing each of the above-described components can be produced by a method of obtaining a sheet-like material by molding by ordinary extrusion molding, calendar molding (calendering) or the like. 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 thickness of the solar cell sealing film is not particularly limited, but may be in the range of 50 μm to 2 mm.

  In the solar cell, in order to sufficiently seal the solar cell, as shown in FIG. 1, the surface side transparent protective member 11, the surface side sealing film 13A, the solar cell 14 and the back surface side sealing film 13B. And the back surface side protection member 12 may be laminated | stacked, and the sealing film should just be bridge | crosslinked and hardened | cured according to conventional methods, such as heating and pressurization.

For the heating and pressurization, for example, the laminate is heated with a vacuum laminator at a temperature of 80 to 150 ° C., a degassing time of 0.1 to 5 minutes, a pressing pressure of 0.1 to 1.5 kg / cm ² , and a pressing time of 5 to 5. What is necessary is just to heat-press in 15 minutes. By crosslinking the ethylene-vinyl acetate copolymer contained in the front side sealing film 13A and the back side sealing film 13B during the heating and pressurization, the front side sealing film 13A and the back side sealing film 13B are interposed. And the surface side transparent protection member 11, the back surface side transparent member 12, and the cell 14 for solar cells can be integrated, and the cell 14 for solar cells can be sealed.

The solar cell sealing film of the present invention is not limited to a solar cell using a single crystal or polycrystalline silicon crystal solar cell as shown in FIG. It can also be used for sealing films of thin film solar cells such as solar cells and copper indium selenide (CIS) solar cells. In this case, for example, the solar cell of the present invention is formed on a thin film solar cell element layer formed by a chemical vapor deposition method or the like on the surface of a surface side transparent protective member such as a glass substrate, a polyimide substrate, or a fluororesin transparent substrate. On the solar cell element formed on the surface of the back surface side protective member , the structure for laminating the battery sealing film and the back surface side protective member and adhering and integrating them, the front surface side Laminated transparent protective member, bonded and integrated structure, or front side transparent protective member, front side sealing film, thin film solar cell element, back side sealing film, and back side protective member are laminated in this order, For example, a structure that is bonded and integrated.

  In addition, in this invention, the side (light-receiving surface side) by which the light of a photovoltaic cell is irradiated is called "front surface side", and the surface opposite to the light-receiving surface of a photovoltaic cell is called "back surface side."

  The surface side transparent protective member 11 used in 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 12 used in the present invention is a plastic film such as polyethylene terephthalate (PET), but in consideration of heat resistance and heat and moisture resistance, it is a fluorinated polyethylene film, particularly a fluorinated polyethylene film / Al / fluorinated. A film in which polyethylene films are laminated in this order is preferable.

  In addition, the solar cell (including a thin film solar cell) of the present invention is characterized by a sealing film used on the front surface side and / or the back surface side as described above. Therefore, the members other than the sealing film such as the front-side transparent protective member, the back-side protective member, and the solar cell need only have the same configuration as the conventionally known solar cell, and are not particularly limited. .

Hereinafter, the present invention will be described with reference to examples.
(Example 1-11 and Comparative Example 1 to 20)
Each material was supplied to a roll mill with each formulation shown in Tables 1 to 4 and kneaded at 60 to 100 ° C. to prepare a solar cell sealing film composition. The solar cell sealing film composition was press-molded at 60 to 100 ° C., allowed to cool, and then a solar cell sealing film (thickness 0.5 mm) was produced.

(1) Volume resistivity value A sample having a size of 100 mm × 100 mm was prepared for the produced sealing film for solar cell, and using two release PETs, release PET / solar cell sealing film / separation Lamination was performed in the order of mold PET. The obtained laminate was temporarily pressure-bonded at 100 ° C. for 10 minutes under vacuum with a vacuum laminator, and then heated in an oven at 150 ° C. for 30 minutes for crosslinking.

  About each produced sample, a volume resistivity (Log (ohm)) is respectively 25 degreeC and 60 degreeC environment using a high resistivity (Hiresta UP (made by Mitsubishi Chemical Corporation)) and a probe (UR-100 (made by Mitsubishi Chemical Corporation)). Cm) was measured (applied voltage, 1000 V x 1 minute). With reference to the volume resistivity of silicon resin, which has a small decrease in electrical insulation even in a high temperature environment, 15.2 or more in a 25 ° C. environment, 14.5 or more in a 60 ° C. environment (these values are referred to as reference values) Was accepted).

(2) Glass adhesive force The solar cell sealing film produced above was sandwiched between release PET (75 μm) and white glass (3.2 mm thickness), and was temporarily pressure-bonded at 100 ° C. for 10 minutes with a vacuum laminator. Thereafter, it was placed in an oven and heated at 150 ° C. for 30 minutes for crosslinking. In this laminate, a part between the sealing film and the white glass was peeled off, and the sealing film (width 25 mm) was folded back at 180 ° C. to obtain a tensile tester (Autograph AG-10KN (manufactured by Shimadzu Corporation)). Was used to measure the peel strength at a tensile strength of 100 mm / min as the glass adhesive strength [N / cm]. The criterion for determining the adhesive force was 10 N / cm or more as acceptable.

(3) Yellowing degree The above solar cell sealing film was sandwiched between two pieces of white glass (3.0 mm thick), temporarily bonded at 100 ° C. for 10 minutes with a vacuum laminator, placed in an oven, and 30 at 150 ° C. Heated for minutes to crosslink.

Using this s-UV irradiation tester (eye super UV tester (manufactured by Iwasaki Electric Co., Ltd.)), the laminate was irradiated with ultraviolet rays having an ultraviolet intensity of 295 to 400 nm of 100 mW / cm ² for 120 hours in an environment of 63 ° C. did. Using a color difference meter (color computer SM-5-IS-2B, manufactured by Suga Test Instruments Co., Ltd.), the difference in yellowing degree (ΔYI) of the laminate before and after ultraviolet irradiation was measured in JIS-K-7105 (1981). Measurements were made in accordance with light resistance. Less than 2.0 was accepted.

  In addition, the laminate was allowed to stand for 1000 hours in an environment conforming to JIS-C-8917 (temperature: 85 ° C.), and the difference in YI values before and after being left (ΔYI value) was measured in the same manner as described above to determine the heat resistance. Examined. A value of less than 4.0 was accepted.

(Evaluation results)
The result of said each evaluation is shown to Tables 1-4.
In Examples 1 to 11 , various silane coupling agents (A) were blended in amounts in Tables 1 and 2 with respect to 100 parts by mass of EVA, and the produced sealing films for solar cells were evaluated. As a result, the volume resistivity value exceeded the reference value in a 25 ° C. environment and a 60 ° C. environment. Moreover, the glass adhesive force and the yellowing degree were also acceptable. In addition, “> 16.7” in the table indicates that the upper limit (16.7) of the measuring apparatus has been exceeded.

Next, in Examples 10 and 11 , when the solar cell sealing film produced by changing the blending amount of the silane coupling agent B with 0.5 parts by mass of the silane coupling agent A (1) was evaluated. All the evaluation items were acceptable.

  In Comparative Examples 1 to 3, in place of the various silane coupling agents (A) used in the Examples, another silane coupling agent having no aminoalkyl group at the terminal as a comparison target is considered to be the optimum amount. .5 parts by mass was similarly evaluated. As a result, the volume resistivity (log (Ω · cm)) at 60 ° C. did not satisfy the standard value for all three types.

  Moreover, in Comparative Examples 4-7, the various silane coupling agents (A) used in the Example with respect to 100 parts by mass of EVA were blended by changing the blending amount (1.3 parts by mass), and the resulting sun The battery sealing film was evaluated. As a result, the volume resistivity (log (Ω · cm)) did not satisfy the standard value.

  Comparative Examples 8 to 11 are comparative examples in which the silane coupling agents A and B were not used in combination. Each of the evaluation items could not be satisfied, and the determination was x.

By the above, EVA, the silane coupling agent (A) which has an aminoalkyl group at the terminal containing the silane coupling agent (A) which has an aminoalkyl group at the terminal, and the silane coupling agent (B) which does not have an amino group However, if the sealing film is 0.12 to 0.5 parts by mass with respect to 100 parts by mass of EVA, it was shown that the decrease in insulation under a high temperature environment is suppressed.

  According to the present invention, it is possible to provide a solar cell sealing film in which a decrease in insulating properties under a high temperature environment is suppressed, adhesion is improved, and yellowing does not occur.

DESCRIPTION OF SYMBOLS 11 Surface side transparent protective member 12 Back surface side protective member 13A Surface side sealing film 13B Back surface side sealing film 14 Cell for solar cells

Claims (7)

An encapsulating film for solar cells containing an ethylene-polar monomer copolymer and a silane coupling agent,
The silane coupling agent comprises a silane coupling agent (A) having an aminoalkyl group at the terminal and a silane coupling agent (B) having no amino group, and the content of the silane coupling agent (A) is the ethylene - against polar monomer copolymer 100 parts by weight of 0.12 to 0.5 parts by mass der is, the content of the silane coupling agent (B), the ethylene - polar monomer copolymer per 100 parts by weight, the sealing film for a solar cell, wherein 0.12 to 1.9 parts by der Rukoto. The silane coupling agent (A) is represented by the following formula (1)

(Wherein R ¹ , R ² , and R ³ are alkyl groups, R ⁴ is a hydrogen atom or an aminoalkyl group, and n is an integer of 1 to 6). The sealing film for solar cells of Claim 1. The silane coupling agent (A) is, N-2 (aminoethyl) -3-aminopropyltrimethoxysilane, N-2 (aminoethyl) -3-aminopropyl-di methoxide shish run, 3-aminopropyl trimethoxysilane And the sealing film for solar cells according to claim 1, which is selected from the group consisting of 3-aminopropyltriethoxysilane. The solar cell sealing according to any one of claims 1 to 3, wherein the silane coupling agent (A) is N-2 (aminoethyl) -3-aminopropyltrimethoxysilane. film. The silane coupling agent (B), 3-methacryloxypropyl trimethoxy silane or 3-methacryloxypropyl The solar cell sealing film according to any one of claims 1-4 is methyl dimethoxy silane.   The solar cell sealing film according to any one of claims 1 to 5, wherein the ethylene-polar monomer copolymer is an ethylene-vinyl acetate copolymer.   The solar cell using the sealing film for solar cells of any one of Claims 1-6.

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