JP2011119475A - Method of manufacturing solar cell module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a solar cell module with a high moisture vapor barrier property, excellent in corrosion resistance of a metal member such as a power generation element, and with a high creep resistance. <P>SOLUTION: In the method of manufacturing the solar cell module including the steps of sandwiching at least the power generation element (16) and sealing materials (18a, 18b) between a transparent base material (12) and a back sheet (14) for lamination, the sealing materials (18a, 18b) contain at least one of resin selected from a group consisting of an ethylene-aliphatic carboxylate ester copolymer, an ethylene copolymer containing glycidyl methacrylate, and a polyolefin resin. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for manufacturing 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 preheating step and a pressing step above the melting temperature of the resin (temperature condition of 150 ° C in the case of EVA) 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. Thereby, mutual adhesiveness improves more and the outstanding adhesiveness with glass, a power generation element, and a back sheet is implement | achieved.

  For example, Patent Document 1 discloses a solar cell module in which a light-transmitting substrate, a surface sealing material film, a photovoltaic element, a back surface sealing material film, and a back surface protection film are stacked. An encapsulant film is disclosed for an ethylene-vinyl acetate copolymer sheet.

JP 2002-134768 A

  However, the conventional solar cell module used for the sealing material such as EVA has a problem that the water vapor permeability of the sealing material is large and thus it is vulnerable to moisture. In particular, when the solar cell module is used in a humid environment, water vapor flows from the end of the solar cell module and adheres to the power generation part such as the power generation element, which corrodes metal members such as the power generation element. This can result in malfunction. This problem is remarkable in the case of a thin film solar cell module. On the other hand, it is also demanded that the power generation element has excellent sealing performance.

  The present invention has been made in view of the above circumstances, and provides a method for producing a solar cell module having high water vapor barrier properties, excellent corrosion resistance of metal members such as power generation elements, and excellent creep resistance. Is the main purpose.

  As a result of intensive studies to solve the above-mentioned problems, the inventors of the present invention have a process of sandwiching at least a power generation element and a sealing material between a transparent base material and a back sheet, and integrating them by lamination. A method for producing a solar cell module comprising at least one resin selected from the group consisting of an ethylene-aliphatic carboxylic acid ester copolymer, an ethylene copolymer containing glycidyl methacrylate, and a polyolefin resin. It has been found that the above problems can be solved by using a sealing material, and the present invention has been completed.

That is, the present invention is as follows.
[1]
A method for producing a solar cell module, comprising a step of sandwiching and laminating at least a power generation element and a sealing material between a transparent substrate and a backsheet,
The sealing material includes at least one resin selected from the group consisting of an ethylene-aliphatic carboxylic acid ester copolymer, an ethylene copolymer containing glycidyl methacrylate, and a polyolefin-based resin. Method.
[2]
The solar cell module according to [1], wherein the sealing material has a multilayer structure including two or more resin layers, and at least the resin layer on the transparent substrate side contains an adhesive resin. Production method.
[3]
[1] or [2], wherein the transparent substrate contains at least one selected from the group consisting of glass, polymethyl methacrylate (PMMA), polycarbonate (PC), and cyclic polyolefin (COP). Manufacturing method for solar cell module.
[4]
The manufacturing method of the solar cell module according to any one of [1] to [3], wherein the sealing material does not substantially contain an organic peroxide.
[5]
The method for producing a solar cell module according to any one of [1] to [4], further including a step of performing a crosslinking treatment on the sealing material by irradiation with ionizing radiation.
[6]
The method for manufacturing a solar cell module according to any one of [1] to [5], wherein an embossing process having a depth of 5 μm or more is performed on at least one surface of the sealing material.
[7]
The manufacturing method of the solar cell module according to any one of [1] to [6], wherein the sealing material contains a polyethylene resin having a density of 0.92 g / cm ³ or less.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the solar cell module which is high in water vapor | steam barrier property, excellent in the corrosion resistance of metal members, such as an electric power generation element, and excellent in sealing performance can be provided.

It is a schematic sectional drawing of one Embodiment of the solar cell module obtained by the manufacturing method of this Embodiment. It is a schematic top view which shows an example of the embossing shape given to a sealing material. FIG. 3 is a schematic sectional view taken along line A-A ′ of FIG. 2.

  Hereinafter, modes for carrying out the present invention (hereinafter simply referred to as “the present embodiment”) will be described. The following embodiments are exemplifications for explaining the present invention, and are not intended to limit the present invention to the following contents. And this invention can be deform | transformed suitably and implemented within the range of the summary.

(Method for manufacturing solar cell module)
The method for manufacturing a solar cell module according to the present embodiment includes a step of sandwiching at least a power generation element and a sealing material between a transparent base material and a back sheet and laminating and integrating the solar cell module. In the production method, the sealing material contains at least one resin selected from the group consisting of an ethylene-aliphatic carboxylic acid ester copolymer, an ethylene copolymer containing glycidyl methacrylate, and a polyolefin resin. To do.

(Transparent substrate)
The material of the transparent base material used for the manufacturing method of this Embodiment is not specifically limited, A well-known thing can be used. Here, the transparent substrate may be a substrate having at least light transmittance. In particular, from the viewpoint of ensuring long-term reliability during use of the solar cell module, a material having excellent mechanical strength such as weather resistance, water repellency, and impact resistance is preferable.

  Specific examples include a resin film made of a polyester resin, a fluororesin, an acrylic resin, a cyclic polyolefin, an ethylene-vinyl acetate copolymer, a glass substrate, and the like. Among these, a glass substrate, polymethyl methacrylate (PMMA), and cyclic polyolefin (COP) are preferable from the viewpoints of light transmittance, weather resistance, impact resistance, and cost balance.

  In particular, a fluororesin having excellent 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). Polyvinylidene fluoride resin is preferable from the viewpoint of weather resistance, but tetrafluoroethylene-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 transparent base material for the improvement of adhesiveness with the material which comprises other layers, such as a resin sealing material. 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 transparent substrate, the total light transmittance of light having a wavelength of 350 to 1400 nm is preferably 80% or more, 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 sheet)
The backsheet used in the production method of the present embodiment is not particularly limited, and is located on the outermost layer of the solar cell module, and thus has various properties such as weather resistance and mechanical strength, similar to the above-described translucent insulating substrate. Is required. Therefore, you may comprise a back sheet | seat with the material similar to a translucent insulated substrate. That is, the above-described various materials that can be used in the light-transmitting insulating substrate can also be used in the backsheet. 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 sheet does not assume the passage of sunlight, the transparency (light transmission) required for the transparent substrate is not necessarily required. Therefore, in order to increase the mechanical strength of the solar cell module or to prevent distortion and warpage due to temperature change, a reinforcing plate may be attached. For example, a steel plate, a plastic plate, an FRP (glass fiber reinforced plastic) plate or the like can be preferably used.

  The backsheet 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.

(Power generation element)
The power generating element used in the manufacturing method of the present embodiment is not particularly limited as long as it can generate power using the photovoltaic effect of a semiconductor or the like. For example, silicon (single crystal system, polycrystalline system, amorphous ( Amorphous)), compound semiconductors (Group 3-5, Group 2-6, etc.) can be used, and among these, polycrystalline silicon is preferable from the viewpoint of balance between power generation performance and cost.

(Encapsulant)
The sealing material used in the manufacturing method of the present embodiment is an ethylene-aliphatic unsaturated carboxylic acid copolymer, ethylene, from the viewpoint of ensuring good transparency, flexibility, adhesion and handling properties of the adherend. -It contains at least one resin selected from the group consisting of an aliphatic carboxylic acid ester copolymer, an ethylene copolymer containing glycidyl methacrylate, and a polyolefin resin.

  Conventionally used sealing materials such as EVA have a problem that water vapor easily flows in due to high water vapor permeability and is weak against moisture. In EVA or the like, the side chain portion is easily decomposed and detached. Further, since the side chain portion tends to be an acidic group or a polar group, it tends to easily retain moisture. As a result, when it is set as the solar cell module using sealing materials, such as EVA, it becomes easy to cause a withstand voltage fall and insulation fall. On the other hand, in the present embodiment, an ethylene-aliphatic unsaturated carboxylic acid copolymer, an ethylene-aliphatic carboxylic acid ester copolymer, an ethylene copolymer containing glycidyl methacrylate, and a polyolefin resin are selected. Therefore, the polarity can be suppressed, and excellent insulating properties can be imparted to the solar cell module. And it is excellent in water vapor | steam barrier property, and can protect a power generating element reliably even under high temperature, high humidity. In particular, when a sealing material that has been subjected to a crosslinking treatment is used, these advantages become more remarkable.

  An 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. 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.

  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. MFR (190 ° C., 2.16 kg) is preferably 0.3 to 30 g / 10 minutes, more preferably 0.5 to 30 g / 10 minutes, and 0.8 to 25 g / 10 minutes. More preferably.

  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.

  The polyolefin resin is preferably a polyethylene resin, a polypropylene resin, or a polybutene resin from the viewpoint of a water vapor barrier or not containing acetic acid, and a polyethylene resin is preferable from the viewpoint of flexibility. 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.

The resin layer preferably contains a polyethylene resin having a density of 0.92 g / cm ³ or less. By using a polyethylene resin having a density of 0.92 g / cm ³ or less, the transparency can be greatly improved. The lower limit of the density is preferably 0.86 or more, and more preferably 0.87 or more, from the viewpoint of manufacturability of the polyethylene resin. Moreover, when using a high density polyethylene-type resin together, transparency can also be improved by adding a low density polyethylene-type resin in the ratio of about 30 mass%, for example.

Furthermore, it is more preferable to use linear low density polyethylene having a density of 0.92 g / cm ³ or less. By using linear low density polyethylene, the polarity can be further suppressed, and excellent insulating properties can be obtained. And it is excellent in water vapor | steam barrier property, and can seal a to-be-sealed object reliably under high temperature and high humidity. In particular, when the crosslinking treatment is performed, these advantages become more remarkable.

  The linear low density polyethylene preferably has an MFR (190 ° C., 2.16 kg) of 0.5 to 30 g / 10 minutes, from 0.8 to 30 g / 10 minutes, from the viewpoint of workability of the sealing material. More preferably, it is 1.0 to 25 g / 10 min.

  Linear low-density polyethylene can be polymerized using known catalysts such as single-site catalysts and multi-site catalysts, but the content of low-molecular components can be suppressed, and low-density resins can be efficiently used. From the viewpoint of synthesis, etc., it is preferable to perform polymerization using a single site catalyst. The single-site catalyst is not particularly limited, and a known one can be used. Examples thereof include metal complexes having a cyclopentacene ring, and commercially available products can also be used.

  It is preferable that the sealing material does not substantially contain an organic peroxide. The organic peroxide causes thermal decomposition or the like in a high temperature environment. However, since the sealing material does not substantially contain the organic peroxide, the temperature restriction at the time of manufacture can be relaxed. As a result, the film forming speed, the embossing speed, etc. can be improved, and the productivity is excellent. Examples of such organic peroxides include 1,1-bis (t-butylperoxy) 3,3,5-trimethylcyclohexane, 1,1-bis (t-butylperoxy) cyclohexane, and n-butyl. Examples include -4,4-bis (t-butylperoxy) valerate, 2,2-bis (t-butylperoxy) butane, and the like.

  Further, the resin layer of the sealing material is preferably subjected to a crosslinking treatment. Thereby, good heat resistance can be imparted to the sheet without performing a long-time heat curing step. The crosslinking treatment is more preferably performed by irradiating with ionizing radiation. In this embodiment, since it is not always necessary to use an organic peroxide for the crosslinking treatment, gas generation due to thermal decomposition of the organic peroxide is small, and corrosion damage such as a vacuum pump or oil contamination is suppressed. can do. In the present embodiment, “crosslinking treatment” refers to a resin layer in a state where the gel fraction is preferably 3% by mass or more as a result of physical or chemical crosslinking of the polymer constituting the resin.

  The gel fraction of the sealing material can be appropriately controlled by adjusting the irradiation intensity (acceleration voltage) and irradiation density of ionizing radiation. The irradiation intensity (acceleration voltage) indicates how deeply electrons can reach in the thickness direction of the sealing material, and the irradiation density indicates how many electrons are irradiated per unit area. Examples of crosslinking by irradiation with ionizing radiation include a method in which ionizing radiation such as α-rays, β-rays, γ-rays, neutron beams, and electron beams is irradiated to the sealing material to crosslink. 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 sealing material.

  The gel fraction is preferably 3% by mass to 70% by mass, more preferably 3% by mass to 60% by mass, and still more preferably 3% by mass to 50% by mass. By setting the gel fraction within the above range, it is possible to further improve the performance of sealing the level difference of the objects to be sealed such as solar cells and wiring (gap filling property), and to improve creep resistance. It can be demonstrated. In addition, even if it is a case where a sealing material has any structure of the single layer structure mentioned later or a multilayer structure, the said gel fraction is the average gel fraction (all layer gel fraction) of the whole sealing material. Means value

The gel fraction of the sealing material can be obtained by the following formula from the ratio of the insoluble portion after extracting the sealing material in boiling p-xylene for 12 hours.
Gel fraction (mass%) = (sample weight after extraction / sample weight before extraction) × 100

  The sealing material may further contain an ionizing radiation-disintegrating resin. Here, the ionizing radiation decay type resin refers to a resin having a property of decaying by irradiating with ionizing radiation such as α rays, β rays, γ rays, neutron rays, and electron beams.

  Examples of the ionizing radiation disintegrating resin include disintegrating resins in which a functional group is bonded to the α-position of the C—C bond of the main chain. Examples of the functional group include a halogen atom, a hydroxy group, a nitro group, an optionally substituted alkyl group, an optionally substituted alkoxy group, an optionally substituted amino group, and an optionally substituted group. Examples include at least one selected from the group consisting of a carboxyl group, an optionally substituted amide group, and an optionally substituted aryl group.

  Here, the alkyl group, alkoxy group, amino group, carboxyl group, amide group, and aryl group may be substituted with one or more substituents at substitutable positions. Examples of the substituent include a halogen atom (eg, fluorine atom, chlorine atom, bromine atom), an alkyl group having 1 to 6 carbon atoms (eg, methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl). Group, sec-butyl group, tert-butyl group, pentyl group, hexyl group), aryl group (for example, phenyl group, naphthyl group), aralkyl group (for example, benzyl group, phenethyl group), alkoxy group (for example, methoxy group) Ethoxy group) and the like.

  Specifically, the ionizing radiation decay type resin is selected from the group consisting of polypropylene, polyisobutylene, poly α-methylstyrene, tetrafluoroethylene, polymethyl methacrylate, polyacrylamide, polymethyl glycidyl methacrylate, and cellulose. There is at least one kind.

  Further, the encapsulating material may contain an ionizing radiation cross-linkable resin having both a crosslinkable portion and a disintegratable portion. Examples of such a resin include an ethylene copolymer containing glycidyl methacrylate, an ethylene copolymer containing polypropylene, an ethylene copolymer containing methyl methacrylate, an ethylene copolymer containing glycidyl methacrylate, and an ethylene copolymer containing isoprene rubber. , Ethylene copolymers containing butadiene rubber, ethylene copolymers containing styrene-butadiene copolymer rubber, and the like.

  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.

  Moreover, the sealing material of this Embodiment may have any structure of the single layer structure comprised from the resin layer of 1 layer, and the multilayer structure comprised from the resin layer of 2 layers or more. Hereinafter, each structure will be described. Here, when the sealing material has a multilayer structure, a layer in contact with an object to be sealed such as a power generation element is referred to as a “surface layer”, and the other layer is referred to as an “inner layer” (in the case of three or more layers). That is, the two layers forming both surfaces of the sealing material are “surface layers”.

[Single layer structure]
When the encapsulant has a single-layer structure, the encapsulant is an ethylene-aliphatic unsaturated carboxylic acid copolymer from the viewpoint of ensuring good transparency, flexibility, adhesion of the adherend and handling properties. , An ethylene-aliphatic unsaturated carboxylic acid ester copolymer, and a layer containing at least one resin selected from the group consisting of polyolefin resins.

  When the saponified ethylene-vinyl acetate copolymer and the saponified ethylene-vinyl acetate-acrylic acid ester copolymer are contained as the adhesive resin in the resin layer constituting the sealing material, the saponification degree 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]
When the sealing material has a multilayer structure, any one of the layers is selected from the group consisting of an ethylene-aliphatic unsaturated carboxylic acid copolymer, an ethylene-aliphatic unsaturated carboxylic acid ester copolymer, and a polyolefin resin. Any layer containing at least one resin may be used. In this case, the adhesive resin contains at least one of ethylene-vinyl acetate copolymer saponified product, ethylene-vinyl acetate-acrylic ester copolymer saponified product, and ethylene-glycidyl methacrylate copolymer saponified product. It is preferable that the resin layer to be formed is formed as a layer (at least one surface layer) in contact with the object to be sealed. 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. Although content of adhesive resin in a surface layer is not specifically limited, From an adhesive viewpoint, 5-50 mass% is preferable, 5-40 mass% is more preferable, 5-35 mass% is further more preferable.

  Moreover, when the sealing material has a multilayer structure, it is preferable that the ionizing radiation-disintegrating resin is contained in a layer (at least one surface layer) that comes into contact with an object to be sealed. When ionizing radiation-disintegrating resin is contained in a layer that comes into contact with the encapsulated material of the sealing material, the performance of sealing the gap between the power generation element and the wiring without gaps (gap filling property) tends to be good. It is in.

  When the ionizing radiation-disintegrating resin is contained in a layer (at least one of the surface layers) in contact with the object to be sealed, the content of the ionizing radiation-disintegrating resin in the layer in contact with the object to be sealed is Preferably, it is 5-80 mass%, More preferably, it is 7-70 mass%, More preferably, it is 8-60 mass%.

  When the layer in contact with the object to be sealed contains an ionizing radiation-disintegrating resin, the gel fraction of the layer (surface layer) in contact with the object to be sealed is preferably less than 3% by mass, more preferably 2% by mass. The content is 0.1% by mass or more, more preferably 1% by mass or less and 0.1% by mass or more. If the gel fraction of the layer in contact with the object to be sealed is less than 3% by mass, the gap filling property tends to be good, and if it is 0.1% by mass or more, the resin can be used even in a high temperature state such as summer. It tends to be stable without melting and the material to be sealed flowing.

In the case of multiple layers, the density of the surface layer in contact with the object to be sealed is preferably 0.88 g / cm ³ or more from the viewpoint of blocking, and the cushioning property and cushioning transparency of the resin used for the surface layer are preferable. From the viewpoint, it is preferably 0.925 g / cm ³ or less. It is also effective to reduce the surface contact area by a known embossing method as a method for preventing blocking. 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 sealing material 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, chlorinated ethylene polymer resins, polyamide resins, and the like. It includes those possessed and plant-derived raw materials. 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 0.925 g / cm ³ . From the viewpoint of transparency, 0.925 g / cm ³ or less is preferable, and from the viewpoint of manufacturability of the polyethylene resin, 0.860 g / cm ³ or more is preferable.

  Further, the sealing material may have a structure in which one or two or more layers of the same component are laminated on both surfaces of the central layer so as to be symmetrically arranged with respect to the central layer. As such a sealing material, for example, a sealing material comprising two surface layers (hereinafter sometimes referred to as “skin layer”) and three inner layers, two surface layers. Are made of the same component, and two inner layers adjacent to the surface layer (hereinafter sometimes referred to as “base layer”) include the same component.

  In the sealing material 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 sealing material, and the film thickness of the base layer is the film of the entire sealing material. The 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 thickness. 5 to 40% is preferable.

  Next, workability of the sealing material will be examined. The MFR (190 ° C., 2.16 kg) of the resin constituting the sealing material is preferably 0.5 to 30 g / 10 minutes from the viewpoint of ensuring good workability, and 0.8 to 30 g / 10. It is more preferable that it is minute, and it is still more preferable that it is 1.0-25g / 10min. When the sealing material 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 workability of the sealing material.

  Next, the optical characteristics of the sealing material 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 sealing material can be confirmed in appearance, and at the same time, when used as a sealing material for solar cells, practically sufficient power generation efficiency is obtained. Since it is obtained, it 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 sealing material 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 for the solar cell module. More preferably. Here, the total light transmittance can be measured in accordance with ASTM D-1003.

  In the sealing material, various additives such as anti-fogging agent, plasticizer, antioxidant, surfactant, coloring agent, ultraviolet absorber, antistatic agent, crystal nucleating agent, as long as the properties are not impaired. A lubricant, an antiblocking agent, an inorganic filler, a crosslinking regulator, and the like may be added.

  A coupling agent may be further added to the sealing material for the purpose of ensuring stable adhesiveness. 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 a kind of coupling agent, the substance which gives the resin layer favorable adhesiveness to a photovoltaic cell or glass is preferable, for example, an organic silane compound, an organic silane peroxide, an organic titanate compound, etc. are mentioned. 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.

  The type of the coupling agent may be appropriately selected in consideration of the transparency of the sealing material and the degree of dispersion, corrosion to 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.

  An ultraviolet absorber, an antioxidant, a discoloration preventing agent, and the like can be added to the sealing material. 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 sealing material. 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.

  The sealing material 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.

  It is preferable that at least one surface of the sealing material is embossed. Blocking can be prevented by embossing.

  The embossing method is not particularly limited, and a known method can also be used. For example, after forming a resin into a sheet shape, the resin sheet is cooled and solidified, and the cooled and solidified resin sheet is heated to be softened. After that, it can be embossed.

  Examples of the method for forming a resin into a sheet include a T-die method, a circular die method, and a calendar method. The T-die method is suitable for forming a resin film having high fluidity (high melt flow). The circular die method is excellent in that a resin having a relatively low melt flow can be formed. Among these, the T die method and the circular die method are preferable from the viewpoint of stably forming a multilayered sheet, and the circular die method is more preferable from the viewpoint of equipment cost.

  As an example of a specific film forming method, for example, first, a resin as a raw material of a sealing material, and other additives as necessary, a previously known mixing device such as a Henschel mixer, a ribbon blender, a tumbler blender, etc. Pre-mix with etc. Subsequently, after melt-kneading with a screw extruder such as a single-screw extruder or a twin-screw extruder, a kneader, or a mixer, the kneaded product is extruded into a sheet form from a T-die, a circular die, a calendar die, or the like. At this time, it may be single layer extrusion or laminated extrusion.

  Next, the melt extruded into the sheet is once cooled and solidified. Examples of the cooling method include a method of directly contacting a cooling medium such as cold air or cooling water, a method of contacting a roll or press machine cooled with a refrigerant, and a method of contacting a roll or press machine cooled with a refrigerant. , Which is preferable in terms of excellent film thickness control.

  Although there is no restriction | limiting in particular as temperature at the time of cooling solidification, It is preferable that it is below melting | fusing point-5 degreeC of resin used as a material of a sheet | seat, More preferably, it is room temperature-melting | fusing point-5 degreeC, More preferably, room temperature-melting | fusing point- 10 ° C. At this time, in order to suppress the shrinkage rate of the sheet, it is preferable to slowly cool (slow cooling) in order to relax the flow orientation during film formation. As a cooling method, a method of cooling by directly immersing in a coolant such as water may be used, but from the viewpoint of reducing the shrinkage of the sheet, a method of gradually cooling with a temperature-controlled roll or a method of gradually cooling with air cooling is preferable. Even when a refrigerant is used, a method of spraying a mist-like mist and gradually cooling it is preferable. Here, the “melting point” in the case where a plurality of resins are used as the material of the sheet, such as when the sheet has a multilayer structure, means the melting point of the resin component contained most in the resin constituting the sheet. The melting point of the resin can be measured using a differential scanning calorimeter.

  Next, after the cooled and solidified resin sheet is heated and softened, the sheet surface is embossed. Here, “softening” (hereinafter also referred to as “softening”) refers to a state in which an embossing roll can be pressed to form and is usually heated at a temperature about 10 ° C. higher than the melting point of the resin. To soften.

  It does not specifically limit as a heating method for softening a resin sheet, For example, infrared heating, a heating roll, hot air heating etc. are mentioned. Among these, infrared heating is excellent in that it can efficiently heat the sheet to the center and it is easy to add deep embossing. Moreover, a heating roll and hot air heating are advantageous at the point which can raise the temperature of the surface which embosses at a stretch, and can create an emboss shape, preventing the expansion | extension of a sheet | seat and suppressing a shrinkage | contraction rate. Examples of infrared heating include far infrared and near infrared, and an optimum infrared wavelength for achieving a desired temperature may be selected. The said heating method may be used independently or may use 2 or more types together.

  The heating temperature when the resin sheet is softened by heating is not particularly limited, but is preferably in the vicinity of the melting point of the resin to be used when embossing deep. When shallow embossing is added, it is preferably about 3 ° C. lower than the melting point. In order to suppress the shrinkage rate, it is important not to stretch the sheet in the machine flow direction when softening in order to reduce the residual stress, but if the heating temperature is higher than the melting point + 20 ° C., Tends to be stretched in the machine flow direction. Accordingly, the heating temperature at the time of softening is preferably from melting point -5 ° C to melting point + 20 ° C, more preferably from melting point -3 ° C to melting point + 20 ° C.

  Further, as a heating method, first, after pre-heating by being in close contact with a heating roll or the like, the main heating may be performed by infrared heating or the like. After preheating, the main heating at a higher temperature has the advantage that a softened state that can sufficiently shape embossing can be achieved quickly. If it is not preheated, the temperature does not rise easily, so that shaping may be difficult, or the temperature may not be uniform and may become uneven. In addition, preheating has an advantage of preventing the sheet from being stretched and the shrinkage rate from being increased because the viscosity of the sheet does not drop extremely. As a heating method, after preheating with a heating roll having a temperature relatively lower than the melting point, immediately before the embossing roll, the surface is softened by heating with hot air or a specific infrared wavelength, and embossing is performed by pressing with an embossing roll. It is preferable to shape the shape. The preheating temperature is preferably a melting point of the resin from −20 ° C. to a melting point, more preferably from a melting point of −20 ° C. to a melting point of −3 ° C.

  It is preferable that the preheating roll has a non-adhesive surface because it tends not to stretch when the softened sheet is peeled off and tends to have a low shrinkage rate. Non-adhesive processing can be performed by fluorine-based, silicon-based or glass-based coating or surface coating.

  A shorter length of the preheating roll and the embossing roll is preferable because the shrinkage rate of the sheet tends to be reduced. Furthermore, when a softened sheet is peeled off from the preheating roll, a thin rotating roll (separating roll) is installed so that the sheet can be peeled off from the preheating roll without stretching the sheet, so that the shrinkage rate is further reduced. There is a tendency. At this time, it is preferable that the separating roll is also non-adhesive processed like the preheating roll.

  The surface of the resin sheet softened by heating is embossed according to the final form of the sealing material. For example, when embossing treatment is performed on both sides, at least one pair of two embossing rolls is used. When embossing treatment is performed on one surface, at least one pair of embossing rolls and backup rolls are used. By passing the formed resin sheet in a pressurized state, the shape of the embossing roll can be transferred to the sheet surface.

  The shape and size of the embossed portion of the embossed part are not particularly limited, and suitable conditions can be selected based on the use of the sealing material. There are no particular restrictions on the shape (pattern) of the embossing. Cup pattern) and the like. The embossed portion preferably has a small number of flat portions, and the ratio of the area of the convex portion due to embossing in the entire area of the embossed portion is more preferably 5 to 50%.

  FIG. 2 is a schematic top view showing an example of a sealing material having an embossed shape, and FIG. 3 is a schematic cross-sectional view taken along the line A-A ′ of FIG. 2. The emboss shape shown in FIGS. 2 and 3 is a quadrangular pyramid shape (so-called pyramid shape), and the depth of the emboss shape is D1 (see FIG. 3). When the surface of the solar cell encapsulating sheet has a square pyramid-shaped embossed shape, the solar cell encapsulating sheet abuts against an object to be encapsulated (for example, a power generation element or the like) at the apex of the quadrangular pyramid to seal.

  The embossing may be performed on at least a part of one surface of the sealing material, but the embossing may be performed on both surfaces of the sealing material. From the viewpoint of blocking resistance of the sealing material, the embossing depth is preferably 5 μm or more, more preferably 10 μm or more, and further preferably 50 μm or more. Here, the emboss depth refers to the depth from the embossed convex portion to the concave portion.

  Before and after the step of heating and softening the cooled and solidified resin sheet, tension control may be performed so that the softened resin sheet does not stretch. By performing tension control, stretching of the softened sheet is suppressed, and a lower shrinkage tends to be achieved. The tension at the time of tension control is 0.1 to 80N, more preferably 0.1 to 70N, and still more preferably 0.1 to 60N with respect to a sheet width of 1 m.

  As a tension control method, for example, before and after the process of heating and softening the cooled and solidified resin sheet, it is restrained by pinching with at least one pair of pinch rolls, at least one pair of backup rolls and embossing rolls. And the like.

  Furthermore, the sealing material that has been embossed may be subjected to, for example, heat setting for dimensional stabilization, corona treatment, plasma treatment, or lamination with other types of sealing materials. .

  Moreover, it can select whether the crosslinking process (irradiation of ionizing radiation etc.) with respect to a resin layer is performed as a pre-process or a post-process of an embossing process according to each case.

(laminate)
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 transparent base material / first sealing material / power generation element / second sealing material / back sheet, and vacuum lamination A solar cell module can be manufactured by vacuum laminating using an apparatus or the like.

  The lamination conditions are not particularly limited, and the lamination can be performed under the usual conditions. For example, the laminating condition is usually performed at 150 ° C., and the time is performed in two stages of a vacuum state time and a pressing time. The fast one has a vacuum state time of 5 minutes and a press time of 10 minutes at 150 ° C., and the slow one has a vacuum state time of 10 minutes and a press time of 20 minutes. Each temperature and each time can be appropriately changed in consideration of productivity, the type of member and productivity.

(Solar cell module)
FIG. 1 is a schematic cross-sectional view of one embodiment of a solar cell module obtained by the manufacturing method of the present embodiment. In the solar cell module 1 obtained in the present embodiment, the power generating element 16 is sandwiched between two or more sealing materials 18a and 18b, and the light receiving surface side is laminated with the transparent base material 12 and the back surface side is laminated with the back sheet 14. Have a structure. That is, it has a configuration of transparent base material 12 / sealing material 18a / power generation element 16 / sealing material 18b / back sheet 14. 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 configuration, and layers other than those described above are appropriately provided as long as the object of the present invention is not impaired. Or can be deformed. 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 further provided, but are not limited thereto. The positions where these layers are provided are not particularly limited, and can be provided at appropriate positions in consideration of the purpose of providing the layers and the characteristics of such layers.

  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 material is from the viewpoint of cushioning and sealing properties. Preferably it is 250 micrometers or more.

  The solar cell module obtained by the manufacturing method of the present embodiment has a high water vapor barrier property, can be used as a solar cell module excellent in corrosion resistance of a metal member such as a power generation element, and excellent in creep resistance.

  The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the following examples. The materials used in the examples and comparative examples are as follows.

<Resin>
(1) Ethylene-vinyl acetate copolymer (EVA)
2805 made by ARUKEMA
(2) Ethylene-vinyl acetate-glycidyl methacrylate copolymer (EVA-GMA copolymer)
Bond First 7B manufactured by Sumitomo Chemical Co., Ltd.
(3) Linear very low density polyethylene (VL)
EG8100 manufactured by Dow Chemical Company
EG8200 manufactured by Dow Chemical Company
1140G manufactured by Dow Chemical
(4) Linear low density polyethylene (LL)
FZ201 manufactured by Sumitomo Chemical Co., Ltd.
Asahi Kasei F1920

<Transparent substrate>
(1) Glass manufactured by AGC, glass for solar cells, white glass with a thickness of 3.2 mm with embossing
(2) Cyclic polyolefin (COP)
Made by Nippon Zeon Co., Ltd., Appel thickness 3mm
(3) Polycarbonate (PC)
Made by AGC, polycarbonate 3mm thick

<Back sheet>
Mitsubishi Aluminum Packaging Back Sheet Polyvinyl Fluoride (Trade Name: Tedlar) / PET / Polyvinyl Fluoride Back Sheet

<Power generation element>
E-TON, crystalline silicon cell thickness 250μm

<Irradiation treatment>

<Gel fraction>
Regarding the gel fraction, a sample 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
In the case of multiple layers, a sheet having the same thickness and the same resin composition was collected in advance by the same method, and the sheet irradiated under the same conditions was used as a gel fraction measurement sample.

<Polymer density>
It measured based on JIS-K-7112.

<MFR (melt flow rate) of polymer>
It measured based on JIS-K-7210.

<Preparation of resin encapsulated sheet>
First, it shows about the manufacturing method of the sealing material of each Example. Resin encapsulated sheets were produced with the materials and composition ratios (units are parts by mass) shown in each table. Using three extruders (surface layer extruder, inner layer extruder, surface layer extruder), the resin is melted, and the resin is melt extruded into a tube from a circular die connected to the extruder. The formed tube was formed into a film by an upward direct inflation method, and the molten resin sheet was cooled and solidified using cold air at 20 ° C. to obtain a resin sheet. Next, the cooled and solidified resin sheet was preheated by being in close contact with a preheating roll set at 50 ° C., and further softened by main heating with an infrared heater whose sheet temperature was set at 70 ° C. Next, embossing was performed by passing the softened resin sheet between a backup roll and an embossing roll. Here, the embossing of the pyramid pattern (quadrangular pyramid shape) shown in FIG.2 and FIG.3 was given, and the resin sealing sheet (embossing sheet) to which the embossing was given was obtained. Before and after the step of heating and softening the resin sheet, tension control was performed by a pair of pinch rolls, a pair of backup rolls and an embossing roll so that the softened resin sheet was not stretched. In the table, the thickness ratio of the surface layer / inner layer / surface layer indicates the ratio of the thickness of each layer when the thickness of the entire resin sealing sheet is 100. Using the EPS-300 or EPS-800 electron beam irradiation apparatus (manufactured by Nissin High Voltage), the obtained resin-encapsulated sheet (embossed sheet) is an electron beam at the acceleration voltage and irradiation density shown in each table. Processed.

<Production of solar cell module>
Using the obtained resin sealing sheet, a solar cell module was produced using the materials shown in Table 1. 6-inch polycrystalline cells are arranged in 6 sheets (2 rows x 3 sheets), transparent substrate (transparent protective material) / resin sealing sheet (a) / power generation element (250 μm) / resin sealing sheet (b) / back Sheets (back surface protective materials) were stacked in this order, and a solar cell module was manufactured by vacuum lamination under the conditions described in Table 1 using an LM50 type vacuum laminator (NPC), and each evaluation test was performed. The evaluation results are shown in Tables 1 to 4.

<Appearance after lamination>
The appearance immediately after lamination of the produced solar cell module was visually observed.
Then, the solar cell module was installed vertically in a test tank maintained at a test temperature of 85 ° C. and a relative humidity of 85%, and the appearance of the solar cell module after two weeks was visually observed. Those in which the displacement of the members such as the power generation elements were observed were judged as abnormal appearance, and those in which the displacement of the members such as the power generation elements were not observed were judged as good appearance.

<Water vapor transmission rate of sealing material (WVTR)>
It measured based on JIS-K7129.

<Discoloration test of copper plate>
In each example, a copper sheet (250 μm) was laminated under the same conditions in place of the power generation element to obtain a laminate sheet. This laminate sheet was placed vertically in a test tank maintained at a test temperature of 85 ° C. and a relative humidity of 85%, and the presence or absence of discoloration of the copper plate after 2 weeks was observed. Those in which rust and discoloration due to moisture were confirmed were judged as corrosion levels (discoloration), and those in which rust and discoloration were not confirmed were judged good.

  Tables 1 to 4 show the manufacturing conditions and physical property evaluation results of the examples and comparative examples.

  As shown in each table, the solar cell module of each example has high water vapor barrier properties, excellent corrosion resistance of metal members such as power generation elements, and excellent creep resistance, and excellent sealing performance. It was confirmed that

  The solar cell module obtained by the method for manufacturing a solar cell module according to the present invention is used as a solar cell module having a high water vapor barrier property, excellent corrosion resistance of a metal member such as a power generation element, and excellent creep resistance. Can do.

DESCRIPTION OF SYMBOLS 1 Solar cell module 12 Transparent base material 14 Back sheet 16 Electric power generation element 18a, 18b Sealing material

Claims (7)

A method for producing a solar cell module, comprising a step of sandwiching and laminating at least a power generation element and a sealing material between a transparent substrate and a backsheet,
The sealing material includes at least one resin selected from the group consisting of an ethylene-aliphatic carboxylic acid ester copolymer, an ethylene copolymer containing glycidyl methacrylate, and a polyolefin-based resin. Method.   The solar cell module according to claim 1, wherein the sealing material has a multilayer structure including two or more resin layers, and at least the resin layer on the transparent substrate side contains an adhesive resin. Production method.   The sun according to claim 1 or 2, wherein the transparent substrate contains at least one selected from the group consisting of glass, polymethyl methacrylate (PMMA), polycarbonate (PC), and cyclic polyolefin (COP). Manufacturing method of battery module.   The manufacturing method of the solar cell module as described in any one of Claims 1-3 with which the said sealing material does not contain an organic peroxide substantially.   The manufacturing method of the solar cell module as described in any one of Claims 1-4 which further includes the process of performing a bridge | crosslinking process to the said sealing material by irradiation with ionizing radiation.   The manufacturing method of the solar cell module as described in any one of Claims 1-5 by which the embossing of depth 5micrometer or more was given to the at least one surface of the said sealing material. The manufacturing method of the solar cell module as described in any one of Claims 1-6 in which the said sealing material contains the polyethylene-type resin with a density of 0.92 g / cm < ³ > or less.

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