JP2010226041A - Solar cell module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solar cell module reducing contamination of a vacuum pump of a vacuum laminator, and achieving excellent balancing between a creep resistance and a gap filling ability. <P>SOLUTION: The solar cell module 1 is formed by sealing solar cells between a transparent insulating substrate 2 and a rear insulating substrate 3 with a resin sealing sheet. In this case, only one of the two resin sealing sheets 5A and 5B neighboring to the solar cells is crosslinked. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a solar cell module.

  In recent years, the global warming phenomenon has heightened awareness of the environment, and a new energy system that does not generate greenhouse gases such as carbon dioxide is attracting attention. Since the energy generated by solar cell power generation does not emit carbon dioxide and other gases that cause global warming, research and development has been conducted as clean energy, and has attracted attention as industrial energy. Representative examples of solar cells include those using single crystal and polycrystalline silicon cells (crystalline silicon cells), those using amorphous silicon, and compound semiconductors (thin film cells). Solar cells are often used outdoors for a long period of time by being exposed to wind and rain, and the power generation part is modularized by laminating a glass plate or back sheet to prevent moisture from entering from outside. It was intended to protect and prevent leakage. The member that protects the power generation portion uses transparent glass or transparent resin on the light incident side in order to ensure light transmission necessary for power generation. For the member on the opposite side, an aluminum foil called a back sheet, a polyvinyl fluoride resin (PVF), polyethylene terephthalate (PET), or a laminated sheet of a barrier coating such as silica is used. The power generation element is sandwiched between resin sealing sheets, the outside is further covered with glass or a back sheet, heat treatment is performed to melt the resin sealing sheet, and the whole is integrally sealed (modularized).

  The following (1) to (3) are required as characteristics of the resin-encapsulated sheet described above. (1) Good adhesion to glass, power generation element and back sheet, (2) Flow prevention (creep resistance) of power generation element due to melting of resin-sealed sheet at high temperature, (3) Transparency that does not hinder the incidence of sunlight. From this point of view, the resin-encapsulated sheet is made of an ethylene-vinyl acetate copolymer (hereinafter also abbreviated as EVA), an ultraviolet absorber as a measure against ultraviolet deterioration, a coupling agent for improving adhesion to glass, For crosslinking, additives such as organic peroxides are blended, and the film is formed by calendar molding or T-die casting. In view of exposure to sunlight over a long period of time, various additives such as a light-resistant agent are blended in order to prevent deterioration of optical properties due to deterioration of the resin. Thereby, the transparency which does not inhibit the incidence of sunlight for a long time is maintained.

  As a form of modularizing solar cells with the resin-encapsulated sheet as described above, glass / resin encapsulated sheet / power generation element such as crystalline silicon cell / resin encapsulated sheet / back sheet are stacked in this order, and the glass surface is Using a dedicated solar cell vacuum laminator, the resin sealing sheet is melted and pasted through a step of preheating above the melting temperature of the resin (temperature condition of 150 ° C in the case of EVA) and a pressing step. There is. In this method, first, the resin of the resin sealing sheet is melted in the preheating process, and is in close contact with the member in contact with the melted resin in the pressing process and vacuum laminated. In this laminating step, (i) a crosslinking agent contained in the resin sealing sheet, for example, an organic peroxide, is thermally decomposed to promote EVA crosslinking. (Ii) It is covalently bonded to the member in contact with the coupling agent contained in the resin sealing sheet. This improves the mutual adhesion, prevents the flow of the power generation part due to melting of the resin encapsulated sheet at high temperature (creep resistance), and excellent adhesion to glass, power generation element, and back sheet Is realized.

Patent Document 1 discloses a solar cell filling adhesive sheet made of an ethylene copolymer resin containing a coupling agent and an organic peroxide.
Patent Document 2 discloses a sheet for sealing a solar cell, which is a sheet made of an ethylene vinyl acetate copolymer blended with a crosslinking agent and a silane coupling agent, and is radiation-crosslinked to a certain gel fraction. Is disclosed.
In the above document, after stacking each member such as glass, sealing sheet, cell, back sheet, etc., a solar cell module is manufactured by performing melt bonding and crosslinking with organic peroxide using a vacuum laminator. ing.

JP 58-060579 A JP-A-8-283696

The solar cell module disclosed in the above document imparts creep resistance by crosslinking both of the two sealing sheets adjacent to the solar cell with an organic peroxide in a vacuum laminator. However, the crosslinking with the organic peroxide has a problem that the vacuum pump of the vacuum laminator is contaminated with a gas such as carbon monoxide or carbon dioxide generated when the organic peroxide is thermally decomposed. Moreover, in order to give creep resistance to the module, when both of the two sealing sheets adjacent to the solar battery cell are highly crosslinked, the steps such as the solar battery cell and the wiring are sealed without gaps, That is, there is a possibility that the gap filling property is insufficient.

  In view of the above circumstances, the problem to be solved by the present invention is to provide a solar cell module that reduces contamination of the vacuum pump of the vacuum laminator and has an excellent balance of creep resistance and gap filling properties.

As a result of intensive studies on the above problems, the present inventors have found a solar cell module in which solar cells are sealed with a resin sealing sheet between a translucent insulating substrate and a back insulating substrate. Thus, the present inventors have found that a solar cell module in which only one of the two resin-encapsulated sheets adjacent to the solar cell is cross-linked can solve the above-mentioned problems, and has completed the present invention.

That is, the present invention is as follows.
[1]
A solar cell module formed by sealing solar cells between a translucent insulating substrate and a back insulating substrate with a resin sealing sheet,
A solar cell module in which only one of the two resin-encapsulated sheets adjacent to the solar cell is crosslinked.
[2]
Of the two resin-encapsulated sheets adjacent to the solar battery cell, only the resin-encapsulated sheet on the back insulating substrate side is crosslinked, and the solar cell module according to [1].
[3]
The solar cell module according to [1] or [2], wherein the resin sealing sheet is subjected to a crosslinking treatment with ionizing radiation.
[4]
The resin-encapsulated sheet includes an ethylene-vinyl acetate copolymer, an ethylene-aliphatic unsaturated carboxylic acid copolymer, an ethylene-aliphatic carboxylic acid ester copolymer, an ethylene-vinyl acetate copolymer saponified product, an ethylene- The solar cell module according to any one of the above [1] to [3], which contains at least one resin selected from the group consisting of a vinyl acetate-acrylic acid ester copolymer saponified product and a polyolefin resin.

  According to the present invention, it is possible to provide a solar cell module that can reduce contamination of a vacuum pump of a vacuum laminator and has an excellent balance of creep resistance and gap filling properties.

It is the figure which showed typically sectional drawing of the solar cell module in this Embodiment.

  Hereinafter, a mode for carrying out the present invention (hereinafter referred to as “the present embodiment”) will be described in detail. In addition, this invention is not limited to the following embodiment, It can implement by changing variously within the range of the summary.

  The solar cell module in the present embodiment is a solar cell module formed by sealing a solar cell between a translucent insulating substrate and a back insulating substrate with a resin sealing sheet, and is adjacent to the solar cell. This is a solar cell module in which only one of the two resin encapsulating sheets is cross-linked.

  FIG. 1 is a diagram schematically showing a cross-sectional view of the solar cell module in the present embodiment. As shown in FIG. 1, a solar cell module 1 according to the present embodiment is formed by sandwiching and stacking solar cells 4 formed of crystalline silicon or the like between two or more resin-encapsulated sheets 5A and 5B, and further transparent the surface. The optical insulating substrate 2 has a structure in which the back surface is covered with the back insulating substrate 3. That is, it has the structure of translucent insulating substrate 2 / resin sealing sheet 5A / solar battery cell 4 / resin sealing sheet 5B / back surface insulating substrate 3. However, since the configuration shown in FIG. 1 is one of the preferred embodiments, the solar cell module of the present embodiment is not limited to the above-described configuration, and layers other than those described above are provided as long as the object of the present invention is not impaired. It can be provided as appropriate. Typically, an adhesive layer, a shock absorbing layer, a coating layer, an antireflection layer, a back surface rereflection layer, a light diffusion layer, and the like can be provided, but not limited thereto. The position where these layers are provided is not particularly limited, and can be provided at an appropriate position in consideration of the purpose of providing such layers and the characteristics of such layers.

  The solar cell module in the present embodiment is one in which only one of the two resin sealing sheets 5A and 5B adjacent to the solar cell 4 shown in FIG. 1 is cross-linked. Usually, a solar cell module is formed by laminating two sealing sheets in an uncrosslinked state and integrating them with a vacuum laminator, and then performing a crosslinking treatment with an organic peroxide in a curing furnace to suppress creep at a high temperature ( The present inventors have found that sufficient creep resistance can be achieved by crosslinking only one of the two resin-encapsulated sheets adjacent to the cell. Furthermore, when crosslinking is performed using an organic peroxide, the amount of gas generated when the organic peroxide is thermally decomposed can be reduced, so that corrosion damage and oil contamination of the vacuum laminator vacuum pump can be suppressed. I understood.

  In the solar cell module in the present embodiment, among the two resin encapsulating sheets adjacent to the solar cell, only the resin encapsulating sheet on the back insulating substrate side (resin encapsulating sheet 5B in FIG. 1) is used. More preferably it is cross-linked. When only the resin sealing sheet on the back insulating substrate side is cross-linked, the creep resistance and gap filling property tend to be better.

  The resin encapsulated sheet is “crosslinked” means that the gel fraction is preferably 3% by mass or more as a result of physically and chemically crosslinking the polymer constituting the resin by a known method. Say. The gel fraction of the crosslinked resin encapsulating sheet of the two resin encapsulating sheets adjacent to the solar battery cell is preferably 3 to 90% by mass, more preferably 3 to 86% by mass, and still more preferably 5 -80 mass%. The non-crosslinked resin encapsulated sheet refers to a sheet that is not substantially crosslinked, and the gel fraction thereof is preferably less than 3% by mass, more preferably less than 1% by mass, and still more preferably. Is 0% by mass. When the gel fraction of the two resin-encapsulated sheets adjacent to the solar battery cells is in the above range, the solar battery module tends to be excellent in the balance between creep resistance and gap filling ability. In addition, even if it is a case where the resin sealing sheet has either a single layer structure or a multilayer structure described later, the gel fraction is the average gel fraction of the entire resin sealing sheet (total layer gel fraction). ) Value.

  As a method for crosslinking the resin-encapsulated sheet, a known method can be used without limitation. For example, a crosslinking treatment with an organic peroxide or a crosslinking treatment by irradiation with ionizing radiation (electron beam, γ ray, ultraviolet ray, etc.) These may be used in combination.

  In the case of crosslinking by irradiation with ionizing radiation, a method of irradiating the resin encapsulating sheet with ionizing radiation such as α-ray, β-ray, γ-ray, neutron beam, electron beam, etc. to cross-link can be mentioned. The acceleration voltage of ionizing radiation such as an electron beam may be selected according to the thickness of the resin sealing sheet. For example, when the thickness is 500 μm, when the entire resin sealing sheet is crosslinked, the acceleration voltage is 300 kV or more. is necessary.

  The acceleration voltage of ionizing radiation such as an electron beam can be appropriately adjusted according to the resin layer subjected to the crosslinking treatment. The irradiation dose of ionizing radiation varies depending on the resin used, but is generally less than 3 kGy. It tends to be difficult to uniformly cross-link the entire resin-encapsulated sheet.

  The accelerating voltage and irradiation dose of ionizing radiation can be appropriately adjusted in order to obtain a desired gel fraction. The degree of crosslinking can be evaluated by measuring the gel fraction.

  In order to achieve the gel fraction in the above range, in addition to the irradiation amount of ionizing radiation, the difference in the degree of crosslinking depending on the type of resin, or the effect of crosslinking promotion or crosslinking inhibition by a transfer agent or the like may be utilized. .

  In the case of crosslinking with an organic peroxide, thermal crosslinking is performed by blending or impregnating the organic peroxide in the resin as a crosslinking agent. In this case, an organic peroxide having a half-life at 100 to 130 ° C. of 1 hour or less is preferable.

  Examples of organic peroxides that have good compatibility and have the above half-life include 1,1-bis (t-butylperoxy) 3,3,5-trimethylcyclohexane, 1,1 -Bis (t-butylperoxy) cyclohexane, n-butyl-4,4-bis (t-butylperoxy) valerate, 2,2-bis (t-butylperoxy) butane and the like. The resin-encapsulated sheet using these organic peroxides can reduce the crosslinking time relatively, and the curing process is an organic material having a half-life at 100 to 130 ° C., which is conventionally used, of 1 hour or more. Compared with the case of using a peroxide, it can be shortened to about half.

  The content of the organic peroxide is preferably 0 to 10% by mass and more preferably 0 to 5% by mass with respect to the resin constituting the resin sealing sheet.

  The resin-encapsulated sheet containing the organic peroxide is softened during lamination, and after the gap is filled, the decomposition and crosslinking of the organic peroxide are promoted, so the resin gel fraction increases. However, it has an advantage that the gap filling property is not hindered.

  As described above, “crosslinking” includes a method of irradiating with ionizing radiation and a method of using an organic peroxide, and a method of crosslinking by irradiation with ionizing radiation is particularly preferable. The crosslinking treatment by irradiation with ionizing radiation does not generate gas due to thermal decomposition of the organic peroxide, and therefore tends to further reduce the corrosion damage and oil contamination of the vacuum pump. In addition, the crosslinking method using an organic peroxide requires a long curing process for decomposing the organic peroxide in the lamination process and promoting the crosslinking of the resin sealing sheet. Although it is difficult to speed up production, the crosslinking method by irradiation with ionizing radiation is excellent in that it does not require a long-time curing step and can improve the productivity of the solar cell module.

[Resin sealing sheet]
The resin encapsulating sheet softens the resin by a method of directly giving energy such as heat to the resin component or a method of giving a vibration inherent to the resin component to generate heat of the resin itself. A substance can be adhered and sealed. As a method for softening the resin, a known method using direct heating to the resin component, indirect heat such as radiant heat, vibrational heat generation such as ultrasonic waves, or the like can be used.

  The resin constituting the resin encapsulating sheet is not particularly limited as long as it is a resin that is crosslinked by an organic peroxide or ionizing radiation, but has good transparency, flexibility, adhesion and handling properties of an adherend. From the viewpoint of securing, ethylene-vinyl acetate copolymer, ethylene-aliphatic unsaturated carboxylic acid copolymer, ethylene-aliphatic carboxylic acid ester copolymer, saponified ethylene-vinyl acetate copolymer, ethylene-vinyl acetate -It is preferable to contain at least 1 sort (s) of resin selected from the group which consists of saponified acrylate copolymer and polyolefin resin.

  The ethylene-vinyl acetate copolymer refers to a copolymer obtained by copolymerization of an ethylene monomer and vinyl acetate. The ethylene-aliphatic unsaturated carboxylic acid copolymer refers to a copolymer obtained by copolymerization of an ethylene monomer and at least one monomer selected from aliphatic unsaturated carboxylic acids. Furthermore, the ethylene-aliphatic unsaturated carboxylic acid ester copolymer refers to a copolymer obtained by copolymerization of an ethylene monomer and at least one monomer selected from aliphatic unsaturated carboxylic acid esters.

  The copolymerization can be performed by a known method such as a high pressure method or a melting method, and a multisite catalyst, a single site catalyst, or the like can be used as a catalyst for the polymerization reaction. Moreover, in the said copolymer, the bond shape of each monomer is not specifically limited, The polymer which has bond shapes, such as a random bond and a block bond, can be used. From the viewpoint of optical properties, the copolymer is preferably a copolymer polymerized by random bonding using a high-pressure method.

  In the ethylene-vinyl acetate copolymer, the ratio of vinyl acetate in all monomers constituting the copolymer is preferably 10 to 40% by mass from the viewpoint of optical properties, adhesiveness, and flexibility. More preferably, it is -35 mass%, and it is still more preferable that it is 15-30 mass%. Further, from the viewpoint of workability of the resin-encapsulated sheet, a melt flow rate value (hereinafter also abbreviated as “MFR”) (190 ° C., 2.16 kg) measured according to JIS-K-7210 is obtained. It is preferably 0.3 g / 10 min to 30 g / 10 min, more preferably 0.5 g / min to 30 g / min, and still more preferably 0.8 g / min to 25 g / min.

  Examples of the ethylene-aliphatic unsaturated carboxylic acid copolymer include an ethylene-acrylic acid copolymer (hereinafter also abbreviated as “EAA”) and an ethylene-methacrylic acid copolymer (hereinafter, “EMAA”). Abbreviated as well)). Examples of the ethylene-aliphatic unsaturated carboxylic acid ester copolymer include an ethylene-acrylic acid ester copolymer and an ethylene-methacrylic acid ester copolymer. Here, as acrylic acid ester and methacrylic acid ester, ester with C1-C8 alcohols, such as methanol and ethanol, is used suitably.

  These copolymers may be multi-component copolymers obtained by copolymerizing three or more monomers. Examples of the multi-component copolymer include a copolymer obtained by copolymerizing at least three types of monomers selected from ethylene, aliphatic unsaturated carboxylic acid, and aliphatic unsaturated carboxylic acid ester.

  In the ethylene-aliphatic unsaturated carboxylic acid copolymer, the proportion of the aliphatic unsaturated carboxylic acid in all monomers constituting the copolymer is preferably 3 to 35% by mass. Further, MFR (190 ° C., 2.16 kg) is preferably 0.3 g / 10 min to 30 g / 10 min, more preferably 0.5 g / 10 min to 30 g / 10 min, and 0.8 g / 10 min to More preferably, it is 25 g / 10 min.

  Examples of the saponified ethylene-vinyl acetate copolymer include a partially or completely saponified ethylene-vinyl acetate copolymer, and examples of the saponified ethylene-vinyl acetate-acrylic acid ester copolymer include ethylene- Examples thereof include a vinyl acetate-acrylic acid ester copolymer part or a completely saponified product.

  The ratio of the hydroxyl group in each saponified product is preferably 0.1% by mass to 15% by mass, more preferably 0.1% by mass to 10% by mass, in the resin constituting the resin sealing sheet. More preferably, it is 0.1 mass%-7 mass%. If the proportion of the hydroxyl group is 0.1% by mass or more, the adhesiveness tends to be good, and if it is 15% by mass or less, the compatibility tends to be good. The risk of clouding can be reduced.

  The ratio of the hydroxyl group was determined based on the olefin-based polymer resin of the saponified ethylene-vinyl acetate copolymer and the saponified ethylene-vinyl acetate-acrylic acid ester copolymer, and VA% of this resin (vinyl acetate copolymer by NMR measurement). (Polymerization ratio), its saponification degree, and the blending ratio in the resin.

  The content of vinyl acetate in the ethylene-vinyl acetate copolymer and the ethylene-vinyl acetate-acrylic acid ester copolymer before saponification is determined from the viewpoint of obtaining good optical properties, adhesiveness, and flexibility. It is preferable that it is 10-40 mass% with respect to the whole union, it is more preferable that it is 13-35 mass%, and it is still more preferable that it is 15-30 mass%. The saponification degree of the saponified ethylene-vinyl acetate copolymer and the saponified ethylene-vinyl acetate-acrylic acid ester copolymer is 10 to 70% from the viewpoint of obtaining good transparency and adhesiveness. Is more preferable, 15 to 65% is more preferable, and 20 to 60% is still more preferable.

  Examples of the saponification method include a method of saponifying an ethylene-vinyl acetate copolymer, an ethylene-vinyl acetate-acrylic ester copolymer pellet or powder using an alkali catalyst in a lower alcohol such as methanol, toluene, And a method of dissolving a copolymer in advance using a solvent such as xylene and hexane and then saponifying using a small amount of alcohol and an alkali catalyst. Moreover, you may graft-polymerize the monomer containing functional groups other than a hydroxyl group to the saponified copolymer.

  Since each saponified product has a hydroxyl group in the side chain, the adhesiveness is improved as compared with the copolymer before saponification. Moreover, transparency and adhesiveness can be controlled by adjusting the amount of hydroxyl groups (degree of saponification).

  Moreover, in the resin which comprises a resin sealing sheet, the ethylene copolymer containing glycidyl methacrylate may be contained. The ethylene copolymer containing glycidyl methacrylate refers to an ethylene copolymer and an ethylene terpolymer with glycidyl methacrylate having an epoxy group as a reaction site. For example, ethylene-glycidyl methacrylate copolymer, ethylene-glycidyl methacrylate-vinyl acetate copolymer And an ethylene-glycidyl methacrylate-methyl acrylate copolymer. Since the above compounds have high reactivity of glycidyl methacrylate, they can exhibit stable adhesion, and have a low glass transition temperature and tend to have good flexibility.

  As the polyolefin resin, polyethylene resin, polypropylene resin, and polybutene resin are preferable. Here, the polyethylene resin refers to a homopolymer of ethylene or a copolymer of ethylene and one or more other monomers. The polypropylene resin refers to a homopolymer of propylene or a copolymer of propylene and one or more other monomers.

  Examples of the polyethylene resin include polyethylene and ethylene-α-olefin copolymers.

  Examples of the polyethylene include low density polyethylene (LDPE), linear low density polyethylene (LLDPE), and linear very low density polyethylene (referred to as “VLDPE” and “ULDPE”).

  The ethylene-α-olefin copolymer is preferably a copolymer composed of ethylene and at least one selected from α-olefins having 3 to 20 carbon atoms, and includes ethylene and 3 to 12 carbon atoms. More preferred is a copolymer comprising at least one selected from α-olefins. Examples of the α-olefin include propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 4-methyl-1-pentene, 3-methyl-1-pentene, 1-decene, and 1-decene. Examples include dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosane and the like, and these can be used alone or in combination. Moreover, it is preferable that the ratio (based on preparation monomer) of the alpha olefin in all the monomers which comprise a copolymer is 6-30 mass%. Further, the ethylene-α-olefin copolymer is preferably a soft copolymer, and preferably has a crystallinity of 30% or less by an X-ray method.

  In addition, as the ethylene-α-olefin copolymer, a copolymer of ethylene and at least one comonomer selected from propylene comonomer, butene comonomer, hexene comonomer, and octene comonomer is generally easily available. It can be used suitably.

The polyethylene resin can be polymerized using a known catalyst such as a single site catalyst or a multisite catalyst, and is preferably polymerized using a single site catalyst. The above polyethylene-based resin, from the viewpoint of cushioning properties, it is preferable that a density of 0.860~0.920g / cm ^3, more preferably 0.870~0.915g / cm ^3, 0. More preferably, it is 870-0.910 g / cm < ³ >. When the density is 0.920 g / cm ³ or less, the cushioning property tends to be good. If the density exceeds 0.920 g / cm ³ , the transparency may be deteriorated. When a high-density polyethylene-based resin is used, the transparency can be improved by adding a low-density polyethylene-based resin at a ratio of about 30% by mass, for example.

  The polyethylene resin preferably has an MFR (190 ° C., 2.16 kg) of 0.5 g / 10 min to 30 g / 10 min, preferably 0.8 g / 10 min to 30 g / min, from the viewpoint of processability of the resin encapsulated sheet. 10 min is more preferable, and 1.0 g / 10 min to 25 g / 10 min is still more preferable.

  As said polyethylene-type resin, the polyethylene-type copolymer which controlled crystal / amorphous structure (morphology) by nano order can also be used.

  Examples of the polypropylene resin include polypropylene, propylene-α-olefin copolymer, and terpolymer of propylene, ethylene, and α-olefin.

  The propylene-α-olefin copolymer refers to a copolymer composed of at least one selected from propylene and α-olefin. The propylene-α-olefin copolymer is preferably a copolymer composed of propylene and at least one selected from ethylene and an α-olefin having 4 to 20 carbon atoms, and propylene, ethylene and 4 to 8 carbon atoms. A copolymer comprising at least one selected from α-olefins is more preferable. Examples of the α-olefin having 4 to 20 carbon atoms include propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 4-methyl-1-pentene, and 3-methyl-1-pentene. , 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosane and the like, and these can be used alone or in combination. Moreover, it is preferable that the content rate (charged monomer reference | standard) of ethylene and / or alpha-olefin in all the monomers which comprise the said propylene-alpha-olefin copolymer is 6-30 mass%. Furthermore, the propylene-α-olefin copolymer is preferably a soft copolymer, and preferably has a crystallinity of 30% or less by an X-ray method.

  As the propylene-α-olefin copolymer, a copolymer of propylene and at least one comonomer selected from ethylene comonomer, butene comonomer, hexene comonomer, and octene comonomer is generally easily available, and preferably Can be used.

The polypropylene resin can be polymerized using a known catalyst such as a single-site catalyst or a multi-site catalyst, and is preferably polymerized using a single-site catalyst. Also the polypropylene-based resin, from the viewpoint of cushioning properties, it is preferable that a density of 0.860~0.920g / cm ^3, more preferably 0.870~0.915g / cm ^3, 0. More preferably, it is 870-0.910 g / cm < ³ >. When the density is 0.920 g / cm ³ or less, the cushioning property tends to be good. If the density exceeds 0.920 g / cm ³ , the transparency may be deteriorated.

  The polypropylene resin preferably has an MFR (230 ° C., 2.16 kgf) of 0.3 g / 10 min to 15.0 g / 10 min from the viewpoint of processability of the resin-encapsulated sheet, preferably 0.5 g / 10 min. 12 g / 10 min is more preferable, and 0.8 g / 10 min to 10 g / 10 min is still more preferable.

  As the polypropylene resin, a polypropylene copolymer in which the crystal / amorphous structure (morphology) is controlled in nano order can also be used.

  Examples of the polypropylene resin include copolymers of propylene and α-olefins such as ethylene, butene, hexene, and octene, or ternary compounds of propylene, ethylene and α-olefins such as butene, hexene, and octene. A copolymer etc. can be used conveniently. These copolymers may be in any form such as a block copolymer, a random copolymer, etc., preferably a random copolymer of propylene and ethylene, or a random copolymer of propylene, ethylene and butene. is there.

  The polypropylene resin is not limited to a resin polymerized with a catalyst such as a Ziegler-Natta catalyst, but may be a resin polymerized with a metallocene catalyst, for example, syndiotactic polypropylene, isotactic polypropylene, etc. it can. Moreover, it is preferable that the ratio (based on preparation monomer) of the propylene in all the monomers which comprise a polypropylene resin is 60-80 mass%. Furthermore, from the viewpoint of excellent heat shrinkability, the propylene content ratio (based on the charged monomer) in all monomers constituting the polypropylene resin is 60 to 80% by mass, and the ethylene content ratio (based on the charged monomer) is 10 to 30. A ternary copolymer having a butene content ratio (based on charged monomers) of 5 to 20% by mass is preferable.

  As the polypropylene resin, a resin obtained by uniformly finely dispersing a rubber component having a high concentration of 50% by mass or less with respect to the total amount of the polypropylene resin can be used.

  When the resin constituting the resin sealing sheet contains the polypropylene resin, properties such as hardness and heat resistance tend to be further improved.

  In addition, since the polybutene resin is particularly excellent in compatibility with the polypropylene resin, the polybutene resin is preferably used in combination with the polypropylene resin for the purpose of adjusting the hardness and waist of the resin sealing sheet. The polybutene resin is crystalline and is a copolymer of butene and at least one selected from ethylene, propylene and an olefin compound having 5 to 8 carbon atoms, and constitutes a polybutene resin. A high molecular weight polybutene resin having a butene content of 70 mol% or more in all monomers can be suitably used.

  The polybutene resin preferably has an MFR (190 ° C., 2.16 kg) of 0.1 g / 10 min to 10 g / 10 min. Moreover, it is preferable that a Vicat softening point is 40-100 degreeC. Here, the Vicat softening point is a value measured according to JIS K7206-1982.

The resin sealing sheet of the present embodiment may have either a single layer structure or a multilayer structure. Hereinafter, each structure will be described.
[Single layer structure]
When the resin encapsulating sheet has a single layer structure, ethylene-vinyl acetate copolymer, ethylene-aliphatic unsaturated carboxylic acid is used from the viewpoint of ensuring good transparency, flexibility, adhesion of adherends and handleability. From the group consisting of acid copolymer, ethylene-aliphatic unsaturated carboxylic acid ester copolymer, saponified ethylene-vinyl acetate copolymer, saponified ethylene-vinyl acetate-acrylic acid ester copolymer, and polyolefin resin A layer made of at least one selected resin is preferable.

  When the resin layer constituting the resin encapsulating sheet contains an ethylene-vinyl acetate copolymer saponified product or an ethylene-vinyl acetate-acrylic acid ester copolymer saponified product as an adhesive resin, the degree of saponification And content can be adjusted suitably and, thereby, adhesiveness with a to-be-sealed thing can be controlled. From the viewpoint of adhesiveness and optical properties, the content of the saponified ethylene-vinyl acetate copolymer and saponified ethylene-vinyl acetate-acrylate copolymer in the resin layer is 3 to 60% by mass. Preferably, it is 3-55 mass%, More preferably, it is 5-50 mass%.

[Multilayer structure]
The resin sealing sheet in the present embodiment may have a multilayer structure of at least two layers including a surface layer and an inner layer laminated on the surface layer. Here, the two layers forming both surfaces of the resin sealing sheet are referred to as “surface layers”, and the other layers are referred to as “inner layers”.

  In the case of having a multilayer structure, a layer containing a saponified ethylene-vinyl acetate copolymer and a saponified ethylene-vinyl acetate-acrylic acid ester copolymer as an adhesive resin is a layer in contact with an object to be sealed ( It is preferably formed as at least one surface layer. The surface layer may be a layer composed only of the saponified product described above. However, from the viewpoint of ensuring good transparency, flexibility, adhesion of the adherend and handleability, the saponified product and ethylene-vinyl acetate are used. It consists of a mixed resin with at least one resin selected from the group consisting of a copolymer, an ethylene-aliphatic unsaturated carboxylic acid copolymer, an ethylene-aliphatic unsaturated carboxylic acid ester copolymer, and a polyolefin resin. A layer is preferred.

  The layer ratio of the surface layer in contact with the object to be sealed preferably has a thickness of at least 5% with respect to the total thickness of the resin sealing sheet from the viewpoint of ensuring good adhesiveness. When the thickness is 5% or more, the same adhesiveness as in the case of the single layer structure described above tends to be obtained.

  The resin constituting the inner layer is not particularly limited, and any other resin may be used in addition to the resin contained in the surface layer described above. For the purpose of imparting other functions to the inner layer, resin materials, mixtures, additives, and the like can be appropriately selected. For example, for the purpose of newly imparting cushioning properties, a layer containing a thermoplastic resin may be provided as the inner layer.

  Examples of the thermoplastic resin used as the inner layer include polyolefin resins, styrene resins, vinyl chloride resins, polyester resins, polyurethane resins, chlorine ethylene polymer resins, polyamide resins, and the like. Those possessed and those derived from plant-derived materials are also included. Among the above, a hydrogenated block copolymer resin, a propylene copolymer resin, and an ethylene copolymer resin that have good compatibility with the crystalline polypropylene resin and good transparency are preferable, and a hydrogenated block copolymer. A resin and a propylene-based copolymer resin are more preferable.

  As the hydrogenated block copolymer resin, a block copolymer of vinyl aromatic hydrocarbon and conjugated diene is preferable. Examples of vinyl aromatic hydrocarbons include styrene, o-methylstyrene, p-methylstyrene, p-tert-butylstyrene, 1,3-dimethylstyrene, α-methylstyrene, vinylnaphthalene, vinylanthracene, and 1,1-diphenyl. Examples thereof include ethylene, N, N-dimethyl-p-aminoethylstyrene, N, N-diethyl-p-aminoethylstyrene, and styrene is particularly preferable. These may be used alone or in combination of two or more. The conjugated diene is a diolefin having a pair of conjugated double bonds, such as 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3- Examples include butadiene, 1,3-pentadiene, and 1,3-hexadiene. These may be used alone or in combination of two or more.

  As the propylene-based copolymer resin, a copolymer obtained from propylene and ethylene or an α-olefin having 4 to 20 carbon atoms is preferable. The content of the ethylene or α-olefin having 4 to 20 carbon atoms is preferably 6 to 30% by mass. Examples of the α-olefin having 4 to 20 carbon atoms include 1-butene, 1-pentene, 1-hexene, 1-octene, 4-methyl-1-pentene, 3-methyl-1-pentene and 1-decene. 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosane and the like.

  The propylene-based copolymer resin may be polymerized using a multi-site catalyst, a single-site catalyst, or any other catalyst. Further, a propylene-based copolymer in which the crystal / amorphous structure (morphology) of the polymer is controlled in nano order can be used.

  The ethylene copolymer resin may be polymerized with any of a multisite catalyst, a single site catalyst, and other catalysts. Further, an ethylene copolymer in which the crystal / amorphous structure (morphology) of the polymer is controlled in nano order can be used.

When a polyethylene resin is used as the material for the inner layer, the density of the polyethylene resin is preferably 0.860 to 0.920 g / cm ³ from the viewpoint of obtaining an appropriate cushioning property, and 0.870 to 0.915 g. / Cm ³ is more preferable, and 0.870 to 0.910 g / cm ³ is still more preferable. When a resin layer having a density of 0.920 g / cm ³ or more is formed as a layer (inner layer) that does not contact the object to be sealed, the transparency tends to deteriorate.

  Moreover, the resin sealing sheet may have a structure in which one or two or more layers of the same component are laminated on both surfaces of the center layer so as to be symmetrically arranged with respect to the center layer. As such a resin sealing sheet, for example, a resin sealing sheet composed of two surface layers (hereinafter sometimes referred to as “skin layer”) and three inner layers, Examples thereof include a resin-encapsulated sheet in which the surface layer is composed of the same component, and two inner layers adjacent to the surface layer (hereinafter sometimes referred to as “base layer”) are composed of the same component.

  In the resin sealing sheet having the above structure, the film thickness of the surface layer is preferably 5 to 40% with respect to the film thickness of the entire resin sealing sheet, and the film thickness of the base layer is the resin sealing sheet. The film thickness of the inner layer (hereinafter sometimes referred to as “core layer”) sandwiched between the base layers is preferably 50% to 90% with respect to the entire film pressure. It is preferable that it is 5 to 40% with respect to the film thickness.

  Next, the viewpoint of resin-encapsulated sheet processability is examined. The MFR (190 ° C., 2.16 kg) of the resin constituting the resin sealing sheet is preferably 0.5 to 30 g / 10 min from the viewpoint of ensuring good workability, and 0.8 to 30 g / 10 min. It is more preferable that it is 1.0 to 25 g / 10 min. When the resin sealing sheet has a multilayer structure of two or more layers, the MFR of the resin constituting the inner layer (base layer or core layer) is preferably lower than the MFR of the surface layer from the viewpoint of resin sealing sheet processability.

  In the resin-encapsulated sheet in the present embodiment, various additives such as a coupling agent, an antifogging agent, a plasticizer, an antioxidant, a surfactant, a colorant, and an ultraviolet absorber are provided as long as the characteristics are not impaired. Further, an antistatic agent, a crystal nucleating agent, a lubricant, an antiblocking agent, an inorganic filler, a crosslinking regulator, and the like may be added.

  A coupling agent may be added to the resin sealing sheet for the purpose of ensuring stable adhesion. The addition amount and type of the coupling agent can be appropriately selected depending on the desired degree of adhesion and the type of adherend. The addition amount of the coupling agent is preferably 0.01 to 5% by mass, more preferably 0.03 to 4% by mass, based on the total mass of the resin layer to which the coupling agent is added. More preferably, the content is 0.05 to 3% by mass. As the kind of the coupling agent, a substance that gives the resin layer good adhesion to a solar battery cell or glass is preferable, and examples thereof include organic silane compounds, organic silane peroxides, and organic titanate compounds. . These coupling agents may be added by a known addition method such as injection and mixing into a resin in an extruder, mixing and introducing into an extruder hopper, masterbatching, mixing and adding. it can. However, when passing through an extruder, the function of the coupling agent may be hindered by heat, pressure, etc. in the extruder, so the amount of addition needs to be adjusted appropriately depending on the type of coupling agent. In addition, the type of the coupling agent may be appropriately selected in consideration of the transparency of the resin-encapsulated sheet and the degree of dispersion, the corrosion on the extruder, and the viewpoint of extrusion stability. Preferred coupling agents include γ-chloropropylmethoxysilane, vinyltrichlorosilane, vinyltriethoxysilane, vinyl-tris (β-methoxyethoxy) silane, γ-methacryloxypropyltrimethoxysilane, β- (3,4- Ethoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β- (aminoethyl) -γ- Examples thereof include those having an unsaturated group or an epoxy group such as aminopropyltrimethoxysilane glycidoxypropyltriethoxysilane.

  Moreover, an ultraviolet absorber, antioxidant, discoloration inhibitor, etc. can be added to a resin sealing sheet. In particular, when it is necessary to maintain transparency and adhesiveness over a long period of time, it is preferable to add an ultraviolet absorber, an antioxidant, a discoloration inhibitor and the like. When these additives are added to the resin, the amount added is preferably 10% by mass or less, more preferably 5% by mass or less, based on the total amount of the resin to be added.

  Examples of the ultraviolet absorber include 2-hydroxy-4-n-octoxybenzophenone, 2-hydroxy-4-n-5-sulfobenzophenone, 2-hydroxy-4-methoxybenzophenone, and 2,2′-dihydroxy-4. , 4′-dimethoxybenzophenone, 2-hydroxy-4-n-dodecyloxybenzophenone, 2,4-dihydroxybenzophenone, 2,2′-dihydroxy-4-methoxybenzophenone, and the like. Examples of the antioxidant include phenol-based, sulfur-based, phosphorus-based, amine-based, hindered phenol-based, hindered amine-based, and hydrazine-based antioxidants.

  These ultraviolet absorbers, antioxidants, discoloration inhibitors and the like are preferably added in an amount of 0 to 10% by mass, more preferably 0 to 5% by mass, in the resin constituting the resin sealing sheet. When added to an ethylene-based resin, adhesiveness can be further imparted by mixing a resin having a silanol group into a master batch. The addition method is not particularly limited, and examples thereof include a method of adding to a molten resin in a liquid state, directly kneading and adding to the target resin layer, and applying after sheeting.

  Next, the optical characteristics of the resin sealing sheet will be described. A haze value is used as an index of optical characteristics. When the haze value is 10.0% or less, the sealed object sealed with the resin sealing sheet can be confirmed in appearance, and at the same time, when the power generation element of the solar cell is sealed, a practically sufficient power generation efficiency Is preferable. From the above viewpoint, the haze value is preferably 9.5% or less, and more preferably 9.0% or less. Here, the haze value can be measured according to ASTM D-1003.

  The resin-encapsulated sheet preferably has a total light transmittance of 85% or more, more preferably 87% or more, and 88% or more in order to ensure practically sufficient power generation efficiency. Is more preferable. Here, the total light transmittance can be measured in accordance with ASTM D-1003.

  The resin sealing sheet preferably has a thickness of 50 to 1500 μm, more preferably 100 to 1000 μm, and still more preferably 150 to 800 μm. When the thickness is less than 50 μm, there is a tendency for problems in durability and strength from the viewpoint of structurally poor cushioning properties or workability. On the other hand, when the thickness exceeds 1500 μm, there is a tendency that a problem of reducing productivity and adhesion is caused.

[Method for producing resin-encapsulated sheet]
Although there is no restriction | limiting in particular as a manufacturing method of a resin sealing sheet, For example, the following methods are mentioned. First, the resin is melted by an extruder, the molten resin is extruded from a die, and rapidly cooled and solidified to obtain an original fabric. As the extruder, a T die, an annular die or the like is used. When the resin sealing sheet has a multilayer structure, an annular die is preferable.

  The surface of the original fabric may be embossed according to the final form of the resin sealing sheet. For example, when embossing treatment is performed on both sides, between the two heated embossing rolls, when performing single-sided embossing processing, the original fabric is passed between embossing rolls heated only on one side. Embossing treatment can be performed. When the resin sealing sheet has a multilayer structure, a multilayer T die method and a multilayer annular (circular) die method are suitable, and the multilayer structure may be formed by other known laminating methods.

  Further, as post-processing, for example, heat setting for dimensional stabilization, corona processing, plasma processing, lamination with other types of resin sealing sheets, and the like may be performed.

  Depending on each case, it is selected whether the crosslinking treatment for the resin constituting the resin encapsulating sheet, that is, the heat treatment by the use of ionizing radiation irradiation or the use of organic peroxide is performed as a pre-process or a post-process of the embossing process. be able to.

[Translucent insulating substrate]
There are no particular restrictions on the light-transmitting insulating substrate, but because it is located on the outermost layer of the solar cell module, long-term reliability in outdoor exposure of the solar cell module, including weather resistance, water repellency, contamination resistance, mechanical strength, etc. It is preferable to provide performance for ensuring the performance. Moreover, in order to utilize sunlight effectively, it is preferable that it is a highly transparent sheet | seat with a small optical loss.

  Examples of the material of the translucent insulating substrate include a resin film made of polyester resin, fluororesin, acrylic resin, cyclic olefin (co) polymer, ethylene-vinyl acetate copolymer, and a glass substrate. A glass substrate is preferable from the viewpoint of a balance between weather resistance, impact resistance, and cost.

  Particularly suitable as the resin film is a polyester resin excellent in transparency, strength, cost and the like, particularly a polyethylene terephthalate resin.

  A fluororesin having particularly good weather resistance is also preferably used. Specifically, tetrafluoroethylene-ethylene copolymer (ETFE), polyvinyl fluoride resin (PVF), polyvinylidene fluoride resin (PVDF), polytetrafluoroethylene resin (TFE), tetrafluoroethylene-6 Examples thereof include a fluorinated propylene copolymer (FEP) and a poly (trifluorotrifluoroethylene resin) (CTFE). A polyvinylidene fluoride resin is preferable from the viewpoint of weather resistance, but an ethylene tetrafluoride-ethylene copolymer is preferable from the viewpoint of achieving both weather resistance and mechanical strength. Moreover, it is preferable to perform a corona treatment and a plasma treatment to a translucent insulated substrate for the improvement of adhesiveness with the material which comprises other layers, such as a resin sealing sheet. Moreover, in order to improve mechanical strength, it is also possible to use a sheet that has been subjected to a stretching treatment, for example, a biaxially stretched polypropylene sheet.

  When a glass substrate is used as the translucent insulating substrate, the total light transmittance of light having a wavelength of 350 to 1400 nm is preferably 80% or more, and more preferably 90% or more. As such a glass substrate, it is common to use white plate glass with little absorption in the infrared part, but even blue plate glass has little influence on the output characteristics of the solar cell module if the thickness is 3 mm or less. Further, tempered glass can be obtained by heat treatment to increase the mechanical strength of the glass substrate, but float plate glass without heat treatment may be used. Further, an antireflection coating may be applied to the light receiving surface side of the glass substrate in order to suppress reflection.

[Back insulating substrate]
Although there is no restriction | limiting in particular as a back surface insulating substrate, Since it is located in the outermost layer of a solar cell module, various characteristics, such as a weather resistance and mechanical strength, are calculated | required similarly to the above-mentioned translucent insulating substrate. Therefore, you may comprise a back surface insulating board | substrate with the material similar to a translucent insulating board | substrate. That is, the above-described various materials that can be used in the light-transmitting insulating substrate can also be used in the back insulating substrate. In particular, a polyester resin and a glass substrate can be preferably used, and among these, a polyethylene terephthalate resin (PET) is more preferable from the viewpoint of weather resistance and cost.

  Since the back insulating substrate does not assume the passage of sunlight, the transparency (translucency) required for the light transmitting insulating substrate is not necessarily required. Therefore, a reinforcing plate may be attached to increase the mechanical strength of the solar cell module or to prevent distortion and warpage due to temperature change. For example, a steel plate, a plastic plate, an FRP (glass fiber reinforced plastic) plate or the like can be preferably used.

  Further, the back insulating substrate may have a multilayer structure composed of two or more layers. Examples of the multilayer structure include a structure in which one or more layers of the same component are laminated on both sides of the central layer so as to be symmetrically arranged with respect to the central layer. As what has such a structure, PET / alumina vapor deposition PET / PET, PVF (brand name: Tedlar) / PET / PVF, PET / AL foil / PET etc. are mentioned, for example.

[Solar cells]
The solar battery cell is not particularly limited as long as it can generate power using the photovoltaic effect of the semiconductor. For example, silicon (single crystal system, polycrystalline system, amorphous system), compound semiconductor (3 -5, 2-6, etc.) can be used, and among these, polycrystalline silicon is preferred from the viewpoint of balance between power generation performance and cost.

[Method for manufacturing solar cell module]
There is no restriction | limiting in particular as a manufacturing method of the solar cell module in this Embodiment, For example, it laminates | stacks in order of a translucent insulated substrate / resin sealing sheet / solar cell / resin sealing sheet / back surface insulating substrate, and vacuum lamination It can manufacture by vacuum-laminating on conditions of 150 degreeC and 15 minutes using an apparatus.

  The thickness of each member in the solar cell module is not particularly limited, but the thickness of the translucent insulating substrate is preferably 3 mm or more from the viewpoint of weather resistance and impact resistance, and the thickness of the back insulating substrate is insulating. From the viewpoint of safety, preferably 75 μm or more, the thickness of the solar battery cell is preferably 140 to 250 μm from the viewpoint of balance between power generation performance and cost, and the thickness of the resin sealing sheet is from the viewpoint of cushioning and sealing properties. Preferably it is 250 micrometers or more.

  Hereinafter, although a specific Example and a comparative example are given and demonstrated, this Embodiment is not limited only to these Examples. In Examples 1 to 4 and Comparative Examples 1 and 2, a resin-sealed sheet having a multilayer structure was produced by sandwiching a predetermined base layer between skin layers (surface layers).

The measuring method and evaluation method of each physical property in Examples and Comparative Examples are as follows.
<Gel fraction>
For the total layer gel fraction, the resin-encapsulated sheet was extracted for 12 hours in boiling p-xylene, and the proportion of the insoluble portion was determined by the following formula.
Gel fraction (mass%) = (sample weight after extraction / sample weight before extraction) × 100

<Power generation partial gap evaluation>
Glass plate for solar cell (white glass made by AGC, 5 cm × 10 cm square: 3 mm thick) / resin encapsulated sheet / power generation part (polycrystalline silicon cell) (thickness 250 μm) / resin encapsulated sheet / solar cell glass plate In this order, a solar cell module is manufactured by vacuum laminating at 150 ° C. for 15 minutes using an LM50 type vacuum laminator (NPC). The contact situation was confirmed visually.

As the evaluation of creep resistance, the following high temperature and high humidity test and temperature cycle test were conducted.
<High temperature and high humidity test>
6 inch polycrystalline cells are arranged in 6 pieces (2 rows x 3 pieces), AGC white plate glass (530 mm x 350 mm square: 3 mm thickness) / resin encapsulated sheet / power generation part (polycrystalline silicon cell (thickness 250 μm) ) / Resin sealing sheet / back sheet (PET 180 μm) in this order, and a LM50 type vacuum laminating apparatus (NPC) was used for vacuum lamination under conditions of 150 ° C. for 15 minutes to produce a solar cell module. The prepared module was placed in a test tank, and maintained at a test temperature of 85 ° C. and a relative humidity of 85%, and the appearance of the module after each time was checked.

<Temperature cycle test>
6 inch polycrystalline cells are arranged in 6 pieces (2 rows x 3 pieces), AGC white plate glass (530 mm x 350 mm square: 3 mm thickness) / resin encapsulated sheet / power generation part (polycrystalline silicon cell (thickness 250 μm) ) / Resin sealing sheet / back sheet (PET 180 μm) in this order, and a LM50 type vacuum laminating apparatus (NPC) was used for vacuum lamination under conditions of 150 ° C. for 15 minutes to produce a solar cell module. The prepared module is installed in the test chamber, the test chamber is closed, the air around the module is circulated at a speed of 2 m / s or more, and the temperature in the test chamber is periodically between −40 ° C. and + 85 ° C. The cycle was set to 4 hours, held at the minimum temperature and the maximum temperature for 30 minutes, and the temperature cycle was performed.The appearance of the module after a predetermined number of times such as 200 times was checked. .

<Confirmation of oil condition of vacuum pump>
The oil in the vacuum pump was withdrawn from the drain after 100 hours had elapsed since the addition of new oil, and the color of the oil was confirmed. The target for oil change was when the color turned brown.

<Irradiation treatment>
The resin-encapsulated sheet was processed with an electron beam by using an EPS-300 or EPS-800 electron beam irradiation apparatus (manufactured by Nisshin High Voltage) at various acceleration voltages and irradiation densities.

<MFR of ethylene polymer>
It measured based on JIS-K-7210.

The materials used in the examples and comparative examples are as follows.
<Resin sealing sheet>
(1) Ethylene-vinyl acetate copolymer (EVA)
EVA751 manufactured by Tosoh Corporation
(2) Saponified ethylene-vinyl acetate copolymer Tosoh Corporation Mersen 6410
<Organic peroxide>
Yoshitomi-made Rupar 101
<Translucent insulating substrate>
AGC glass for solar cells <Insulating substrate (back sheet)>
Mitsubishi Aluminum Packaging Back Sheet <Solar Cell>
Crystalline silicon cell manufactured by E-TON

Hereinafter, it shows about the manufacturing method of the resin sealing sheet of Examples 1-4 and Comparative Examples 1-2.
<Examples 1-4>
Using the resins shown in Table 1, two extruders (skin layer extruder, base layer extruder) were used to melt the resin, and the resin was melted into a tube from an annular die connected to the extruder. Extrusion and resin-encapsulated sheets of Examples 1 to 4 were obtained by rapidly cooling a tube formed by melt extrusion using a water-cooling ring. In introducing the organic peroxide, the resin to be introduced was kneaded in advance at a concentration of about 5% by mass to form a master batch, which was diluted to the desired amount. In the table, the thickness ratio indicates the ratio of the thickness of each layer when the thickness of the entire resin sealing sheet is 100.

For the resin sealing sheets of Examples 1 and 2, an organic peroxide was used as a crosslinking agent. The resin encapsulated sheets of Examples 3 and 4 were subjected to electron beam crosslinking treatment in accordance with “irradiation conditions” shown in Table 1. The gel fraction was evaluated about each obtained resin sealing sheet.
Using the obtained resin-encapsulated sheet, a solar cell module was produced according to each condition shown in Table 1, and each evaluation test described above was performed. The evaluation results are shown in Table 1. In addition, as a vacuum laminator, the vacuum laminator LM50 for solar cells made from NPC was used.

<Comparative Examples 1 and 2>
Using the resins shown in Table 1, resin-encapsulated sheets were produced according to the respective conditions in the same manner as in the examples. The resin sealing sheet of Comparative Example 1 was subjected to crosslinking treatment using an organic peroxide as a crosslinking agent, and the resin sealing sheet of Comparative Example 2 was not subjected to crosslinking treatment. The gel fraction was evaluated about each obtained resin sealing sheet.
Using the obtained resin-encapsulated sheet, a solar cell module was produced according to each condition shown in Table 1, and each evaluation test described above was performed. The evaluation results are shown in Table 1. In addition, as a vacuum laminator, the vacuum laminator LM50 for solar cells made from NPC was used.

  As is clear from the results in Table 1, in the solar cell module of the present embodiment (Examples 1 to 4), only one of the two resin-encapsulated sheets adjacent to the solar cell is cross-linked. The vacuum pump of the vacuum laminator was less contaminated and excellent in the balance between creep resistance and gap filling properties.

  According to the present invention, it is possible to provide a solar cell module that can reduce contamination of a vacuum pump of a vacuum laminator and has an excellent balance of creep resistance and gap filling properties.

1: Solar cell module 2: Translucent insulating substrate 3: Back insulating substrate 4: Solar cell 5A: Resin encapsulating sheet 5B: Resin encapsulating sheet

Claims (4)

A solar cell module formed by sealing solar cells between a translucent insulating substrate and a back insulating substrate with a resin sealing sheet,
A solar cell module in which only one of the two resin-encapsulated sheets adjacent to the solar cell is crosslinked.   The solar cell module according to claim 1, wherein, of the two resin sealing sheets adjacent to the solar battery cell, only the resin sealing sheet on the back insulating substrate side is cross-linked.   The solar cell module according to claim 1, wherein the resin sealing sheet is subjected to a crosslinking treatment with ionizing radiation.   The resin-encapsulated sheet includes an ethylene-vinyl acetate copolymer, an ethylene-aliphatic unsaturated carboxylic acid copolymer, an ethylene-aliphatic carboxylic acid ester copolymer, an ethylene-vinyl acetate copolymer saponified product, an ethylene- The solar cell module of any one of Claims 1-3 containing the at least 1 sort (s) of resin selected from the group which consists of a vinyl acetate-acrylic acid ester copolymer saponified material and polyolefin resin.

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