WO2023238844A1 - Resin film for current collector sheets, film for current collector sheets, current collector sheet, solar cell element with current collector sheet, and solar cell - Google Patents

Resin film for current collector sheets, film for current collector sheets, current collector sheet, solar cell element with current collector sheet, and solar cell Download PDF

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Publication number
WO2023238844A1
WO2023238844A1 PCT/JP2023/020931 JP2023020931W WO2023238844A1 WO 2023238844 A1 WO2023238844 A1 WO 2023238844A1 JP 2023020931 W JP2023020931 W JP 2023020931W WO 2023238844 A1 WO2023238844 A1 WO 2023238844A1
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WIPO (PCT)
Prior art keywords
current collector
solar cell
collector sheet
layer
film
Prior art date
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PCT/JP2023/020931
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French (fr)
Japanese (ja)
Inventor
裕司 松本
慶太 在原
敦 中原
泰樹 高山
Original Assignee
大日本印刷株式会社
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Priority claimed from JP2022091429A external-priority patent/JP2023178632A/en
Priority claimed from JP2022091430A external-priority patent/JP2023178633A/en
Application filed by 大日本印刷株式会社 filed Critical 大日本印刷株式会社
Publication of WO2023238844A1 publication Critical patent/WO2023238844A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • B32B7/02—Physical, chemical or physicochemical properties
    • B32B7/027—Thermal properties
    • B32B7/028—Heat-shrinkability
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
    • H01L31/042—PV modules or arrays of single PV cells
    • H01L31/05—Electrical interconnection means between PV cells inside the PV module, e.g. series connection of PV cells

Definitions

  • the present disclosure relates to a resin film for a current collector sheet, a film for a current collector sheet, a current collector sheet, a solar cell element with a current collector sheet, and a solar cell.
  • a solar cell is used, for example, in the form of a module in which a plurality of solar cell elements are connected.
  • a method for connecting solar cell elements to each other for example, a method of connecting solar cell elements to each other using a strip-shaped conducting wire with a width of about 2 mm to 5 mm, called a buspar, has been used.
  • the problem is that sunlight is physically blocked in the area where the buspars are placed in the solar cell module, reducing the amount of sunlight incident on the solar electronic elements. be.
  • a method called multi-wire connection in which solar cell elements are connected to each other using wires (thin conductive wires) with a diameter of about 150 ⁇ m or more and 300 ⁇ m or less, for example.
  • a method for fixing the wires to the solar cell element is, for example, by embedding the wires in a thermofusible resin film to make a current collecting sheet, and then thermocompression bonding the current collecting sheet to the solar cell element. Examples include fixing methods (Patent Documents 1 and 2).
  • the resin film used for the current collector sheet is also called a connecting film.
  • Patent Document 3 in a current collecting wire fixing film for a solar cell module having a base material layer and a wire holding layer, the entire wire is fixed by optimizing the complex viscosity of the wire holding layer to a specific range.
  • a technique has been disclosed that can exert a suitable wire holding force while avoiding poor conduction due to being buried in the layer.
  • the adhesion of the resin film to the wire may not be sufficient, and there is still room for improvement.
  • the first object of the present invention is to provide a current collector sheet, a solar cell element with a current collector sheet, and a solar cell.
  • each member constituting the solar cell is required to have durability that can withstand the harsh outdoor environment for a long period of time.
  • the back protection sheet is required to have high weather resistance, and is also required to have high water vapor barrier properties in order to protect the solar cell element from moisture and the like.
  • Patent Document 4 a back protection sheet in which metal foil such as aluminum foil is laminated on a weather-resistant base material is known.
  • Patent Document 4 a back protection sheet in which metal foil such as aluminum foil is laminated on a weather-resistant base material.
  • a back protection sheet having metal foil is used in a solar cell module, there is a risk of electrical leakage due to its low insulation properties.
  • insulation treatment is performed on the end surfaces of metal foils, productivity decreases and manufacturing costs increase.
  • a back protection sheet there is also known a back protection sheet having a barrier film in which an inorganic vapor-deposited film is formed on a resin film instead of a metal foil.
  • a back protection sheet can exhibit water vapor barrier properties without using metal foil.
  • gas barrier films with high water vapor barrier properties comparable to metal foils are very expensive.
  • One embodiment of the present disclosure is a resin film for a current collector sheet used for a current collector sheet of a solar cell, which includes a base material layer, an adhesive layer, and a polyethylene resin layer in this order,
  • the layer contains a polyethylene terephthalate resin, the melt mass flow rate (MFR) at 190°C of the polyethylene resin layer is 4 g/10 minutes or more and 8 g/10 minutes or less, and heat shrinkage when held at 150° C. for 10 minutes.
  • MFR melt mass flow rate
  • a resin film for a current collector sheet having a ratio of 2.0% or less.
  • Another embodiment of the present disclosure is a film for a current collector sheet used for a current collector sheet of a solar cell, which includes a transparent base material, a transparent barrier layer, an adhesive layer, and a sealing layer in this order. , provides a film for current collector sheets.
  • Another embodiment of the present disclosure is a current collector sheet used for a solar cell, which includes the above resin film for current collector sheet and the polyethylene resin layer disposed on the surface side of the polyethylene resin layer of the resin film for current collector sheet.
  • a current collecting sheet having a wire is provided.
  • Another embodiment of the present disclosure is a current collector sheet used for a solar cell, which includes the above-mentioned current collector sheet film and a wire disposed on the surface side of the sealing layer of the current collector sheet film.
  • a current collector sheet having the following.
  • Another embodiment of the present disclosure is a current collector comprising the above-described current collector sheet and a solar cell element disposed on the surface side of the polyethylene resin layer of the current collector sheet and electrically connected to the wire.
  • a solar cell element with a sheet is provided.
  • Another embodiment of the present disclosure is a current collector comprising the above-described current collector sheet and a solar cell element disposed on the surface side of the sealing layer of the current collector sheet and electrically connected to the wire.
  • a solar cell element with a sheet is provided.
  • Another embodiment of the present disclosure provides a solar cell having a transparent substrate, a first encapsulant, the above-described solar cell element with a current collector sheet, a second encapsulant, and a counter substrate in this order. provide.
  • Another embodiment of the present disclosure provides a solar cell including, in this order, a transparent substrate, a first encapsulant, the above-described solar cell element with a current collector sheet, a second encapsulant, and a back protection sheet. I will provide a.
  • the resin film for a current collector sheet according to an embodiment of the present disclosure has excellent adhesion to wires, excellent wire embedding properties, and excellent thermal dimensional stability.
  • embodiments of the present disclosure can provide a film for current collector sheet having high barrier properties.
  • FIG. 1 is a schematic cross-sectional view illustrating a resin film for a current collector sheet in the present disclosure.
  • FIG. 1 is a schematic plan view and a cross-sectional view illustrating a current collecting sheet according to the present disclosure.
  • FIG. 1 is a schematic perspective view and a cross-sectional view illustrating a solar cell element with a current collector sheet according to the present disclosure.
  • FIG. 1 is a schematic cross-sectional view illustrating a film for a current collector sheet according to the present disclosure.
  • FIG. 1 is a schematic plan view and a cross-sectional view illustrating a current collecting sheet according to the present disclosure.
  • FIG. 1 is a schematic perspective view and a cross-sectional view illustrating a solar cell element with a current collector sheet according to the present disclosure.
  • FIG. 1 is a schematic perspective view and a cross-sectional view illustrating a solar cell element with a current collector sheet according to the present disclosure.
  • FIG. 1 is a schematic cross-sectional view illustrating a film for a current collector sheet according to the present disclosure.
  • FIG. 1 is a schematic cross-sectional view illustrating a current collector sheet in the present disclosure.
  • FIG. 1 is a schematic cross-sectional view illustrating a solar cell element with a current collector sheet according to the present disclosure.
  • FIG. 1 is a schematic cross-sectional view illustrating a current collector sheet in the present disclosure.
  • FIG. 1 is a schematic cross-sectional view illustrating a solar cell according to the present disclosure.
  • the resin film for current collector sheet in the present disclosure is a resin film for current collector sheet used for a current collector sheet of a solar cell, and includes a base material layer, an adhesive layer, a polyethylene resin layer, in this order, the base layer contains a polyethylene terephthalate resin, the polyethylene resin layer has a melt mass flow rate (MFR) at 190°C of 4 g/10 minutes or more and 8 g/10 minutes or less, and 150°C The heat shrinkage rate when held for 10 minutes is 2.0% or less.
  • MFR melt mass flow rate
  • FIG. 1 is a schematic cross-sectional view illustrating a resin film for a current collector sheet according to the present disclosure.
  • the resin film 10 for current collector sheet has a base material layer 1 containing polyethylene terephthalate resin, an adhesive layer 2, and a polyethylene resin layer 3 in this order.
  • the melt mass flow rate (MFR) of the polyethylene resin layer 3 is within a predetermined range.
  • the heat shrinkage rate of the resin film 10 for current collector sheet when held at 150° C. for 10 minutes is below a predetermined value.
  • FIGS. 2(a) and 2(b) are a schematic plan view and a cross-sectional view illustrating a current collecting sheet having a resin film for a current collecting sheet according to the present disclosure.
  • FIG. 2(b) is a cross-sectional view taken along the line AA in FIG. 2(a).
  • the current collector sheet 20 includes a resin film 10 for a current collector sheet, and a wire 11 disposed on the surface side of the polyethylene resin layer 3 of the resin film 10 for a current collector sheet. and has. In this way, the resin film 10 for current collector sheet is used to support the wire 11.
  • FIG. 2(a) shows a schematic plan view of the current collecting sheet viewed from the polyethylene resin layer side of the resin film for current collecting sheet.
  • FIGS. 3(a) to 3(c) are a schematic perspective view and a cross-sectional view illustrating a solar cell element with a current collecting sheet including a current collecting sheet having a resin film for a current collecting sheet according to the present disclosure.
  • FIG. 3(b) is a cross-sectional view taken along line AA in FIG. 3(a)
  • FIG. 3(c) is a cross-sectional view taken along line BB in FIG. 3(a). As shown in FIGS.
  • the solar cell element 30 with a current collector sheet is arranged on the surface side of the current collector sheet 20 and the polyethylene resin layer 3 of the current collector sheet 20, and is connected to the wire 11 and It has a solar cell element 31 which is connected to the solar cell element 31.
  • the resin film 10 for current collector sheet is used to fix the wire 11 electrically connected to the solar cell element 31.
  • the current collecting sheet 20 has two resin films 10 for current collecting sheets, and a solar cell element 31 is arranged on each resin film 10 for current collecting sheets. An example is shown.
  • the base layer contains polyethylene terephthalate resin.
  • the polyethylene terephthalate resin contained in the base material layer has a melting point of about 260° C. and has high heat resistance.
  • polyethylene terephthalate resin provides good rigidity when molded into a film. Therefore, the base material layer containing the polyethylene terephthalate resin can impart rigidity to the resin film for the current collector sheet. Therefore, when manufacturing a solar cell element with a current collector sheet using a current collector sheet having a resin film for the current collector sheet, the wire is sufficiently pressed against the solar cell element by the resin film for the current collector sheet during thermocompression bonding. be able to.
  • the MFR of the polyethylene resin layer is within a predetermined range, the adhesion of the polyethylene resin layer to the wire and the embeddability of the wire can be improved. Therefore, in the current collector sheet having the resin film for the current collector sheet, the wire can be well fixed to the solar electronic element by the resin film for the current collector sheet.
  • the wire when a solar cell element with a current collector sheet is used in a solar cell, the wire can be well fixed to the solar electronic element by the resin film for the current collector sheet, resulting in a decrease in power generation efficiency due to poor adhesion of the wire. can be suppressed.
  • the adhesion of the polyethylene resin layer to the solar cell element can also be improved.
  • the resin film for the current collector sheet can have rigidity because the base layer contains the polyethylene terephthalate resin. Therefore, thermal shrinkage of the resin film for current collector sheet can be suppressed. Furthermore, as described above, by setting the MFR of the polyethylene resin layer within a predetermined range, it is possible to improve the adhesion of the polyethylene resin layer to the wire, the embeddability of the wire, and the adhesion to the solar cell element. Therefore, even if the thickness of the polyethylene resin layer is relatively thin, adhesion to the wire, embeddability of the wire, and adhesion to the solar cell element can be ensured. When the thickness of the polyethylene resin layer is thin, the thermal shrinkage of the resin film for the current collector sheet becomes small.
  • the fact that the MFR of the polyethylene resin layer is within a predetermined range can also contribute to suppressing thermal shrinkage of the resin film for current collector sheet. Furthermore, since the resin film for a current collector sheet in the present disclosure has a predetermined thermal shrinkage rate, thermal dimensional stability can be improved. Therefore, when manufacturing a solar cell element with a current collecting sheet using a current collecting sheet having a resin film for current collecting sheet, it is possible to suppress the positional shift of the wire with respect to the solar cell element during the heating process. Moreover, when manufacturing a solar cell using a solar cell element with a current collector sheet, it is possible to suppress misalignment of the wire with respect to the solar cell element during the heating process. Furthermore, even if the solar cell reaches a high temperature in the environment in which the solar cell is used, it is possible to suppress misalignment of the wire relative to the solar cell element. Therefore, the reliability of the solar cell can be improved.
  • the resin film for a current collector sheet in the present disclosure has excellent thermal dimensional stability, it can be used when manufacturing a solar cell element with a current collector sheet using a current collector sheet having the resin film for a current collector sheet.
  • thermal shrinkage of the resin film for the current collector sheet during the heating process can be suppressed, and curl deformation can be suppressed.
  • the resin film for current collector sheet in the present disclosure has a base material layer, an adhesive layer, and a polyethylene resin layer in this order.
  • the polyethylene resin layer in the present disclosure is a member that supports the wire when the resin film for current collector sheet is used as the current collector sheet.
  • the melt mass flow rate (MFR) at 190°C of the polyethylene resin layer is preferably 4 g/10 minutes or more and 8 g/10 minutes or less, more preferably 6 g/10 minutes or more and 8 g/10 minutes or less. preferable.
  • MFR melt mass flow rate
  • the MFR of the polyethylene resin layer is within the above range, the adhesion to the wire and the embeddability of the wire can be improved.
  • the MFR of the polyethylene resin layer is 6 g/10 minutes or more, the polyethylene resin layer can have excellent adhesion to the wire and excellent wire embedding properties, regardless of the material of the wire.
  • the MFR of the polyethylene resin layer refers to the MFR of the polyethylene resin composition that constitutes the polyethylene resin layer.
  • the melt mass flow rate (MFR) of the polyethylene resin layer is measured in accordance with method A of JIS K7210-1:2014. The measurement conditions are a temperature of 190° C. and a load of 2.16 kg.
  • the MFR of the polyethylene resin layer can be adjusted by, for example, the molecular weight of the polyethylene resin contained in the polyethylene resin layer.
  • the melting point of the polyethylene resin layer is not particularly limited as long as it can exhibit desired thermal weldability.
  • the melting point of the polyethylene resin layer is, for example, preferably 100°C or higher and 120°C or lower, more preferably 105°C or higher and 110°C or lower. If the melting point of the polyethylene resin layer is too high, it is necessary to increase the heating temperature when press-bonding the current collector sheet to the solar cell element, which may increase manufacturing costs or cause the solar cell element to deteriorate. There is. On the other hand, if the melting point of the polyethylene resin layer is too low, the polyethylene resin layer may melt in the usage environment of the solar cell, making it difficult to fix the wire.
  • the melting point of the polyethylene resin layer is determined by differential scanning calorimetry (DSC) in accordance with JIS K7121:2012 (method for measuring transition temperature of plastics). In addition, in that case, when two or more melting point peaks exist, the higher temperature is taken as the melting point.
  • DSC differential scanning calorimetry
  • the polyethylene resin layer contains polyethylene resin.
  • the polyethylene resin is not particularly limited as long as it is possible to obtain a polyethylene resin layer that satisfies the above-mentioned MFR.
  • Examples of polyethylene resins include high-density polyethylene (HDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), metallocene-based linear low-density polyethylene (M-LLDPE), and ultra-low density polyethylene ( VLDPE), etc.
  • One type of polyethylene resin may be used alone, or two or more types may be used in combination. Among these, low density polyethylene (LDPE) is preferred because of its good flexibility and workability.
  • the density of the polyethylene resin is not particularly limited, and is preferably, for example, 0.890 g/cm 3 or more and 0.930 g/cm 3 or less, more preferably 0.900 g/cm 3 or more and 0.925 g/cm 3 or less.
  • the density of the polyethylene resin is within the above range, the flexibility and processability of the polyethylene resin layer can be improved, and the adhesion to the wire and the embeddability of the wire can be improved.
  • the density of the polyethylene resin is measured by a pycnometer method based on JIS K7112:1999.
  • the polyethylene resin layer may contain only polyethylene resin as a resin component, or may further contain a resin other than polyethylene resin in addition to polyethylene resin. In the latter case, the polyethylene resin layer preferably contains polyethylene resin as a main component. Note that the expression that the polyethylene resin layer contains polyethylene resin as a main component means that the proportion of polyethylene resin is the highest among all resin components.
  • the ratio of polyethylene resin to all resin components in the polyethylene resin layer is, for example, 50% by mass or more, may be 60% by mass or more, or may be 70% by mass or more. Further, the proportion of the polyethylene resin may be, for example, 99% by mass or less, 95% by mass or less, or 90% by mass or less. Note that the proportion of the polyethylene resin may be 100% by mass.
  • the polyethylene resin layer in the present disclosure may contain an adhesiveness improver.
  • the adhesion improver is a component that improves the adhesion to wires and the adhesion to solar cell elements.
  • adhesion improver examples include silane-modified resins, silane coupling agents, and the like.
  • silane-modified resin examples include silane-modified polyolefin resins.
  • the silane-modified polyolefin resin is a copolymer of an ⁇ -olefin and an ethylenically unsaturated silane compound.
  • the copolymer may be, for example, a random copolymer, an alternating copolymer, a block copolymer, or a graft copolymer.
  • the copolymer is preferably a graft copolymer, and is preferably a graft copolymer in which a main chain is a polyolefin and an ethylenically unsaturated silane compound is polymerized as a side chain.
  • a graft copolymer the degree of freedom of the silanol groups that contribute to adhesion is increased, so that the adhesion to the wire and the adhesion to the solar cell element can be further improved.
  • Examples of the ⁇ -olefin constituting the silane-modified polyolefin resin include ethylene, propylene, 1-butene, isobutylene, 1-pentene, 2-methyl-1-butene, 3-methyl-1-butene, 1-hexene, -heptene, 1-octene, 1-nonene, 1-decene, etc.
  • One type of ⁇ -olefin may be used alone, or two or more types may be used in combination.
  • polyethylene is preferred. That is, the silane-modified polyolefin resin is preferably a silane-modified polyethylene resin. This is because the silane-modified polyethylene resin has good compatibility with the polyethylene resin contained in the polyethylene resin layer.
  • the silane-modified polyethylene resin is preferably a resin obtained by graft-polymerizing linear low-density polyethylene (LLDPE) as the main chain with an ethylenically unsaturated silane compound as the side chain.
  • LLDPE linear low-density polyethylene
  • Examples of the ethylenically unsaturated silane compound include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltripropoxysilane, vinyltriisopropoxysilane, vinyltributoxysilane, vinyltripentyloxysilane, vinyltriphenoxysilane, vinyl Tribenzyloxysilane, vinyltrimethylenedioxysilane, vinyltriethylenedioxysilane, vinylpropionyloxysilane, vinyltriacetoxysilane, and vinyltricarboxysilane can be mentioned.
  • One type of ethylenically unsaturated silane compound may be used alone, or two or more types may be used in combination.
  • the silane-modified polyolefin resin can be obtained, for example, by the manufacturing method described in JP-A No. 2003-46105.
  • the silane-modified resins may be used alone or in combination of two or more.
  • the content of the silane-modified resin in the polyethylene resin layer is not particularly limited, and may be, for example, 25% by mass or less, or 15% by mass or less.
  • silane coupling agent As the silane coupling agent, a silane coupling agent used in general solar cell encapsulants can be used.
  • the silane coupling agents may be used alone or in combination of two or more.
  • the content of the silane coupling agent in the polyethylene resin layer is not particularly limited, and may be, for example, 5% by mass or less.
  • the polyethylene resin layer may contain additives such as an antioxidant, an anti-blocking agent, and a lubricant, if necessary.
  • the proportion of each resin component contained in each layer of the resin film for current collector sheet is detected by, for example, differential scanning calorimetry (DSC), infrared spectroscopy (IR), or nuclear magnetic resonance (NMR). Analyze based on peak ratio etc.
  • DSC differential scanning calorimetry
  • IR infrared spectroscopy
  • NMR nuclear magnetic resonance
  • the thickness of the polyethylene resin layer is not particularly limited as long as it can support the wire when the resin film for current collector sheet is used as the current collector sheet, and can be appropriately selected depending on the thickness of the wire.
  • the thickness of the polyethylene resin layer is preferably thicker than the thickness of the base material layer described below. Thereby, the adhesion to the wire and the embeddability of the wire can be improved.
  • the thickness of the polyethylene resin layer is preferably 40 ⁇ m or more and 100 ⁇ m or less, more preferably 45 ⁇ m or more and 80 ⁇ m or less. When the thickness of the polyethylene resin layer is within the above range, the adhesion to the wire and the embeddability of the wire can be improved.
  • the surface of the polyethylene resin layer opposite to the adhesive layer may be subjected to surface treatment. That is, the polyethylene resin layer may have a surface treatment portion on the opposite side to the adhesive layer. Thereby, the adhesion to the wire and the adhesion to the solar cell element can be improved.
  • the surface treatment is not particularly limited as long as it can improve adhesion to wires and solar cell elements, and examples include corona treatment, plasma treatment, ultraviolet treatment, electron beam treatment, flame treatment, etc. Can be mentioned. Among these, corona treatment is preferred from the viewpoint of processing cost and damage reduction to the polyethylene resin layer.
  • the base material layer in the present disclosure contains polyethylene terephthalate resin.
  • the base material layer is a member that provides rigidity to the resin film for current collector sheet.
  • the base material layer can contain various additives as necessary.
  • the thickness of the base layer is not particularly limited, and can be appropriately selected depending on the size and purpose of the solar cell in which the resin film for current collector sheet is used. As mentioned above, the thickness of the base material layer is preferably thinner than the thickness of the polyethylene resin layer. Specifically, the thickness of the base layer is preferably 12 ⁇ m or more and 38 ⁇ m or less, more preferably 12 ⁇ m or more and 25 ⁇ m or less. If the thickness of the base material layer is too thin, sufficient rigidity may not be obtained. Moreover, if the thickness of the base material layer is too thick, the rigidity will become too high, and there is a possibility that the followability of the resin film for the current collector sheet to the wire will decrease.
  • the base material layer is preferably subjected to an annealing treatment.
  • Thermal dimensional stability can be improved. This makes it easier to adjust the heat shrinkage rate of the resin film for current collector sheet, which will be described later, within a predetermined range. Therefore, when manufacturing a solar cell with a current collecting sheet using a current collecting sheet having a resin film for current collecting sheet, the position of the wire relative to the solar cell element during the heating process for fixing the wire to the solar cell element Misalignment can be suppressed.
  • the temperature of the annealing treatment of the base material layer is preferably, for example, 120° C. or more and 250° C. or less.
  • Adhesive Layer is a member that is disposed between the base layer and the polyethylene resin layer and serves to bond the base layer and the polyethylene resin layer.
  • the adhesive used for the adhesive layer is not particularly limited as long as it is transparent and capable of bonding the base material layer and the polyethylene resin layer, and general film adhesives can be used. Adhesives used for bonding can be mentioned. Examples of the adhesive include urethane adhesive, acrylic adhesive, polycarbonate adhesive, and phenol adhesive. Further, the adhesive may be, for example, an adhesive for dry lamination or an anchor coating agent for extrusion lamination.
  • the adhesive has heat and humidity resistance. Decrease in adhesive strength due to hydrolysis can be suppressed.
  • the resin component constituting the adhesive does not have an ester bond.
  • the main ingredient is a polycarbonate polyurethane resin.
  • the thickness of the adhesive layer is not particularly limited as long as it has transparency and can bond the base material layer and the polyethylene resin layer, and is preferably 0.1 ⁇ m or more and 10 ⁇ m or less, for example.
  • the thickness of the resin film for a current collector sheet in the present disclosure is not particularly limited, and can be appropriately selected depending on the thickness of the wire used in the current collector sheet.
  • the thickness of the resin film for the current collector sheet may be, for example, 50 ⁇ m or more and 300 ⁇ m or less. If the thickness of the resin film for current collector sheet is too thin, it may become difficult to fix the wire to the solar cell element. On the other hand, if the thickness of the resin film for the current collector sheet is too thick, the transparency may decrease.
  • the heat shrinkage rate when held at 150°C for 10 minutes is 2.0% or less, preferably 1.5% or less, and more preferably It is 1.0% or less.
  • thermal dimensional stability can be improved.
  • the wire is attached to the solar cell element during the heating process for fixing the wire to the solar cell element. Positional shift can be suppressed.
  • the melting points of these solders are relatively high.
  • the heating temperature in the heating process tends to be higher. Therefore, in the above case, the heat shrinkage rate of the resin film for current collector sheet is more preferably small, and specifically, 1.0% or less is more preferable.
  • the lower limit of the heat shrinkage rate may be 0% or more.
  • the heat shrinkage rate of the resin film for current collector sheet refers to the larger heat shrinkage rate of the heat shrinkage rate in the MD direction and the heat shrinkage rate in the TD direction. That is, in the resin film for a current collector sheet, the larger heat shrinkage rate of the heat shrinkage rate in the MD direction and the heat shrinkage rate in the TD direction falls within the above range.
  • the MD direction of the resin film for current collector sheet is usually the longitudinal direction of the resin film for current collector sheet.
  • the TD direction of the resin film for current collector sheet is usually the transverse direction of the resin film for current collector sheet.
  • thermal shrinkage rate of the resin film for the current collector sheet is measured, for example, by a method based on ASTM D1204.
  • Examples of methods for controlling the heat shrinkage rate of the resin film for current collector sheets include a method of adjusting the heat shrinkage rate of the base material layer.
  • methods for adjusting the heat shrinkage rate of the base material layer include, for example, a method of annealing the base material layer, a method of adjusting the crystallinity of the polyethylene terephthalate resin contained in the base material layer, and a method of adjusting the crystallinity of the polyethylene terephthalate resin contained in the base material layer.
  • Examples include a method of adjusting the molding method and molding conditions when molding the terephthalate resin into a film.
  • methods for adjusting the molding method include a method of performing a relaxation treatment to relieve stress and strain during molding.
  • examples of the molding conditions include the stretching ratio and the like.
  • Light transmittance at a wavelength of 400 nm or more and 1200 nm or less is such that sunlight can be transmitted through the solar cell element to the extent that it can generate electricity. There are no particular limitations.
  • the light transmittance of the resin film for current collector sheet at a wavelength of 400 nm or more and 1200 nm or less is preferably 75% or more, more preferably 80% or more, and even more preferably 85% or more. When the light transmittance is within the above range, the light utilization efficiency of the solar cell element can be increased.
  • the above light transmittance at a wavelength of 400 nm or more and 1200 nm or less is an average value of the light transmittance at a wavelength of 400 nm or more and 1200 nm or less.
  • the light transmittance at a wavelength of 400 nm or more and 1200 nm or less is measured in accordance with JIS K7361 1:1997. Specifically, the light transmittance at a wavelength of 400 nm or more and 1200 nm or less is measured using a haze meter HM150 manufactured by Murakami Color Research Institute.
  • the transparency of the resin film for a current collector sheet in the present disclosure is not particularly limited as long as it can transmit sunlight to the extent that the solar cell element can generate electricity.
  • the transparency of the resin film for current collector sheet can be evaluated by, for example, haze.
  • the haze of the resin film for the current collector sheet is, for example, 1% or more and 40% or less, may be 5% or more and 30% or less, or may be 10% or more and 20% or less.
  • haze is measured in accordance with JIS K7136:2000. Haze is measured using, for example, a haze meter HM150 manufactured by Murakami Color Research Institute.
  • a measurement sample is prepared and used for measurement.
  • the sample for measurement is prepared by the following method. First, a resin film for a current collector sheet is cut into a size of 50 mm x 50 mm to prepare a test piece. Next, the ETFE (tetrafluoroethylene-ethylene copolymer) film, the test piece, and the ETFE film were laminated in this order, and vacuum laminated at a set temperature of 165°C, vacuuming for 2 minutes, pressing for 2.5 minutes, and pressure of 100 kPa. I do. This is to eliminate minute irregularities on the surface of the resin film for current collector sheet at the film forming stage. Subsequently, the ETFE film is removed from both sides of the test piece to prepare a measurement sample.
  • ETFE tetrafluoroethylene-ethylene copolymer
  • Method for manufacturing a resin film for current collector sheet is particularly suitable if a resin film for current collector sheet having a base material layer, an adhesive layer, and a polyethylene resin layer in this order can be obtained.
  • a dry lamination method using a film-like base material layer and a polyethylene resin layer a method in which the base material layer and a polyethylene resin layer are laminated via a dry laminating adhesive, a method using a film-like base material layer, and an extrusion method.
  • the lamination method include a method in which a base material layer and a polyethylene resin layer are extruded and laminated via an anchor coating agent for lamination.
  • Examples of the method for forming the film-like base material layer and polyethylene resin layer include a method of preparing a resin composition for forming each layer and melt-molding the resin composition.
  • a known molding method can be used, and examples thereof include injection molding, extrusion molding, blow molding, compression molding, and rotational molding.
  • the temperature during molding is, for example, higher than the melting point of the resin composition. The upper limit of the temperature during molding is appropriately adjusted depending on the type of resin composition.
  • the film for current collector sheet in the present disclosure is a film for current collector sheet used for a current collector sheet of a solar cell, and includes a transparent base material, a transparent barrier layer, an adhesive layer, and a sealing layer. and, in this order.
  • FIG. 4 is a schematic cross-sectional view illustrating a film for a current collector sheet according to the present disclosure.
  • the current collector sheet film 50 includes a transparent base material 51, a transparent barrier layer 52, an adhesive layer 53, and a sealing layer 54 in this order.
  • the transparent base material 51 and the transparent barrier layer 52 constitute a barrier film 55.
  • FIGS. 5(a) and 5(b) are a schematic plan view and a cross-sectional view illustrating a current collecting sheet having a current collecting sheet film according to the present disclosure.
  • FIG. 5(b) is a cross-sectional view taken along line AA in FIG. 5(a).
  • the current collecting sheet 20 includes a current collecting sheet film 50 and a wire 11 disposed on the surface side of the sealing layer 54 of the current collecting sheet film 50. have In this way, the current collector sheet film 50 is used to support the wire 11.
  • FIG. 5(a) shows a schematic plan view of the current collecting sheet viewed from the sealing layer side of the film for current collecting sheet.
  • FIGS. 6(a) to 6(c) are a schematic perspective view and a cross-sectional view illustrating a solar cell element with a current collecting sheet including a current collecting sheet having a current collecting sheet film according to the present disclosure.
  • FIG. 6(b) is a cross-sectional view taken along line AA in FIG. 6(a)
  • FIG. 6(c) is a cross-sectional view taken along line BB in FIG. 6(a).
  • the solar cell element 30 with a current collecting sheet is arranged on the surface side of the current collecting sheet 20 and the sealing layer 54 of the current collecting sheet 20, and is connected to the wire 11 and It has a solar cell element 31 which is connected to the solar cell element 31.
  • FIGS. 6(a) to (c) show an example in which the current collecting sheet 20 has two current collecting sheet films 50, and a solar cell element 31 is arranged on each current collecting sheet film 50. It shows.
  • the film for current collector sheet in the present disclosure can impart barrier properties by having a transparent barrier layer. Therefore, when a current collector sheet with a current collector sheet film is used in a solar cell, the barrier properties can be improved by combining the current collector sheet film with a barrier film and the back protection sheet with a barrier film. It is possible to do so. Therefore, high barrier properties can be obtained without using a back protection sheet with metal foil or an expensive gas barrier film as the back protection sheet. Therefore, productivity can be increased and manufacturing costs can be reduced.
  • the film for current collector sheet in the present disclosure includes a transparent base material, a transparent barrier layer, an adhesive layer, and a sealing layer in this order.
  • the transparent barrier layer in the present disclosure is a member that is disposed on one surface of a transparent base material, has transparency, and has barrier properties against water vapor and oxygen. Further, the transparent barrier layer is usually a member constituting a barrier film.
  • the transparent barrier layer As for the transparency of the transparent barrier layer, if the current collector sheet film has transparency, it can be said that the transparent barrier layer has transparency. Specifically, as described later, it is preferable that the light transmittance and haze of the current collector sheet film at a wavelength of 400 nm or more and 1200 nm or less are within a predetermined range.
  • the transparent barrier layer if the current collector sheet film has barrier properties, it can be said that the transparent barrier layer has barrier properties. Specifically, as described later, it is preferable that the water vapor permeability of the current collector sheet film is within a predetermined range.
  • the transparent barrier layer has insulation properties. Thereby, the insulation properties of the current collector sheet film can be improved. Moreover, since the transparent barrier layer has insulation properties, there is no need to perform insulation treatment on the end face of the transparent barrier layer in the current collector sheet film. Therefore, productivity can be increased and manufacturing costs can be reduced.
  • the transparent barrier layer can be formed on one side of the transparent substrate, and is not particularly limited as long as it has barrier properties against water vapor and oxygen. Examples include inorganic hybrid membranes.
  • the inorganic compound contained in the inorganic compound film examples include inorganic oxides, inorganic oxynitrides, inorganic nitrides, inorganic oxycarbides, and inorganic oxycarbonitrides.
  • the inorganic compounds contained in the inorganic compound film include oxides, oxynitrides, etc. of silicon, aluminum, magnesium, calcium, potassium, tin, sodium, titanium, boron, yttrium, zirconium, cerium, zinc, etc. Examples include nitrides, oxidized carbides, oxidized carbonitrides, and the like.
  • silicon oxides such as SiOx
  • aluminum oxides such as AlyOz
  • magnesium oxides titanium oxides
  • titanium oxides tin oxides
  • silicon-zinc alloy oxides silicon-zinc alloy oxides
  • indium alloy oxides silicon nitrides.
  • the inorganic compounds may be used alone or in combination of two or more.
  • the inorganic compound contained in the inorganic compound film is preferably an inorganic compound containing silicon, more preferably a silicon oxide such as SiO x from the viewpoint of cost and performance.
  • the metal element contained in the inorganic compound is preferably the same type as the metal element in the metal alkoxide used in the overcoat layer described below.
  • the transparent barrier layer and the overcoat layer have the same metal element, the adhesion between the transparent barrier layer and the overcoat layer can be improved. Thereby, the barrier properties of the current collector sheet film can be improved.
  • barrier resin film examples include barrier resin films containing ethylene-vinyl alcohol copolymer, polyvinyl alcohol, polyvinylidene chloride, and the like.
  • the transparent barrier layer may be a single layer or a multilayer. In the case of multiple layers, the composition of each layer may be the same or different.
  • the transparent barrier layer may be a vapor deposited film, or may be a coated film formed by coating or the like.
  • the method for forming the transparent barrier layer is appropriately selected depending on the material and type of the transparent barrier layer. Examples include a vapor deposition method, a coating method, a pressure bonding method, and the like. Furthermore, when the transparent barrier layer is a barrier resin film, it may be formed by laminating the transparent base material and the transparent barrier layer by coextrusion.
  • the thickness of the transparent barrier layer is not particularly limited as long as desired barrier properties and transparency can be obtained, and is appropriately set depending on the type and configuration of the transparent barrier layer.
  • the thickness of the transparent barrier layer may be 5 nm or more and 200 nm or less, or 10 nm or more and 100 nm or less.
  • the thickness of the transparent barrier layer may be about several ⁇ m.
  • the thickness of the transparent barrier layer may be about several tens of ⁇ m. If the thickness of the transparent barrier layer is too thin, sufficient barrier properties may not be obtained. Furthermore, if the transparent barrier layer is too thick, cracks and the like may easily occur.
  • the film for a current collector sheet in the present disclosure does not have a metal layer as a barrier layer.
  • the metal layer usually has electrical conductivity. Since the current collector sheet film does not have a barrier layer having conductivity, insulation properties can be improved.
  • the metal layer is a layer made of metal or an alloy.
  • the metal layer may be, for example, a metal foil or a vapor deposited film. Note that the current collector sheet film usually does not have metal foil because it has transparency.
  • the transparent substrate in the present disclosure is, for example, a member that supports the transparent barrier layer.
  • the transparent base material has transparency if the current collector sheet film has transparency, similar to the above-mentioned transparent barrier layer.
  • the transparent base material has heat resistance.
  • the melting point of the transparent base material is preferably 200°C or higher, and preferably 250°C or higher.
  • the method for measuring the melting point of the transparent substrate is the same as the method for measuring the melting point of the polyethylene resin layer in the resin film for current collector sheet described above.
  • the transparent base material is not particularly limited as long as it has transparency and heat resistance and can support the transparent barrier layer.
  • the transparent base material is preferably a resin film containing a thermoplastic resin having the above melting point.
  • the thermoplastic resin having the above melting point include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), and the like.
  • PET polyethylene terephthalate
  • PET polyethylene terephthalate
  • PEN polyethylene naphthalate
  • PBT polybutylene terephthalate
  • PET polyethylene terephthalate
  • PET is preferred from the viewpoints of heat resistance, transparency, chemical resistance, water resistance, dimensional stability, cost, and the like.
  • the transparent base material can contain various additives as necessary.
  • additives include lubricants, crosslinking agents, antioxidants, light stabilizers, fillers, lubricants, reinforcing fibers, reinforcing agents, antistatic agents, flame retardants, flame retardants, foaming agents, antifungal agents, and modifiers.
  • resins for quality include resins for quality. The content of these additives is not particularly limited, and is appropriately adjusted depending on the purpose.
  • the transparent base material may be an unstretched resin film, or may be a uniaxially or biaxially stretched resin film.
  • the thickness of the transparent base material is not particularly limited as long as it can support the transparent barrier layer, and can be appropriately selected depending on the size and purpose of the solar cell in which the current collector sheet film is used. .
  • the thickness of the transparent base material is preferably thinner than the thickness of the sealing layer.
  • the thickness of the transparent base material is preferably 12 ⁇ m or more and 38 ⁇ m or less, more preferably 12 ⁇ m or more and 25 ⁇ m or less. If the thickness of the transparent substrate is too thin, it may be difficult to support the barrier layer. Moreover, if the thickness of the transparent base material is too thick, the rigidity will become too high, and the followability of the current collector sheet film to the wire may be reduced.
  • the surface of the transparent base material on the transparent barrier layer side may be surface-treated to improve adhesion with the transparent barrier layer. good.
  • a protective layer is disposed between the transparent barrier layer and the adhesive layer
  • the protective layer is a resin film
  • the protective layer and the transparent barrier layer constitute a barrier film
  • a transparent substrate can be laminated on the transparent barrier layer of the barrier film via a second adhesive layer.
  • a dry lamination method is preferably used. In the case of dry lamination, it is possible to suppress shearing of the transparent barrier layer during lamination.
  • the sealing layer in the present disclosure has thermal weldability and is a member that supports the wire when the current collector sheet film is used as the current collector sheet.
  • the resin contained in the sealing layer is usually a resin that has thermal weldability. Further, the resin contained in the sealing layer preferably has a property of wrapping around the wire when the current collecting sheet is thermocompression bonded to the solar cell element.
  • the above-mentioned property may be referred to as wire embeddability.
  • resins having heat-weldability and wire embedding properties include thermoplastic resins. Among them, from the viewpoint of transparency, the thermoplastic resin is preferably a polyolefin resin or an ionomer resin, and more preferably a polyolefin resin. The details of the polyolefin resin will be explained below.
  • the melting point of the polyolefin resin used for the sealing layer is not particularly limited as long as it can exhibit desired thermal weldability and wire embedding properties.
  • the melting point of the polyolefin resin is, for example, 125°C or lower, may be 120°C or lower, or may be 110°C or lower. Further, the melting point of the polyolefin resin is, for example, 80° C. or higher. If the melting point of the polyolefin resin is too high, it is necessary to raise the temperature when thermocompression bonding the current collector sheet to the solar cell element, which may increase manufacturing costs or cause the solar cell element to deteriorate. There is. On the other hand, if the melting point of the polyolefin resin is too low, the sealing layer may melt in the usage environment of the solar cell, making it difficult to fix the wire.
  • the method for measuring the melting point of the polyolefin resin is the same as the method for measuring the melting point of the polyethylene resin layer in the resin film for current collector sheet described above.
  • the polyolefin resin is preferably a polyethylene resin or a polypropylene resin, and more preferably a polyethylene resin. This is because wire embedding is excellent.
  • the type and density of the polyethylene resin are the same as the type and density of the polyethylene resin used in the polyethylene resin layer in the resin film for current collector sheet described above.
  • the sealing layer may contain only a polyolefin resin as a resin component, or may further contain a resin other than the polyolefin resin in addition to the polyolefin resin. In the latter case, the sealing layer preferably contains polyolefin resin as a main component. Note that the expression that the sealing layer contains polyolefin resin as a main component means that the proportion of polyolefin resin is the highest among all resin components.
  • the proportion of the polyolefin resin to all resin components in the sealing layer is, for example, 50% by mass or more, may be 60% by mass or more, or may be 70% by mass or more. Further, the proportion of the polyolefin resin may be, for example, 99% by mass or less, 95% by mass or less, or 90% by mass or less. Note that the proportion of the polyolefin resin may be 100% by mass.
  • Adhesiveness Improver The sealing layer in the present disclosure may contain an adhesiveness improver.
  • the adhesion improver is the same as the adhesion improver used for the polyethylene resin layer in the resin film for current collector sheet described above.
  • the thickness of the sealing layer is not particularly limited as long as it can support the wire when the current collector sheet film is used as the current collector sheet, and can be appropriately selected depending on the thickness of the wire.
  • the thickness of the sealing layer is preferably thicker than the thickness of the transparent base material, and also preferably thicker than the thickness of the protective layer described below. Thereby, the adhesion to the wire and the embeddability of the wire can be improved.
  • the thickness of the sealing layer is the same as the thickness of the polyethylene resin layer in the resin film for current collector sheet described above.
  • the surface of the sealing layer opposite to the adhesive layer may be subjected to surface treatment. That is, the sealing layer may have a surface treatment portion on the opposite side to the adhesive layer. Thereby, the adhesion to the wire and the adhesion to the solar cell element can be improved.
  • the surface treatment is similar to the surface treatment applied to the polyethylene resin layer in the resin film for current collector sheet described above.
  • Adhesive Layer is a member that is disposed between the barrier film having the transparent barrier layer described above and the sealing layer and for bonding the barrier film and the sealing layer.
  • the adhesive used for the adhesive layer is the same as the adhesive used for the adhesive layer in the resin film for current collector sheet described above.
  • the thickness of the adhesive layer is not particularly limited as long as it has transparency and can bond the barrier film and the sealing layer, and is preferably 0.1 ⁇ m or more and 10 ⁇ m or less, for example.
  • the film for current collector sheet in the present disclosure may have a protective layer 56 between the transparent barrier layer 52 and the adhesive layer 53, as shown in FIGS. 7(a) and 7(b), for example.
  • a transparent base material 51 and a transparent barrier layer 52 may constitute a barrier film 55
  • a protective layer 56 and a transparent The barrier layer 52 may constitute the barrier film 55.
  • the protective layer is a member that protects the transparent barrier layer. When a barrier film having a transparent barrier layer and a sealing layer are laminated via an adhesive layer, the transparent barrier layer can be protected by the protective layer.
  • the protective layer can suppress the wires from coming into contact with the transparent barrier layer. Thereby, it is possible to suppress the generation of cracks and the like in the transparent barrier layer due to the wire coming into contact with the transparent barrier layer, and the deterioration of the barrier properties.
  • a protective layer is preferably disposed between the transparent barrier layer and the adhesive layer.
  • shearing is applied to the transparent barrier layer, which may reduce the barrier properties of the transparent barrier layer. Therefore, during extrusion lamination, the transparent barrier layer can be protected by the protective layer, and deterioration of the barrier properties of the transparent barrier layer can be suppressed.
  • the protective layer is not particularly limited as long as it can protect the transparent barrier layer.
  • the material for the protective layer include resin.
  • the resin include polyolefin resin, polyester resin, cyclic polyolefin resin, polystyrene resin, acrylonitrile-styrene copolymer (AS resin), acrylonitrile-butadiene-styrene copolymer (ABS resin), poly(meth)acrylic resin, Examples include polycarbonate resin, polyvinyl alcohol resin, polyamide resin, polyimide resin, polyurethane resin, acetal resin, and cellulose resin. Examples of polyolefin resins include polyethylene and polypropylene.
  • polyester resin examples include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), and the like.
  • polyvinyl alcohol resin examples include polyvinyl alcohol (PVA) resin, ethylene-vinyl alcohol copolymer (EVOH) resin, and the like.
  • polyamide resin examples include various types of nylon.
  • polyester resins such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polybutylene terephthalate (PBT) are preferred from the viewpoint of heat resistance, transparency, chemical resistance, water resistance, dimensional stability, etc.
  • PET polyethylene terephthalate
  • PEN polyethylene naphthalate
  • PBT polybutylene terephthalate
  • PET polyethylene terephthalate
  • the protective layer can contain various additives as necessary.
  • the additives are the same as those used for the transparent base material.
  • the content of these additives is not particularly limited, and is appropriately adjusted depending on the purpose.
  • the protective layer may be a resin film, or may be a coating film such as coating.
  • the protective layer is a resin film
  • it may be an unstretched resin film or a uniaxially or biaxially stretched resin film.
  • the thickness of the protective layer is not particularly limited, and can be appropriately selected depending on the size and purpose of the solar cell in which the current collector sheet film is used. As mentioned above, the thickness of the protective layer is preferably thinner than the thickness of the sealing layer. Specifically, the thickness of the protective layer is preferably 12 ⁇ m or more and 38 ⁇ m or less. If the thickness of the protective layer is too thin, it may be difficult to adequately protect the transparent barrier layer. Moreover, if the thickness of the protective layer is too thick, the rigidity will become too high, and the followability of the current collector sheet film to the wire may deteriorate.
  • the method for disposing the protective layer on the transparent barrier layer includes, for example, applying a second adhesive on the transparent barrier layer of the barrier film.
  • a method of laminating protective layers via layers can be mentioned. In this case, a dry lamination method is preferably used. In the case of dry lamination, it is possible to suppress shearing of the transparent barrier layer during lamination.
  • the method for forming the protective layer is appropriately selected depending on the material and type of the protective layer, and various coating methods can be used.
  • the protective layer is a resin film and the barrier film has a protective layer and a transparent barrier layer
  • the surface of the protective layer on the transparent barrier layer side may be subjected to surface treatment to improve adhesion with the transparent barrier layer. may have been applied.
  • Overcoat layer The film for current collector sheet in the present disclosure may have an overcoat layer 57 between the transparent barrier layer 52 and the adhesive layer 53, as shown in FIGS. 7(c) and 7(d), for example. good.
  • the overcoat layer is usually a member that constitutes a barrier film together with the transparent barrier layer.
  • an overcoat layer 57 is arranged between the transparent barrier layer 52 and the protective layer 56.
  • an overcoat Layer 57 is disposed between transparent substrate 51 and transparent barrier layer 52.
  • the overcoat layer may contain only an organic substance, or may contain a mixture of an inorganic substance and an organic substance. Among these, it is preferable that the overcoat layer contains a mixture of an inorganic substance and an organic substance. Water vapor barrier properties can be improved.
  • the overcoat layer preferably contains a hydrolyzed polycondensate produced from a resin composition containing a metal alkoxide and a hydrophilic group-containing resin. Water vapor barrier properties can be improved.
  • Examples of the metal alkoxide include one or more alkoxides represented by the following general formula.
  • R 1 n M(OR 2 ) m (However, in the above formula, R 1 and R 2 represent an organic group having 1 or more and 8 or less carbon atoms, M represents a metal atom, n represents an integer of 0 or more, and m is 1 or more. represents an integer, and n+m represents the valence of M.)
  • Examples of the metal atom M of the alkoxide represented by the above formula include silicon, zirconium, titanium, and aluminum. Among them, silicon is preferred.
  • n 0.
  • the silicon alkoxide is preferably tetraethoxysilane (TEOS).
  • the alkoxide represented by the above formula at least one of partial hydrolysates of alkoxides and hydrolyzed condensates of alkoxides can be used.
  • the partial hydrolyzate of the alkoxide is not limited to one in which all of the alkoxy groups are hydrolyzed, but may be one in which one or more alkoxy groups are hydrolyzed, or a mixture thereof.
  • the condensate for hydrolysis a dimer or more of partially hydrolyzed alkoxide, specifically a dimer to hexamer, may be used.
  • hydrophilic group-containing resin examples include resins containing hydrophilic groups.
  • resins containing hydrophilic groups include polyvinyl alcohol resins, ethylene-vinyl alcohol copolymers, acrylic acid resins, natural polymers such as methyl cellulose, carboxymethyl cellulose, cellulose nanofibers, and polysaccharides.
  • polyvinyl alcohol resin is preferred.
  • the content of the hydrophilic group-containing resin in the resin composition is, for example, preferably 5 parts by mass or more and 20 parts by mass or less, more preferably 7 parts by mass or more and 18 parts by mass or less, based on 100 parts by mass of the metal alkoxide content. .
  • the above-mentioned hydrolyzed polycondensate can be a mixed compound containing a metal element, an oxygen element, and a hydrophilic group-containing resin, and the carbon atom (C) in the hydrophilic group-containing resin and the metal atom (M ) can have a C--O--M bond via oxygen (O).
  • the hydrolyzed polycondensate is a polycondensate of tetraethoxysilane (TEOS) and a polyvinyl alcohol resin.
  • TEOS tetraethoxysilane
  • TEOS tetraethoxysilane
  • polyvinyl alcohol resin is the same as that disclosed in, for example, Japanese Patent No. 5,568,897.
  • the overcoat layer may contain various additives as necessary.
  • the thickness of the overcoat layer is not particularly limited, but may be, for example, 100 nm or more and 4 ⁇ m or less, and may be 200 nm or more and 1 ⁇ m or less. If the thickness of the overcoat layer is within the above range, it is possible to suppress the occurrence of cracks and the like while maintaining high barrier properties.
  • Examples of the method for forming the overcoat layer containing the hydrolyzed polycondensate include a thin film forming method using a sol-gel method. That is, this method uses a raw material liquid containing a metal alkoxide and a hydrophilic group-containing resin, which is further obtained by polycondensation using a sol-gel method. Specifically, first, a metal alkoxide or a hydrolyzate thereof is mixed with a solution in which a hydrophilic group-containing resin is dissolved in an aqueous solvent to prepare a coating liquid. As the aqueous solvent, for example, water or a mixed solvent of water and alcohol can be used. Next, the coating liquid is applied onto the transparent barrier layer, dried by heating, and subjected to heat treatment. As a result, an overcoat layer containing the above hydrolyzed polycondensate is obtained.
  • a sol-gel method uses a raw material liquid containing a metal alkoxide and a hydrophilic group-containing resin, which is further
  • the thickness of the current collector sheet film in the present disclosure is the same as the thickness of the above-mentioned current collector sheet resin film.
  • the film for current collector sheet in the present disclosure has water vapor barrier properties by having a transparent barrier layer.
  • the water vapor permeability of the current collector sheet film is, for example, preferably 1 ⁇ 10 ⁇ 3 g/(m 2 ⁇ day) or more and 1 g/(m 2 ⁇ day) or less, and 1 ⁇ 10 ⁇ 3 g/(m 2 ⁇ day) or less. ⁇ day) or more and 1 ⁇ 10 ⁇ 1 g/(m 2 ⁇ day) or less is more preferable, and 1 ⁇ 10 ⁇ 3 g/(m 2 ⁇ day) or more and 1 ⁇ 10 ⁇ 2 g/(m 2 ⁇ day) ) The following are more preferable.
  • the water vapor permeability is measured in accordance with ISO 15106-5:2015 (differential pressure method) under conditions of a temperature of 40° C. and a relative humidity difference of 90% RH using a water vapor permeability measuring device.
  • a water vapor permeability measuring device "DELTAPERM” manufactured by Technolox, UK is used. The measurement was performed so that the surface of the current collector sheet film that is located on the transparent barrier layer side with respect to the transparent base material in the thickness direction of the current collector sheet film is the high humidity side (water vapor supply side).
  • a current collector sheet film was installed between the upper and lower chambers of the water vapor permeability measuring device, and the measurement was conducted under the above conditions with a permeation area of 50.24 cm 2 (permeation area: circular 8 cm in diameter). At least three samples are measured under one condition, and the average of those measured values is taken as the water vapor permeability value under that condition.
  • Light transmittance at a wavelength of 400 nm or more and 1200 nm or less The light transmittance of the film for a current collector sheet in the present disclosure at a wavelength of 400 nm or more and 1200 nm or less is the same as the light transmittance of the above-mentioned resin film for a current collector sheet at a wavelength of 400 nm or more and 1200 nm or less. be.
  • the transparency of the current collector sheet film in the present disclosure is not particularly limited as long as it can transmit sunlight to the extent that the solar cell element can generate electricity.
  • the transparency of the current collector sheet film can be evaluated, for example, by haze.
  • the haze of the current collector sheet film is the same as the haze of the above-mentioned current collector sheet resin film.
  • a measurement sample is prepared and used for measurement.
  • the method for preparing the sample for measurement is the same as the method for preparing the sample for measurement when measuring the haze of the resin film for current collector sheet described above.
  • Method for producing a film for a current collector sheet is such that a film for a current collector sheet having a transparent base material, a transparent barrier layer, an adhesive layer, and a sealing layer in this order can be obtained. Not particularly limited.
  • a method in which a barrier film having a transparent base material and a transparent barrier layer and a film-like sealing layer are used and the barrier film and the sealing layer are laminated via a dry laminating adhesive by a dry lamination method examples include a method in which a barrier film having a transparent base material and a transparent barrier layer is used, and a sealing layer is extruded onto the barrier film and laminated via an anchor coating agent for lamination by an extrusion lamination method.
  • the film for current collector sheet has a transparent base material, a transparent barrier layer, a protective layer, an adhesive layer, and a sealing layer in this order, for example, a barrier film having a transparent base material and a transparent barrier layer
  • a barrier film having a transparent base material and a transparent barrier layer A method in which a film-like protective layer and a film-like sealing layer are used, and each film is laminated via an adhesive using a dry lamination method or an extrusion lamination method, or a film-like transparent base material and a transparent barrier layer are used.
  • Another method includes a method in which a barrier film having a protective layer and a film-like sealing layer are used, and each film is laminated via an adhesive by a dry lamination method or an extrusion lamination method.
  • Examples of the method for producing a barrier film include a method of using a film-like transparent base material or a protective layer and forming a transparent barrier layer on the transparent base material or the protective layer. Furthermore, in the method for producing a barrier film, an overcoat layer may be formed on the transparent barrier layer. The method for forming the transparent barrier layer and the method for forming the overcoat layer are as described above.
  • the method for forming the film-like sealing layer is the same as the method for forming the film-like polyethylene resin layer in the resin film for current collector sheet described above.
  • the current collector sheet in the present disclosure has two embodiments.
  • the first embodiment of the current collector sheet in the present disclosure is a current collector sheet used for a solar cell, which comprises the above-mentioned resin film for current collector sheet and resin film for current collector sheet. and a wire disposed on the surface side of the polyethylene resin layer.
  • FIGS. 2A and 2B are a schematic plan view and a cross-sectional view illustrating the current collector sheet of this embodiment
  • FIG. 2(b) is a cross-sectional view taken along the line AA in FIG. 2(a).
  • the current collector sheet 20 includes a resin film 10 for a current collector sheet, and a wire 11 disposed on the surface side of the polyethylene resin layer 3 of the resin film 10 for a current collector sheet. and has.
  • FIG. 2(a) shows a schematic plan view of the current collecting sheet viewed from the polyethylene resin layer side of the resin film for current collecting sheet.
  • the wire can be well fixed to the solar cell element by the resin film for current collecting sheet. Moreover, the resin film for the current collector sheet can suppress the displacement of the wire due to heat. Therefore, when the current collecting sheet is used in a solar cell, power generation efficiency can be improved and reliability can be improved.
  • the current collector sheet of this embodiment includes a resin film for a current collector sheet and a wire.
  • Resin film for current collector sheet The resin film for current collector sheet is a member that supports the wire. Moreover, the resin film for current collector sheet is a member that fixes the wire to the solar cell element.
  • the resin film for the current collector sheet is the same as that explained in "A. Resin film for the current collector sheet" above, so the explanation here will be omitted.
  • the current collecting sheet has a plurality of resin films for current collecting sheet
  • at least one resin film for current collecting sheet may be the above-mentioned resin film for current collecting sheet.
  • the current collector sheet may have a resin film for current collector sheet other than the above-mentioned resin film for current collector sheet.
  • Wire The wire is arranged on the surface side of the polyethylene resin layer of the resin film for current collector sheet. Wires are used, for example, in solar cell modules to connect solar cell elements to each other. Further, the wire is used, for example, in a single cell type solar cell to collect electricity generated in a solar cell element. The wire is usually arranged to connect with the electrode of the solar cell element.
  • the cross-sectional shape of the wire is typically circular, such as a perfect circle or an ellipse, but is not limited thereto.
  • the thickness of the wire that is, the size of the cross section of the wire, is not particularly limited as long as it does not prevent sunlight from entering the solar cell element, and is, for example, 100 ⁇ m or more and 300 ⁇ m or less.
  • the cross-sectional size of the wire is, for example, the diameter when the cross-section is circular, the major axis when the cross-section is elliptical, and the maximum diagonal length when the cross-section is polygonal.
  • the material of the wire is not particularly limited as long as it can exhibit the desired conductivity, and is similar to the material of the wire used in current collector sheets of general solar cell elements.
  • the material of the wire for example, metal materials such as copper (Cu) and silver (Ag) can be used.
  • the wire may have, for example, a core portion and a skin portion disposed on the outside of the core portion.
  • the material of the core part for example, the above metal materials can be used.
  • solder can be used as the material for the skin portion.
  • the melting point of the solder is, for example, preferably 70°C or more and 140°C or less, more preferably 80°C or more and 135°C or less. If the melting point of the solder is too high, there is a possibility that the base material layer and the polyethylene resin layer described above will deteriorate when connecting wires to the solar cell element.
  • solder examples include Sn--In based solder, Bi--Sn based solder, and the like.
  • Bi-Sn-based solder has a higher melting point. Therefore, when using Bi-Sn solder, the heating temperature in the heating process when manufacturing a solar cell element with a current collector sheet and the solar cell element with a current collector sheet must be adjusted. The heating temperature in the heating process when manufacturing solar cells tends to be high. Therefore, in the above case, poor adhesion of the wires and misalignment of the wires are likely to occur. Therefore, this embodiment is particularly effective in the above case.
  • At least one or more wires may be arranged for one resin film for current collecting sheet. From the viewpoint of increasing the conductivity of the current collector sheet, it is preferable that a plurality of wires are arranged for one resin film for current collector sheet.
  • the arrangement of the wires in plan view is not particularly limited, and is similar to the arrangement of the wires in known current collector sheets.
  • the wires 11 may be arranged in a line, or, although not shown, the wires may be arranged in a grid.
  • the wire is arranged on the surface side of the polyethylene resin layer of the resin film for the current collector sheet.
  • the wire 11 is arranged so that a part of the wire 11 is embedded in the polyethylene resin layer 3 of the resin film 10 for current collector sheet, and a part of the wire 11 is exposed.
  • Wires can be fixed well.
  • the wire 11 may be embedded in the polyethylene resin layer 3 so as not to contact the base material layer 1, and as shown in FIG. It may be embedded in the polyethylene resin layer 3 so as to be in contact with the layer 1 .
  • the thickness of the current collector sheet can be reduced, so that the solar cell using the current collector sheet can be made thinner.
  • the degree of embedding of the wires is not particularly limited and depends on the material and thickness of the polyethylene resin layer, the thickness of the wires, and the form of the solar cell element in which the current collector sheet is arranged. You can choose as appropriate.
  • the same wire may be arranged on a plurality of resin films for current collecting sheets.
  • FIG. 9 shows an example in which the same wire 11 is arranged for two resin films 10A and 10B for current collector sheets.
  • adjacent resin films 10A and 10B for current collector sheets may be arranged so that the surfaces facing the polyethylene resin layer 3 are opposite to each other. That is, the surface of one resin film for current collector sheet 10A on the polyethylene resin layer 3 side and the surface of the other resin film for current collector sheet 10B on the base material layer 1 side are arranged in the same surface direction. Good too.
  • the current collector sheet 20 can be made into a current collector sheet 20 in which two solar cell elements 31 can be arranged in series, as shown in FIG. 3(a), for example.
  • adjacent resin films for current collector sheets may be arranged so that their surfaces facing the polyethylene resin layer are in the same surface direction.
  • the method for manufacturing the current collector sheet of this embodiment is particularly limited as long as it is a method that can embed wires to the surface side of the polyethylene resin layer of the resin film for current collector sheet to the extent that they can be fixed.
  • a known method can be used.
  • One example is a method in which a wire is placed on the side of the polyethylene resin layer of a resin film for a current collector sheet, and by heating the wire, a part of the polyethylene resin in the polyethylene resin layer is melted and the wire is embedded. be able to.
  • the second embodiment of the current collector sheet in the present disclosure is a current collector sheet used for a solar cell, and includes the above-mentioned current collector sheet film and sealing of the current collector sheet film. and a wire disposed on the surface side of the layer.
  • FIGS. 5(a) and 5(b) are a schematic plan view and a cross-sectional view illustrating the current collector sheet of this embodiment
  • FIG. 5(b) is a cross-sectional view taken along the line AA in FIG. 5(a).
  • the current collecting sheet 20 includes a current collecting sheet film 50 and a wire 11 disposed on the surface side of the sealing layer 54 of the current collecting sheet film 50.
  • FIG. 5(a) shows a schematic plan view of the current collecting sheet viewed from the sealing layer side of the film for current collecting sheet.
  • barrier properties can be imparted by having the above-described film for current collector sheet. Therefore, when the current collector sheet is used in a solar cell, barrier properties can be improved and reliability can be improved.
  • the current collector sheet of this embodiment includes a current collector sheet film and a wire.
  • Film for current collector sheet The film for current collector sheet is a member that supports the wire. Further, the current collector sheet film is a member that fixes the wire to the solar cell element.
  • the current collecting sheet has a plurality of current collecting sheet films
  • at least one current collecting sheet film may be the above-mentioned current collecting sheet film.
  • the current collecting sheet may have a current collecting sheet film other than the above-mentioned current collecting sheet film.
  • it is preferable that all of the plurality of current collecting sheet films included in the current collecting sheet are the above-mentioned current collecting sheet films.
  • the wire is arranged on the surface side of the sealing layer of the current collector sheet film.
  • the wire is the same as the wire in the first embodiment of the current collector sheet described above.
  • solder used for the skin part examples include Sn-In-Ag-Bi-based, Sn-In-based, Bi-Sn-based, and the like.
  • the wire 11 is attached to the transparent barrier layer 52 as shown in FIG. 5(b). It is preferable that they be embedded in the sealing layer 54 so as not to contact each other.
  • the wire 11 does not come into contact with the protective layer 56, as shown in FIG. 10(a).
  • the wire 11 may be embedded in the sealing layer 54 so as to be in contact with the protective layer 56.
  • the thickness of the current collector sheet can be reduced, so that the solar cell using the current collector sheet can be made thinner.
  • the method for manufacturing the current collector sheet of this embodiment is not particularly limited as long as it is a method that can embed the wire to the side of the sealing layer of the film for current collector sheet to an extent that it can be fixed. , a known method can be used.
  • One example is a method in which a wire is placed on the side of the sealing layer of the current collector sheet film, and the wire is heated to melt part of the resin component in the sealing layer and embed the wire. I can do it.
  • the solar cell element with current collector sheet in the present disclosure has two embodiments.
  • the first embodiment of a solar cell element with a current collector sheet in the present disclosure includes the above-mentioned current collector sheet, and a current collector sheet arranged on the surface side of the polyethylene resin layer, A solar cell element electrically connected to the wire.
  • 3(a) to 3(c) are a schematic perspective view and a sectional view illustrating a solar cell element with a current collector sheet according to the present embodiment
  • FIG. 3(b) is a line AA in FIG. 3(a).
  • 3(c) is a sectional view taken along line BB in FIG. 3(a).
  • the solar cell element 30 with a current collector sheet is arranged on the surface side of the current collector sheet 20 and the polyethylene resin layer 3 of the current collector sheet 20, and is connected to the wire 11 and It has a solar cell element 31 which is connected to the solar cell element 31.
  • 3(a) to (c) are examples in which the current collecting sheet 20 has two resin films 10 for current collecting sheets, and a solar cell element 31 is arranged on each resin film 10 for current collecting sheets. It shows.
  • the wire can be well fixed to the solar cell element by the resin film for the current collector sheet. Moreover, the resin film for the current collector sheet can suppress the displacement of the wire due to heat. Therefore, when a solar cell element with a current collector sheet is used in a solar cell, power generation efficiency can be improved and reliability can be improved.
  • the solar cell element with current collector sheet of this embodiment includes a current collector sheet and a solar cell element.
  • the current collecting sheet is the same as that described in the above-mentioned "C. Current Collecting Sheet C-1. First Embodiment of Current Collecting Sheet", so a description thereof will be omitted here.
  • the solar cell element with a current collecting sheet has a plurality of current collecting sheets
  • at least one current collecting sheet may be the above-mentioned current collecting sheet.
  • the solar cell element with a current collecting sheet may have a current collecting sheet other than the above-mentioned current collecting sheet.
  • it is preferable that all the current collecting sheets are the above-mentioned current collecting sheets.
  • the solar cell element is similar to the element used in general solar cells.
  • Examples of the solar cell element include a single crystal silicon solar cell element, a polycrystalline silicon solar cell element, an amorphous silicon solar cell element, a compound semiconductor solar cell element, a dye-sensitized solar cell element, and a quantum dot solar cell element.
  • Examples include battery elements, organic thin film type solar cell elements, and the like. The size, form, etc. of the solar cell element can be appropriately selected depending on the use of the solar cell.
  • a solar cell element with a current collector sheet usually has a laminated structure in which a current collector sheet and a solar cell element are laminated.
  • the thickness of the resin film 10 that is, the distance from the surface of the solar cell element 31 on which the current collector sheet 20 is arranged to the surface of the base material layer 1 on the opposite side to the solar cell element 31, is determined by the distance on which the wire 11 is arranged. It is preferable that the region is thicker (distance is larger) than other regions.
  • the maximum distance y of the wire 11 in the direction D L perpendicular to the arrangement surface that is, the maximum distance y of the wire 11 from the surface on which the current collector sheet 20 of the solar cell element 31 is arranged, and the maximum distance y of the wire 11 in the direction D L perpendicular to the arrangement surface.
  • the minimum distance x of the current collector sheet resin film 10 of L that is, the distance from the surface of the solar cell element 31 on which the current collector sheet 20 is arranged to the surface of the base material layer 1 on the opposite side from the solar cell element 31
  • the ratio x/y with respect to the minimum distance x is, for example, preferably 2/3 or less, more preferably 1/2 or less.
  • the lower limit of the ratio x/y is a value that is appropriately adjusted depending on the thickness of the polyethylene resin layer and the thickness of the wire, and is, for example, 1/20 or more.
  • the wire can be well fixed to the solar cell element using the resin film for current collector sheet.
  • the above ratio x/y can be controlled by adjusting the thickness (diameter, etc.) of the wire and the thickness of the polyethylene resin layer. Further, as will be described later, the ratio x/y can also be controlled by adjusting the pressure when thermocompression bonding the current collector sheet to the solar cell element.
  • the solar cell element 31 is It is preferable that the distance from the surface on the current collector sheet 20 side to the surface of the base material layer 1 on the opposite side to the solar cell element 31 gradually decreases.
  • the distance from the surface on which the sheet 20 is disposed to the surface of the base layer 1 opposite to the solar cell element 31 is disposed at the minimum distance. Since depressions are formed between the wires and the current collector sheet has an uneven structure, the area of the surface of the base material layer opposite to the solar cell element becomes large. Thereby, in a solar cell having a solar cell element with a current collector sheet, the contact area between the base layer and the encapsulant described later becomes large, so that adhesion to the encapsulant can be improved.
  • the wire 11 may be embedded in the polyethylene resin layer 3 so as to be in contact with the base layer 1. Thereby, the thickness of the solar cell element with the current collecting sheet can be reduced, so that the solar cell can be made thinner.
  • the solar cell element with a current collecting sheet may include at least one solar cell element and a current collecting sheet connected to at least one of the positive and negative electrodes of the solar cell element.
  • it may be a solar cell element with a current collecting sheet that constitutes a single cell type solar cell, in which a current collecting sheet is placed on each of the positive electrode and the negative electrode of one solar cell element.
  • a solar cell element with a current collector sheet is a solar cell with a current collector sheet that constitutes a solar cell module type solar cell (solar cell module) in which multiple solar cell elements are connected in parallel or in series using a current collector sheet. It may also be a solar cell element.
  • the method for manufacturing the solar cell element with a current collector sheet of this embodiment is not particularly limited as long as it is a method that can obtain a structure in which the wires of the current collector sheet are electrically connected and fixed to the solar cell element. .
  • a manufacturing method includes a fixing step of physically connecting and fixing.
  • known methods can be used, such as a vacuum thermal lamination method.
  • the fixing step may be performed at the same time as the unifying step of laminating and integrating the respective members of the solar cell, for example, as described in the section "E. Solar Cell" below.
  • a solar cell element with a current collector sheet is normally used as a member constituting a solar cell.
  • a solar cell element with a current collector sheet has, for example, one solar cell element and a current collector sheet connected to only one electrode of the positive electrode or the negative electrode of the solar cell element, the solar cell element with a current collector sheet
  • the solar cell element can be used, for example, as a part of the above-mentioned single-cell type solar cell, or as a part of the solar cell element with a current collector sheet that constitutes the above-mentioned solar cell module.
  • Second embodiment of the solar cell element with a current collector sheet includes the above-mentioned current collector sheet, and the current collector sheet is arranged on the surface side of the sealing layer, A solar cell element electrically connected to the wire.
  • FIGS. 6(a) to 6(c) are a schematic perspective view and a cross-sectional view illustrating a solar cell element with a current collector sheet according to the present embodiment
  • FIG. 6(b) is a line AA in FIG. 6(a).
  • FIG. 6(c) is a sectional view taken along line BB in FIG. 6(a).
  • the solar cell element 30 with a current collecting sheet is arranged on the surface side of the current collecting sheet 20 and the sealing layer 54 of the current collecting sheet 20, and is connected to the wire 11 and It has a solar cell element 31 which is connected to the solar cell element 31.
  • 6(a) to (c) show an example in which the current collecting sheet 20 has two current collecting sheet films 50, and a solar cell element 31 is arranged on each current collecting sheet film 50. ing.
  • barrier properties can be imparted by having the second embodiment of the current collector sheet described above. Therefore, when a solar cell element with a current collector sheet is used in a solar cell, barrier properties can be improved and reliability can be improved.
  • the solar cell element with current collector sheet of this embodiment includes a current collector sheet and a solar cell element.
  • the current collecting sheet is the same as that described in the above-mentioned "C. Current Collecting Sheet C-2. Second Embodiment of Current Collecting Sheet", so a description thereof will be omitted here.
  • the solar cell element with a current collector sheet has a plurality of current collector sheets is the same as the first embodiment of the solar cell element with a current collector sheet described above.
  • the case where the solar cell element with a current collector sheet is used as a solar cell is the same as the first embodiment of the solar cell element with a current collector sheet described above.
  • the solar cell element is similar to the solar cell element in the first embodiment of the solar cell element with a current collector sheet described above.
  • the film for the current collector sheet has a protective layer between the transparent barrier layer and the adhesive layer, the above-mentioned “C. Current collector sheet C-2.
  • Current collector sheet Although not shown, the wire may be embedded in the sealing layer so as to be in contact with the protective layer, as described in the section "Second Embodiment". Thereby, the thickness of the solar cell element with the current collecting sheet can be reduced, so that the solar cell can be made thinner.
  • the method for manufacturing the solar cell element with a current collector sheet of this embodiment is the same as the method of manufacturing the solar cell element with a current collector sheet of the first embodiment described above. Furthermore, the case where the solar cell element with a current collecting sheet is used in a solar cell is similar to the first embodiment of the solar cell element with a current collecting sheet described above.
  • the solar cell in this disclosure has two embodiments.
  • the first embodiment of the solar cell according to the present disclosure includes a transparent substrate, a first encapsulant, the above-described solar cell element with a current collector sheet, a second encapsulant, and a counter substrate. and in this order.
  • FIG. 11 is a schematic cross-sectional view illustrating the solar cell of this embodiment.
  • the solar cell 40 includes a transparent substrate 41, a first encapsulant 42, a solar cell element 30 with a current collector sheet, a second encapsulant 43, and a counter substrate 44.
  • the solar cell of this embodiment may be a solar cell module having a plurality of solar cell elements with current collecting sheets.
  • the wire can be well fixed to the solar cell element by the resin film for the current collecting sheet. Moreover, the resin film for the current collector sheet can suppress the displacement of the wire due to heat. Therefore, power generation efficiency can be improved and reliability can be improved.
  • the solar cell of this embodiment includes, in this order, a transparent substrate, a first encapsulant, a solar cell element with a current collector sheet, a second encapsulant, and a counter substrate.
  • the transparent substrate is a member that protects the solar cell element together with the counter substrate. Further, the transparent substrate is usually arranged on the light-receiving surface side of the solar cell, and functions as a front protection plate on the light-receiving surface side.
  • the transparency of the transparent substrate is not particularly limited as long as it does not inhibit the power generation of the solar cell element. Since the transparent substrate is the same as a transparent substrate used in a general solar cell, a description thereof will be omitted here.
  • the counter substrate is a member that protects the solar cell element together with the transparent substrate.
  • the counter substrate may or may not have transparency. When the counter substrate has transparency, both surfaces of the solar cell can be used as sunlight receiving surfaces.
  • the counter substrate the above-mentioned transparent substrate can be used. Further, as the counter substrate, a back protection sheet for solar cells can also be used.
  • first Encapsulant and the second encapsulant are members that seal the solar cell element.
  • the first sealing material is usually placed on the light-receiving surface side of the solar cell.
  • the first sealing material and the second sealing member contain thermoplastic resin.
  • the thermoplastic resin used for the first encapsulant and the second encapsulant is the same as the thermoplastic resin used for the encapsulant of general solar cells, such as polyethylene resin, ethylene-vinyl acetate, etc.
  • Encapsulants mainly composed of various olefin resins such as polymers (EVA) can be used.
  • EVA polymers
  • the first sealing material usually contains an ultraviolet absorber. Deterioration of the base material layer containing polyethylene terephthalate resin caused by ultraviolet rays, such as yellowing, cracking, and breakage, can be suppressed.
  • the second encapsulant usually contains an ultraviolet absorber, similar to the first encapsulant.
  • the ultraviolet absorber is similar to the ultraviolet absorber used in general solar cell encapsulants.
  • the thicknesses of the first encapsulant and the second encapsulant are appropriately selected depending on the type and size of the solar cell.
  • the method for manufacturing a solar cell in this embodiment is similar to the method for manufacturing a general solar cell.
  • the heating and pressure treatments are not particularly limited, and are similar to those performed during the manufacture of general solar cells.
  • a vacuum thermal lamination method is preferred.
  • the conditions for the vacuum thermal lamination method are not particularly limited, and can be appropriately selected depending on the size of the solar cell, the type of each member, etc.
  • the lamination temperature is preferably, for example, 130°C or higher and 170°C or lower.
  • the lamination time is preferably, for example, 5 minutes or more and 30 minutes or less, and more preferably 8 minutes or more and 15 minutes or less.
  • a second embodiment of the solar cell according to the present disclosure includes a transparent substrate, a first encapsulant, the above-described solar cell element with a current collector sheet, a second encapsulant, and a back surface protection. Place the sheets and in this order.
  • the schematic cross-sectional view illustrating the solar cell of this embodiment is the one in FIG. 11 of the first embodiment of the solar cell described above, in which the "counter substrate 44" is replaced with a "back protection sheet”.
  • the solar cell of this embodiment may be a solar cell module having a plurality of solar cell elements with current collecting sheets.
  • the solar cell of this embodiment includes, in this order, a transparent substrate, a first encapsulant, a solar cell element with a current collector sheet, a second encapsulant, and a back protection sheet.
  • the back protection sheet is a member that protects the solar cell element together with the transparent substrate.
  • the back protection sheet may or may not have transparency. When the back protection sheet has transparency, both sides of the solar cell can be used as sunlight receiving surfaces.
  • the back protection sheet is similar to the back protection sheet used for general solar cells.
  • the back protection sheet has an easily adhesive layer, a second barrier film, and a base material layer in this order from the second encapsulant side, which will be described later.
  • the barrier film included in the back protection sheet is referred to as a second barrier film.
  • the second barrier film can have a base material and a barrier layer.
  • the second barrier film is usually arranged such that the base material is on the easily adhesive layer side and the barrier layer is on the base material layer side.
  • the barrier layer may or may not have transparency.
  • the barrier layer is the same as the transparent barrier layer used in the current collector sheet film, so the explanation here will be omitted.
  • the base material may or may not have transparency.
  • the base material is the same as the transparent base material used in the above-mentioned current collector sheet film, so the explanation here will be omitted.
  • the second barrier film preferably has a second overcoat layer on the side of the barrier layer opposite to the base material. Barrier properties can be improved.
  • the second overcoat layer is the same as the overcoat layer used in the above-mentioned current collector sheet film, so a description thereof will be omitted here.
  • the base material layer is the same as the base material layer that constitutes a back protection sheet used in general solar cells.
  • a resin film having weather resistance can be used as the base material layer.
  • the easy-adhesion layer is a member for increasing the adhesion between the back protection sheet and the second sealing material.
  • the easily adhesive layer is the same as the easily adhesive layer that constitutes a back protection sheet used in general solar cells. Examples of the easily adhesive layer include polyethylene film.
  • a third adhesive layer may be disposed between the base layer and the second gas barrier film. Further, in the back protection sheet, a fourth adhesive layer may be disposed between the second gas barrier film and the easily adhesive layer.
  • the third adhesive layer and the fourth adhesive layer are the same as the adhesive layer used in the above film for current collector sheet.
  • the transparent substrate is the same as the transparent substrate in the first embodiment of the solar cell described above.
  • First encapsulant and second encapsulant are the same as the first encapsulant and second encapsulant in the first embodiment of the solar cell described above.
  • Example 1 A polyethylene terephthalate (PET) film ("LBD” manufactured by DuPont) with a thickness of 12 ⁇ m was used as the base material layer.
  • PET polyethylene terephthalate
  • an adhesive an adhesive (anchor coating agent) a two-component type consisting of a polycarbonate-based main agent ("KT-0035” manufactured by Rock Paint Co., Ltd.) and an isocyanate-based curing agent ("H-039Z2" manufactured by Rock Paint Co., Ltd.) is used. Glue was used.
  • LDPE high-pressure low density polyethylene
  • 0.1 g/m 2 of the adhesive was applied as an anchor agent, and the polyethylene resin was extruded to a thickness of 60 ⁇ m to form a polyethylene resin layer. Furthermore, the surface of the polyethylene resin layer opposite to the base material layer was subjected to corona treatment. Thereby, a resin film for a current collector sheet having a base material layer, an adhesive layer, and a polyethylene resin layer in this order was obtained.
  • Example 2 A resin film for a current collector sheet was produced in the same manner as in Example 1, except that the base layer was annealed at 200° C. for 10 seconds.
  • a resin film for a current collector sheet was produced in the same manner as in Example 1.
  • a 12 ⁇ m thick polyethylene terephthalate (PET) film (“E5104” manufactured by Toyobo Co., Ltd.) was used as the base material layer.
  • PET polyethylene terephthalate
  • an adhesive an adhesive (anchor coating agent)
  • a two-component type consisting of a polycarbonate-based main agent ("KT-0035” manufactured by Rock Paint Co., Ltd.) and an isocyanate-based curing agent ("H-039Z2" manufactured by Rock Paint Co., Ltd.) is used.
  • Glue was used as an adhesive (anchor coating agent).
  • polyethylene resin layer a polyethylene film containing metallocene linear low density polyethylene (M-LLDPE) having a density of 0.915 g/cm 3 , a melting point of 105° C., and an MFR (190° C.) of 2 g/10 minutes was used.
  • M-LLDPE metallocene linear low density polyethylene
  • a resin film for a current collector sheet was obtained by bonding the base material layer and the polyethylene resin layer together via an adhesive using a dry lamination method.
  • a resin film for a current collector sheet was produced in the same manner as in Example 1 except that the thickness of the polyethylene resin layer was 70 ⁇ m.
  • a test piece was prepared by cutting a resin film for a current collector sheet into a size of 50 mm x 50 mm. Next, the ETFE (tetrafluoroethylene-ethylene copolymer) film, the test piece, and the ETFE film were laminated in this order, and vacuum laminated at a set temperature of 165°C, vacuuming for 2 minutes, pressing for 2.5 minutes, and pressure of 100 kPa. I did it. Subsequently, the ETFE film was removed from both sides of the test piece to obtain a measurement sample. Then, the haze of the measurement sample was measured in accordance with JIS K7136 using a haze meter HM150 manufactured by Murakami Color Research Institute.
  • Wire Adhesion Wire A coated with SnIn-based solder and Wire B coated with SnBi-based solder were used as wires.
  • the diameters of wire A and wire B were each 250 ⁇ m.
  • a test piece was prepared by cutting the resin film for current collector sheet into a size of 100 mm x 100 mm. Next, an ETFE (tetrafluoroethylene-ethylene copolymer) film was placed on the surface of the test piece on the base layer side. Further, on the polyethylene resin layer side surface of the test piece, five wires A and five wires B each at a pitch of 10 mm and an ETFE film were arranged in this order. Thereafter, lamination was performed using a hot roll laminator under conditions of a set temperature of 120° C.
  • N/wire indicates the peel strength when one wire is peeled off.
  • a white tempered glass sheet with a thickness of 3.2 mm was used as the transparent substrate, and an ethylene-vinyl acetate copolymer (EVA) sheet with a thickness of 470 ⁇ m (manufactured by Takiron CI Co., Ltd., Fast Cure EVA) was used, an N-type silicon cell was used as the solar cell element, and an aluminum layer-containing backsheet (VAPE-CW, manufactured by Dainippon Printing Co., Ltd.) was used as the counter substrate.
  • EVAPE-CW aluminum layer-containing backsheet
  • Vacuum lamination was performed under the conditions of 5 minutes, pressing 7.5 minutes, and pressure 100 kPa.
  • the current collecting sheet was arranged so that the surface on the wire side of the current collecting sheet faced the solar cell element side.
  • FIG. 3(b) by arranging the current collector sheets 20 above and below the solar cell elements 31, a solar cell module in which four solar cell elements are connected in series can be used for evaluation. A module was created.
  • the photovoltaic output before and after each test was measured, and the output reduction rate was determined.
  • Module reliability was evaluated based on the following criteria.
  • C The output reduction rate after at least one test is 10% or more.
  • Example 3 As a barrier film having a protective layer and a transparent barrier layer, a barrier film in which a 10 nm thick silicon oxide vapor deposited film was formed on one side of a 12 ⁇ m thick polyethylene terephthalate (PET) film (“Tech Barrier Tech” manufactured by Mitsubishi Chemical Corporation) was used. LX”) was used. In addition, a two-component adhesive consisting of a polycarbonate base agent (KT-0035 manufactured by Rock Paint Co., Ltd.) and an isocyanate curing agent (H-039Z2 manufactured by Rock Paint Co., Ltd.) was used as the adhesive. .
  • PET polyethylene terephthalate
  • H-039Z2 manufactured by Rock Paint Co., Ltd.
  • low density polyethylene (LDPE) ("Sumikasen CE4009” manufactured by Sumitomo Chemical Co., Ltd.) was used as the polyethylene resin.
  • LDPE low density polyethylene
  • PET polyethylene terephthalate film
  • LLD polyethylene terephthalate
  • the adhesive was applied to a thickness of 5 ⁇ m on one side of the transparent substrate, and the adhesive was bonded to the silicon oxide vapor-deposited film side of the barrier film using a dry lamination method. Subsequently, aging was performed at 45° C. for 5 days to cure the adhesive. Next, the adhesive was applied as an anchor to the surface of the barrier film on the protective layer side, and polyethylene resin was extruded to a thickness of 60 ⁇ m to form a sealing layer. Further, the surface of the sealing layer opposite to the barrier film was subjected to corona treatment. Thereby, a film for a current collector sheet having a transparent base material, a second adhesive layer, a transparent barrier layer, a protective layer, an adhesive layer, and a sealing layer in this order was obtained.
  • Example 4 A current collector sheet film was produced in the same manner as in Example 3, except that the barrier film was produced as described below. Thereby, a film for a current collector sheet having a transparent base material, a second adhesive layer, an overcoat layer, a transparent barrier layer, a protective layer, an adhesive layer, and a sealing layer in this order was obtained.
  • a film having a transparent base material and a transparent barrier layer As a film having a transparent base material and a transparent barrier layer, a film (manufactured by Mitsubishi Chemical Corporation) in which a 10 nm thick silicon oxide vapor deposited film (transparent barrier layer) was formed on one side of a 12 ⁇ m thick polyethylene terephthalate (PET) film was used. "Tech Barrier Tech LX”) was used.
  • a resin composition for forming an overcoat layer was prepared. Specifically, Solution B having the following composition was added to Solution A having the following composition and stirred to obtain a resin composition for an overcoat layer by a sol-gel method.
  • ⁇ Liquid B Hydrolyzed liquid> Tetraethyl orthosilicate (TEOS) 21.49 parts by mass Isopropyl alcohol 5.03 parts by mass 0.5N aqueous hydrochloric acid solution 0.69 parts by mass Ion exchange water 29.1 parts by mass
  • TEOS Tetraethyl orthosilicate
  • the resin composition was applied onto the transparent barrier layer of the film, dried by heating at 150°C for 30 seconds, and heat-treated at 200°C for 30 seconds. Thereby, a barrier film having a transparent base material, a transparent barrier layer, and an overcoat layer in this order was obtained.
  • LLD polyethylene terephthalate
  • a two-component adhesive consisting of a polycarbonate base agent (KT-0035 manufactured by Rock Paint Co., Ltd.) and an isocyanate curing agent (H-039Z2 manufactured by Rock Paint Co., Ltd.) was used as the adhesive.
  • LDPE low density polyethylene
  • the adhesive was applied as an anchor to one side of the transparent base material, and the polyethylene resin was extruded to a thickness of 60 ⁇ m to form a sealing layer containing polyethylene resin. Furthermore, the surface of the sealing layer opposite to the transparent base material was subjected to corona treatment. Thereby, a film for a current collector sheet having a transparent base material, an adhesive layer, and a sealing layer in this order was obtained.
  • a 50 ⁇ m thick white PET film (“S-PV8W” manufactured by DuPont), a 7 ⁇ m thick aluminum foil, a 250 ⁇ m thick transparent PET film (“Mylar A S6” manufactured by DuPont), and a 30 ⁇ m thick A back protection sheet A was prepared in which polyethylene films (“SE625NWT02" manufactured by Tamapori Co., Ltd., white LLDPE) were laminated in this order via an adhesive.
  • a barrier film is laminated in this order via an adhesive, and then a weather-resistant top coat layer based on an acrylic resin with a thickness of 5 ⁇ m is formed on the surface on the transparent PET film side.
  • a back protection sheet B was prepared, on which an easily adhesive primer layer with a thickness of 1 ⁇ m was formed.
  • a polyethylene terephthalate (PET) film (“BP” manufactured by DuPont) having a thickness of 152 ⁇ m and having hydrolysis resistance was used.
  • BP polyethylene terephthalate
  • SE625N 30 ⁇ m thick polyethylene film
  • SE625N 30 ⁇ m thick polyethylene film
  • H-039Z2 manufactured by Rock Paint Co., Ltd.
  • a base material layer and an easily adhesive layer were laminated via an adhesive by a dry lamination method. Thereby, a back protection sheet D having a base material layer, a third adhesive layer, and an easy-to-adhesion layer in this order was obtained.
  • a polyethylene terephthalate (PET) film (“BP” manufactured by DuPont) having a thickness of 152 ⁇ m and having hydrolysis resistance was used.
  • PET polyethylene terephthalate
  • a 30 ⁇ m thick polyethylene film (“SE625N” manufactured by Tamapoly Co., Ltd.) was used as an easily adhesive layer.
  • a two-component adhesive consisting of a polycarbonate base agent (KT-0035 manufactured by Rock Paint Co., Ltd.) and an isocyanate curing agent (H-039Z2 manufactured by Rock Paint Co., Ltd.) was used as the adhesive. .
  • the base material layer, the second barrier film, and the easy-to-adhesion layer were each laminated via an adhesive by a dry lamination method. Thereby, a back protection sheet E was obtained which had a base material layer, a third adhesive layer, a second barrier film, a fourth adhesive layer, and an easily adhesive layer in this order.
  • the second barrier film was arranged so that the transparent base material was on the easily adhesive layer side and the overcoat layer was on the base layer side.
  • a test solar cell module was produced using a current collector sheet film and a back protection sheet. Specifically, a 3.2 mm thick white tempered glass plate was used as the transparent substrate, and a 470 ⁇ m thick ethylene-vinyl acetate copolymer (EVA) sheet (Takiron) was used as the first and second sealing materials. Fast Cure EVA) manufactured by CI Corporation was used.
  • EVA ethylene-vinyl acetate copolymer
  • the high temperature and high humidity test was conducted by placing the test solar cell module in an oven set at a temperature of 85°C and a humidity of 85% RH. The coloration of the paper was visually observed.
  • a resin film for a current collector sheet used in a current collector sheet of a solar cell It has a base material layer, an adhesive layer, and a polyethylene resin layer in this order,
  • the base layer contains polyethylene terephthalate resin
  • the polyethylene resin layer has a melt mass flow rate at 190° C. of 4 g/10 minutes or more and 8 g/10 minutes or less
  • a resin film for a current collector sheet which has a heat shrinkage rate of 2.0% or less when held at 150°C for 10 minutes.
  • Film for sheets. [12] The film for a current collector sheet according to any one of [8] to [11], wherein the sealing layer contains a polyolefin resin.
  • the polyolefin resin is a polyethylene resin.
  • the sealing layer has a surface treatment portion on a surface opposite to the adhesive layer.
  • a current collector sheet used for solar cells The resin film for current collector sheet according to any one of [1] to [7], A wire arranged on the surface side of the polyethylene resin layer of the resin film for current collector sheet; A current collecting sheet having.
  • a current collector sheet used in solar cells The film for current collector sheet according to any one of [8] to [14], A wire arranged on the surface side of the sealing layer of the current collector sheet film; A current collecting sheet having.
  • the current collector sheet according to [15] a solar cell element arranged on the surface side of the polyethylene resin layer of the current collector sheet and electrically connected to the wire; A solar cell element with a current collecting sheet.
  • a solar cell comprising, in this order, a transparent substrate, a first encapsulant, the solar cell element with a current collector sheet according to [17], a second encapsulant, and a counter substrate.
  • a solar cell comprising, in this order, a transparent substrate, a first encapsulant, the solar cell element with a current collector sheet according to [18], a second encapsulant, and a back protection sheet.
  • the back protection sheet includes, in order from the second sealing material side, an easily adhesive layer, a barrier film, and a base layer.
  • Base material layer 2 ... Adhesive layer 3
  • Polyethylene resin layer 10, 10A, 10B Resin film for current collector sheet 11... Wire 20

Abstract

The present disclosure provides a resin film (10) for current collector sheets, the resin film (10) being used for a current collector sheet of a solar cell. This resin film (10) for current collector sheets sequentially comprises a base material layer (1), an adhesive layer (2) and a polyethylene resin layer (3) in this order; the base material layer (1) contains a polyethylene terephthalate resin; the melt mass flow rate of the polyethylene resin layer at 190°C is 4 g/10 minutes to 8 g/10 minutes; and the thermal shrinkage after being held at 150°C for 10 minutes is 2.0% or less.

Description

集電シート用樹脂フィルム、集電シート用フィルム、集電シート、集電シート付き太陽電池素子、および太陽電池Resin films for current collector sheets, films for current collector sheets, current collector sheets, solar cell elements with current collector sheets, and solar cells
　本開示は、集電シート用樹脂フィルム、集電シート用フィルム、集電シート、集電シート付き太陽電池素子、および太陽電池に関する。 The present disclosure relates to a resin film for a current collector sheet, a film for a current collector sheet, a current collector sheet, a solar cell element with a current collector sheet, and a solar cell.
　近年、二酸化炭素が原因とされる地球温暖化が世界的に問題となっている。この問題に対し、環境にやさしく、クリーンなエネルギー源として、太陽光エネルギーを利用した太陽電池が注目され、積極的な研究開発が進められている。 In recent years, global warming caused by carbon dioxide has become a worldwide problem. In response to this problem, solar cells that utilize sunlight energy are attracting attention as an environmentally friendly and clean energy source, and active research and development is underway.
　太陽電池は、例えば、複数の太陽電池素子を接続したモジュールの形態で用いられる。太陽電池素子同士を接続する方法としては、例えば、バスパーと称される幅２ｍｍから５ｍｍ程度の帯状の導線を用いて、太陽電池素子同士を接続する方法が従来から用いられている。バスパーを用いた接続方法の場合、太陽電池モジュールにおいて、バスパーが配置された領域では太陽光が物理的に遮断されるため、太陽電子素子への太陽光の入射量が減少してしまうという課題がある。 A solar cell is used, for example, in the form of a module in which a plurality of solar cell elements are connected. As a method for connecting solar cell elements to each other, for example, a method of connecting solar cell elements to each other using a strip-shaped conducting wire with a width of about 2 mm to 5 mm, called a buspar, has been used. In the case of the connection method using buspars, the problem is that sunlight is physically blocked in the area where the buspars are placed in the solar cell module, reducing the amount of sunlight incident on the solar electronic elements. be.
　これに対し、近年、例えば、直径１５０μｍ以上３００μｍ以下程度のワイヤ（細線状の導線）を用いて太陽電池素子同士を接続する、マルチワイヤ接続と称される方法が採用され始めている。マルチワイヤ接続において、ワイヤを太陽電池素子に固定する方法としては、例えば、熱溶着性を有する樹脂フィルムにワイヤを埋め込んで集電シートとし、上記集電シートを太陽電池素子に熱圧着することにより固定する方法が挙げられる（特許文献１および２）。集電シートに用いられる樹脂フィルムは、コネクティングフィルムとも称される。 On the other hand, in recent years, a method called multi-wire connection has begun to be adopted, in which solar cell elements are connected to each other using wires (thin conductive wires) with a diameter of about 150 μm or more and 300 μm or less, for example. In the multi-wire connection, a method for fixing the wires to the solar cell element is, for example, by embedding the wires in a thermofusible resin film to make a current collecting sheet, and then thermocompression bonding the current collecting sheet to the solar cell element. Examples include fixing methods (Patent Documents 1 and 2). The resin film used for the current collector sheet is also called a connecting film.
国際公開第２００４／０２１４５５号International Publication No. 2004/021455 国際公開第２０１７／０７６７３５号International Publication No. 2017/076735 特開２０２０－１７４０６０号公報JP2020-174060A 特開２００２－１３４７７０号公報Japanese Patent Application Publication No. 2002-134770
　マルチワイヤ接続において、熱溶着性を有する樹脂フィルムにワイヤを埋め込んで集電シートとする際には、集電シートを太陽電池素子に熱圧着する前に、ワイヤが樹脂フィルムからはずれないように、ワイヤが樹脂フィルムに安定的に保持される必要がある。また、集電シートを太陽電池素子に熱圧着する際には、樹脂フィルムがワイヤの周囲に回り込み、太陽電池素子に対してワイヤを固定する必要がある。そのため、マルチワイヤ接続に用いられる集電シートの樹脂フィルムには、ワイヤに対する密着性およびワイヤの埋め込み性が求められる。 In multi-wire connection, when wires are embedded in a heat-fusible resin film to form a current collector sheet, before thermocompression bonding the current collector sheet to the solar cell element, make sure that the wires do not come off the resin film. The wire needs to be stably held in the resin film. Furthermore, when thermocompression bonding the current collector sheet to the solar cell element, it is necessary for the resin film to wrap around the wire and fix the wire to the solar cell element. Therefore, the resin film of the current collector sheet used for multi-wire connections is required to have good adhesion to the wires and embeddability of the wires.
　例えば特許文献３には、基材層とワイヤ保持層とを有する太陽電池モジュール用の集電ワイヤ固定フィルムにおいて、ワイヤ保持層の複素粘度を特定範囲に最適化することによって、ワイヤ全体がワイヤ保持層に埋没してしまうことによる通電不良を回避しながら、尚且つ、適度にワイヤ保持力を発揮できる技術が開示されている。 For example, in Patent Document 3, in a current collecting wire fixing film for a solar cell module having a base material layer and a wire holding layer, the entire wire is fixed by optimizing the complex viscosity of the wire holding layer to a specific range. A technique has been disclosed that can exert a suitable wire holding force while avoiding poor conduction due to being buried in the layer.
　しかし、ワイヤの材料によっては、樹脂フィルムのワイヤに対する密着性が十分ではないことがあり、未だ改良の余地がある。 However, depending on the material of the wire, the adhesion of the resin film to the wire may not be sufficient, and there is still room for improvement.
　また、マルチワイヤ接続においては、集電シート付き太陽電池素子と他の構成部材とを熱圧着により一体化して太陽電池モジュールとする際に、樹脂フィルムが熱収縮し、太陽電池素子に対してワイヤの位置がずれてしまうという問題がある。ワイヤの位置ずれが生じると、太陽電池素子とワイヤとの導通が不十分になり、信頼性が低下する。 In addition, in multi-wire connections, when the solar cell element with a current collector sheet and other components are integrated by thermocompression bonding to form a solar cell module, the resin film shrinks due to heat, and the wires are connected to the solar cell element. There is a problem that the position of the image may be shifted. When the wires are misaligned, electrical conduction between the solar cell element and the wires becomes insufficient, resulting in decreased reliability.
　本開示の一実施形態は、上記実情に鑑みてなされたものであり、ワイヤに対する密着性およびワイヤの埋め込み性に優れ、熱寸法安定性にも優れる集電シート用樹脂フィルム、ならびに、これを用いた集電シート、集電シート付き太陽電池素子および太陽電池を提供することを第一の目的とする。 One embodiment of the present disclosure has been made in view of the above circumstances, and provides a resin film for a current collector sheet that has excellent adhesion to wires and wire embedding properties, and excellent thermal dimensional stability, and a resin film using the same. The first object of the present invention is to provide a current collector sheet, a solar cell element with a current collector sheet, and a solar cell.
　ところで、太陽電池は、長期間にわたって屋外で使用されるため、太陽電池を構成する各部材には長期間にわたって屋外における過酷な環境に耐え得る耐久性が求められる。これらの部材のうち、裏面保護シートは、高い耐候性が要求されるとともに、太陽電池素子を水分等から保護するために、高い水蒸気バリア性を有することが求められている。 By the way, since solar cells are used outdoors for a long period of time, each member constituting the solar cell is required to have durability that can withstand the harsh outdoor environment for a long period of time. Among these members, the back protection sheet is required to have high weather resistance, and is also required to have high water vapor barrier properties in order to protect the solar cell element from moisture and the like.
　例えば、太陽電池モジュールを構成する裏面保護シートとしては、耐候性を有する基材に、アルミニウム箔等の金属箔を積層させた裏面保護シートが知られている（特許文献４）。しかし、金属箔を有する裏面保護シートは、太陽電池モジュールに使用した際には、絶縁性が低いために漏電のおそれがある。また、金属箔の端面の絶縁処理が行われているが、生産性が低下し、製造コストが増加する。 For example, as a back protection sheet constituting a solar cell module, a back protection sheet in which metal foil such as aluminum foil is laminated on a weather-resistant base material is known (Patent Document 4). However, when a back protection sheet having metal foil is used in a solar cell module, there is a risk of electrical leakage due to its low insulation properties. In addition, although insulation treatment is performed on the end surfaces of metal foils, productivity decreases and manufacturing costs increase.
　また、裏面保護シートとしては、金属箔の代わりに、樹脂フィルムに無機蒸着膜が形成されたバリアフィルムを有する裏面保護シートも知られている。このような裏面保護シートは、金属箔を使用しなくとも、水蒸気バリア性を発揮できる。しかし、金属箔に匹敵する高い水蒸気バリア性を有するガスバリアフィルムは、非常に高価である。 Furthermore, as a back protection sheet, there is also known a back protection sheet having a barrier film in which an inorganic vapor-deposited film is formed on a resin film instead of a metal foil. Such a back protection sheet can exhibit water vapor barrier properties without using metal foil. However, gas barrier films with high water vapor barrier properties comparable to metal foils are very expensive.
　そこで、マルチワイヤ接続の太陽電池モジュールにおいて、水蒸気バリア性の向上のために、裏面保護シートだけでなく、上記の集電シートに用いられる樹脂フィルムにも、水蒸気バリア性を付与することが考えられる。 Therefore, in order to improve the water vapor barrier properties of multi-wire connected solar cell modules, it is considered that not only the back protection sheet but also the resin film used in the current collector sheet described above may be provided with water vapor barrier properties. .
　本開示の他の実施形態は、上記実情に鑑みてなされたものであり、高いバリア性を有する集電シート用フィルム、ならびに、これを用いた集電シート、集電シート付き太陽電池素子および太陽電池を提供することを第二の目的とする。 Other embodiments of the present disclosure have been made in view of the above circumstances, and provide a current collector sheet film having high barrier properties, a current collector sheet using the same, a solar cell element with a current collector sheet, and a solar cell element with a current collector sheet. The second purpose is to provide batteries.
　本開示の一実施形態は、太陽電池の集電シートに用いられる集電シート用樹脂フィルムであって、基材層と、接着層と、ポリエチレン樹脂層と、をこの順に有し、上記基材層が、ポリエチレンテレフタレート樹脂を含有し、上記ポリエチレン樹脂層の１９０℃におけるメルトマスフローレート（ＭＦＲ）が、４ｇ／１０分以上８ｇ／１０分以下であり、１５０℃で１０分間保持したときの熱収縮率が、２．０％以下である、集電シート用樹脂フィルムを提供する。 One embodiment of the present disclosure is a resin film for a current collector sheet used for a current collector sheet of a solar cell, which includes a base material layer, an adhesive layer, and a polyethylene resin layer in this order, The layer contains a polyethylene terephthalate resin, the melt mass flow rate (MFR) at 190°C of the polyethylene resin layer is 4 g/10 minutes or more and 8 g/10 minutes or less, and heat shrinkage when held at 150° C. for 10 minutes. Provided is a resin film for a current collector sheet having a ratio of 2.0% or less.
　本開示の他の実施形態は、太陽電池の集電シートに用いられる集電シート用フィルムであって、透明基材と、透明バリア層と、接着層と、封止層と、をこの順に有する、集電シート用フィルムを提供する。 Another embodiment of the present disclosure is a film for a current collector sheet used for a current collector sheet of a solar cell, which includes a transparent base material, a transparent barrier layer, an adhesive layer, and a sealing layer in this order. , provides a film for current collector sheets.
　本開示の他の実施形態は、太陽電池に用いられる集電シートであって、上述の集電シート用樹脂フィルムと、上記集電シート用樹脂フィルムの上記ポリエチレン樹脂層の面側に配置されたワイヤとを有する、集電シートを提供する。 Another embodiment of the present disclosure is a current collector sheet used for a solar cell, which includes the above resin film for current collector sheet and the polyethylene resin layer disposed on the surface side of the polyethylene resin layer of the resin film for current collector sheet. A current collecting sheet having a wire is provided.
　本開示の他の実施形態は、太陽電池に用いられる集電シートであって、上述の集電シート用フィルムと、上記集電シート用フィルムの上記封止層の面側に配置されたワイヤとを有する、集電シートを提供する。 Another embodiment of the present disclosure is a current collector sheet used for a solar cell, which includes the above-mentioned current collector sheet film and a wire disposed on the surface side of the sealing layer of the current collector sheet film. Provided is a current collector sheet having the following.
　本開示の他の実施形態は、上述の集電シートと、上記集電シートの上記ポリエチレン樹脂層の面側に配置され、上記ワイヤと電気的に接続された太陽電池素子とを有する、集電シート付き太陽電池素子を提供する。 Another embodiment of the present disclosure is a current collector comprising the above-described current collector sheet and a solar cell element disposed on the surface side of the polyethylene resin layer of the current collector sheet and electrically connected to the wire. A solar cell element with a sheet is provided.
　本開示の他の実施形態は、上述の集電シートと、上記集電シートの上記封止層の面側に配置され、上記ワイヤと電気的に接続された太陽電池素子とを有する、集電シート付き太陽電池素子を提供する。 Another embodiment of the present disclosure is a current collector comprising the above-described current collector sheet and a solar cell element disposed on the surface side of the sealing layer of the current collector sheet and electrically connected to the wire. A solar cell element with a sheet is provided.
　本開示の他の実施形態は、透明基板と、第１封止材と、上述の集電シート付き太陽電池素子と、第２封止材と、対向基板と、をこの順に有する、太陽電池を提供する。 Another embodiment of the present disclosure provides a solar cell having a transparent substrate, a first encapsulant, the above-described solar cell element with a current collector sheet, a second encapsulant, and a counter substrate in this order. provide.
　本開示の他の実施形態は、透明基板と、第１封止材と、上述の集電シート付き太陽電池素子と、第２封止材と、裏面保護シートと、をこの順に有する、太陽電池を提供する。 Another embodiment of the present disclosure provides a solar cell including, in this order, a transparent substrate, a first encapsulant, the above-described solar cell element with a current collector sheet, a second encapsulant, and a back protection sheet. I will provide a.
　本開示の一実施形態における集電シート用樹脂フィルムは、ワイヤに対する密着性およびワイヤの埋め込み性に優れ、熱寸法安定性にも優れるという効果を奏する。 The resin film for a current collector sheet according to an embodiment of the present disclosure has excellent adhesion to wires, excellent wire embedding properties, and excellent thermal dimensional stability.
　また、本開示の他の実施形態は、高いバリア性を有する集電シート用フィルムを提供できる。 Further, other embodiments of the present disclosure can provide a film for current collector sheet having high barrier properties.
本開示における集電シート用樹脂フィルムを例示する概略断面図である。FIG. 1 is a schematic cross-sectional view illustrating a resin film for a current collector sheet in the present disclosure. 本開示における集電シートを例示する概略平面図および断面図である。FIG. 1 is a schematic plan view and a cross-sectional view illustrating a current collecting sheet according to the present disclosure. 本開示における集電シート付き太陽電池素子を例示する概略斜視図および断面図である。FIG. 1 is a schematic perspective view and a cross-sectional view illustrating a solar cell element with a current collector sheet according to the present disclosure. 本開示における集電シート用フィルムを例示する概略断面図である。FIG. 1 is a schematic cross-sectional view illustrating a film for a current collector sheet according to the present disclosure. 本開示における集電シートを例示する概略平面図および断面図である。FIG. 1 is a schematic plan view and a cross-sectional view illustrating a current collecting sheet according to the present disclosure. 本開示における集電シート付き太陽電池素子を例示する概略斜視図および断面図である。FIG. 1 is a schematic perspective view and a cross-sectional view illustrating a solar cell element with a current collector sheet according to the present disclosure. 本開示における集電シート用フィルムを例示する概略断面図である。FIG. 1 is a schematic cross-sectional view illustrating a film for a current collector sheet according to the present disclosure. 本開示における集電シートを例示する概略断面図である。FIG. 1 is a schematic cross-sectional view illustrating a current collector sheet in the present disclosure. 本開示における集電シート付き太陽電池素子を例示する概略断面図である。FIG. 1 is a schematic cross-sectional view illustrating a solar cell element with a current collector sheet according to the present disclosure. 本開示における集電シートを例示する概略断面図である。FIG. 1 is a schematic cross-sectional view illustrating a current collector sheet in the present disclosure. 本開示における太陽電池を例示する概略断面図である。FIG. 1 is a schematic cross-sectional view illustrating a solar cell according to the present disclosure.
　下記に、図面等を参照しながら本開示の実施の形態を説明する。ただし、本開示は多くの異なる態様で実施することが可能であり、下記に例示する実施の形態の記載内容に限定して解釈されるものではない。また、図面は説明をより明確にするため、実際の形態に比べ、各部の幅、厚さ、形状等について模式的に表わされる場合があるが、あくまで一例であって、本開示の解釈を限定するものではない。また、本明細書と各図において、既出の図に関して前述したものと同様の要素には、同一の符号を付して、詳細な説明を適宜省略することがある。 Embodiments of the present disclosure will be described below with reference to the drawings and the like. However, the present disclosure can be implemented in many different ways, and should not be construed as being limited to the description of the embodiments exemplified below. Further, in order to make the explanation clearer, the drawings may schematically represent the width, thickness, shape, etc. of each part compared to the actual form, but this is just an example and does not limit the interpretation of the present disclosure. It's not something you do. In addition, in this specification and each figure, the same elements as those described above with respect to the previously shown figures are denoted by the same reference numerals, and detailed explanations may be omitted as appropriate.
　本明細書において、ある部材の上に他の部材を配置する態様を表現するにあたり、単に「上に」あるいは「下に」と表記する場合、特に断りの無い限りは、ある部材に接するように、直上あるいは直下に他の部材を配置する場合と、ある部材の上方あるいは下方に、さらに別の部材を介して他の部材を配置する場合との両方を含む。また、本明細書において、ある部材の面に他の部材を配置する態様を表現するにあたり、単に「面に」あるいは「面側に」と表記する場合、特に断りの無い限りは、ある部材に接するように、直上あるいは直下に他の部材を配置する場合と、ある部材の上方あるいは下方に、さらに別の部材を介して他の部材を配置する場合との両方を含む。 In this specification, when expressing a mode in which another member is placed on top of a certain member, when it is simply expressed as "above" or "below", unless otherwise specified, it means that the member is in contact with a certain member. This includes both cases in which another member is placed directly above or below a certain member, and cases in which another member is placed above or below a certain member via another member. In addition, in this specification, when expressing a mode in which another member is arranged on the surface of a certain member, when it is simply expressed as "on the surface" or "on the surface side", unless otherwise specified, This includes both a case in which another member is placed directly above or directly below a certain member, and a case in which another member is placed above or below a certain member via another member.
　また、本明細書において、「フィルム」、「シート」、「基板」等の用語は、呼称の相違に基づいて相互に区別されない。 Further, in this specification, terms such as "film", "sheet", "substrate", etc. are not distinguished from each other based on the difference in name.
　以下、本開示における集電シート用樹脂フィルム、集電シート用フィルム、集電シート、集電シート付き太陽電池素子、および太陽電池について、詳細に説明する。 Hereinafter, the resin film for current collecting sheet, the film for current collecting sheet, the current collecting sheet, the solar cell element with current collecting sheet, and the solar cell in the present disclosure will be described in detail.
Ａ．集電シート用樹脂フィルム
　本開示における集電シート用樹脂フィルムは、太陽電池の集電シートに用いられる集電シート用樹脂フィルムであって、基材層と、接着層と、ポリエチレン樹脂層と、をこの順に有し、上記基材層が、ポリエチレンテレフタレート樹脂を含有し、上記ポリエチレン樹脂層の１９０℃におけるメルトマスフローレート（ＭＦＲ）が、４ｇ／１０分以上８ｇ／１０分以下であり、１５０℃で１０分間保持したときの熱収縮率が、２．０％以下である。 A. Resin film for current collector sheet The resin film for current collector sheet in the present disclosure is a resin film for current collector sheet used for a current collector sheet of a solar cell, and includes a base material layer, an adhesive layer, a polyethylene resin layer, in this order, the base layer contains a polyethylene terephthalate resin, the polyethylene resin layer has a melt mass flow rate (MFR) at 190°C of 4 g/10 minutes or more and 8 g/10 minutes or less, and 150°C The heat shrinkage rate when held for 10 minutes is 2.0% or less.
　本開示における集電シート用樹脂フィルムについて図を用いて説明する。図１は、本開示における集電シート用樹脂フィルムを例示する概略断面図である。図１に示すように、集電シート用樹脂フィルム１０は、ポリエチレンテレフタレート樹脂を含有する基材層１と、接着層２と、ポリエチレン樹脂層３とをこの順に有する。ポリエチレン樹脂層３のメルトマスフローレート（ＭＦＲ）は、所定の範囲内である。また、集電シート用樹脂フィルム１０を１５０℃で１０分間保持したときの熱収縮率は、所定の値以下である。 The resin film for a current collector sheet in the present disclosure will be explained using figures. FIG. 1 is a schematic cross-sectional view illustrating a resin film for a current collector sheet according to the present disclosure. As shown in FIG. 1, the resin film 10 for current collector sheet has a base material layer 1 containing polyethylene terephthalate resin, an adhesive layer 2, and a polyethylene resin layer 3 in this order. The melt mass flow rate (MFR) of the polyethylene resin layer 3 is within a predetermined range. Moreover, the heat shrinkage rate of the resin film 10 for current collector sheet when held at 150° C. for 10 minutes is below a predetermined value.
　図２（ａ）、（ｂ）は、本開示における集電シート用樹脂フィルムを有する集電シートを例示する概略平面図および断面図である。図２（ｂ）は、図２（ａ）のＡ－Ａ線断面図である。図２（ａ）、（ｂ）に示すように、集電シート２０は、集電シート用樹脂フィルム１０と、集電シート用樹脂フィルム１０のポリエチレン樹脂層３の面側に配置されたワイヤ１１とを有する。このように、集電シート用樹脂フィルム１０は、ワイヤ１１を支持するために用いられる。なお、図２（ａ）は、集電シート用樹脂フィルムのポリエチレン樹脂層側から集電シートを見た概略平面図を示している。 FIGS. 2(a) and 2(b) are a schematic plan view and a cross-sectional view illustrating a current collecting sheet having a resin film for a current collecting sheet according to the present disclosure. FIG. 2(b) is a cross-sectional view taken along the line AA in FIG. 2(a). As shown in FIGS. 2A and 2B, the current collector sheet 20 includes a resin film 10 for a current collector sheet, and a wire 11 disposed on the surface side of the polyethylene resin layer 3 of the resin film 10 for a current collector sheet. and has. In this way, the resin film 10 for current collector sheet is used to support the wire 11. Note that FIG. 2(a) shows a schematic plan view of the current collecting sheet viewed from the polyethylene resin layer side of the resin film for current collecting sheet.
　図３（ａ）～（ｃ）は、本開示における集電シート用樹脂フィルムを有する集電シートを備える集電シート付き太陽電池素子を例示する概略斜視図および断面図である。図３（ｂ）は、図３（ａ）のＡ－Ａ線断面図であり、図３（ｃ）は、図３（ａ）のＢ－Ｂ線断面図である。図３（ａ）～（ｃ）に示すように、集電シート付き太陽電池素子３０は、集電シート２０と、集電シート２０のポリエチレン樹脂層３の面側に配置され、ワイヤ１１と電気的に接続された太陽電池素子３１とを有する。このように、集電シート用樹脂フィルム１０は、太陽電池素子３１に電気的に接続されたワイヤ１１を固定するために用いられる。なお、図３（ａ）～（ｃ）は、集電シート２０が２枚の集電シート用樹脂フィルム１０を有し、各集電シート用樹脂フィルム１０に太陽電池素子３１が配置されている例を示している。 FIGS. 3(a) to 3(c) are a schematic perspective view and a cross-sectional view illustrating a solar cell element with a current collecting sheet including a current collecting sheet having a resin film for a current collecting sheet according to the present disclosure. FIG. 3(b) is a cross-sectional view taken along line AA in FIG. 3(a), and FIG. 3(c) is a cross-sectional view taken along line BB in FIG. 3(a). As shown in FIGS. 3(a) to 3(c), the solar cell element 30 with a current collector sheet is arranged on the surface side of the current collector sheet 20 and the polyethylene resin layer 3 of the current collector sheet 20, and is connected to the wire 11 and It has a solar cell element 31 which is connected to the solar cell element 31. In this way, the resin film 10 for current collector sheet is used to fix the wire 11 electrically connected to the solar cell element 31. In addition, in FIGS. 3(a) to 3(c), the current collecting sheet 20 has two resin films 10 for current collecting sheets, and a solar cell element 31 is arranged on each resin film 10 for current collecting sheets. An example is shown.
　本開示において、基材層はポリエチレンテレフタレート樹脂を含有する。ここで、基材層に含有されるポリエチレンテレフタレート樹脂は、融点が２６０℃程度であり、耐熱性が高い。また、ポリエチレンテレフタレート樹脂は、フィルム状に成形したときに、良好な剛性が得られる。そのため、ポリエチレンテレフタレート樹脂を含有する基材層により、集電シート用樹脂フィルムに剛性を付与できる。よって、集電シート用樹脂フィルムを有する集電シートを用いて集電シート付き太陽電池素子を製造する場合、熱圧着時に、集電シート用樹脂フィルムによって、ワイヤを太陽電池素子に十分に押し当てることができる。また、本開示においては、ポリエチレン樹脂層のＭＦＲが所定の範囲内であることにより、ポリエチレン樹脂層の、ワイヤに対する密着性およびワイヤの埋め込み性を向上させることができる。したがって、集電シート用樹脂フィルムを有する集電シートにおいては、集電シート用樹脂フィルムによって、太陽電子素子に対してワイヤを良好に固定できる。 In the present disclosure, the base layer contains polyethylene terephthalate resin. Here, the polyethylene terephthalate resin contained in the base material layer has a melting point of about 260° C. and has high heat resistance. Furthermore, polyethylene terephthalate resin provides good rigidity when molded into a film. Therefore, the base material layer containing the polyethylene terephthalate resin can impart rigidity to the resin film for the current collector sheet. Therefore, when manufacturing a solar cell element with a current collector sheet using a current collector sheet having a resin film for the current collector sheet, the wire is sufficiently pressed against the solar cell element by the resin film for the current collector sheet during thermocompression bonding. be able to. Further, in the present disclosure, since the MFR of the polyethylene resin layer is within a predetermined range, the adhesion of the polyethylene resin layer to the wire and the embeddability of the wire can be improved. Therefore, in the current collector sheet having the resin film for the current collector sheet, the wire can be well fixed to the solar electronic element by the resin film for the current collector sheet.
　また、集電シート付き太陽電池素子を太陽電池に用いた場合には、集電シート用樹脂フィルムによって、太陽電子素子に対してワイヤを良好に固定できるため、ワイヤの密着不良による発電効率の低下を抑制できる。 In addition, when a solar cell element with a current collector sheet is used in a solar cell, the wire can be well fixed to the solar electronic element by the resin film for the current collector sheet, resulting in a decrease in power generation efficiency due to poor adhesion of the wire. can be suppressed.
　さらに、太陽電池においては、ポリエチレン樹脂層のＭＦＲが所定の範囲内であることにより、ポリエチレン樹脂層の、太陽電池素子に対する密着性も良好にできる。 Furthermore, in a solar cell, by setting the MFR of the polyethylene resin layer within a predetermined range, the adhesion of the polyethylene resin layer to the solar cell element can also be improved.
　また、本開示においては、上述のように、基材層がポリエチレンテレフタレート樹脂を含有することにより、集電シート用樹脂フィルムは剛性を有することができる。そのため、集電シート用樹脂フィルムの熱収縮を抑えることができる。また、上述のように、ポリエチレン樹脂層のＭＦＲが所定の範囲内であることにより、ポリエチレン樹脂層の、ワイヤに対する密着性、ワイヤの埋め込み性、および太陽電池素子に対する密着性を高めることができる。そのため、ポリエチレン樹脂層の厚さが比較的薄い場合であっても、ワイヤに対する密着性、ワイヤの埋め込み性、および太陽電池素子に対する密着性を確保できる。ポリエチレン樹脂層の厚さが薄いと、集電シート用樹脂フィルムの熱収縮は小さくなる。そのため、ポリエチレン樹脂層のＭＦＲが所定の範囲内であることは、集電シート用樹脂フィルムの熱収縮の抑制にも寄与できる。さらに、本開示における集電シート用樹脂フィルムは、所定の熱収縮率を有するため、熱寸法安定性を向上させることができる。よって、集電シート用樹脂フィルムを有する集電シートを用いて集電シート付き太陽電池素子を製造する場合に、加熱工程時の、太陽電池素子に対するワイヤの位置ずれを抑制できる。また、集電シート付き太陽電池素子を用いて太陽電池を製造する場合に、加熱工程時の、太陽電池素子に対するワイヤの位置ずれを抑制できる。さらに、太陽電池の使用環境において、太陽電池が高温に達した場合であっても、太陽電池素子に対するワイヤの位置ずれを抑制できる。よって、太陽電池の信頼性を向上させることができる。 Furthermore, in the present disclosure, as described above, the resin film for the current collector sheet can have rigidity because the base layer contains the polyethylene terephthalate resin. Therefore, thermal shrinkage of the resin film for current collector sheet can be suppressed. Furthermore, as described above, by setting the MFR of the polyethylene resin layer within a predetermined range, it is possible to improve the adhesion of the polyethylene resin layer to the wire, the embeddability of the wire, and the adhesion to the solar cell element. Therefore, even if the thickness of the polyethylene resin layer is relatively thin, adhesion to the wire, embeddability of the wire, and adhesion to the solar cell element can be ensured. When the thickness of the polyethylene resin layer is thin, the thermal shrinkage of the resin film for the current collector sheet becomes small. Therefore, the fact that the MFR of the polyethylene resin layer is within a predetermined range can also contribute to suppressing thermal shrinkage of the resin film for current collector sheet. Furthermore, since the resin film for a current collector sheet in the present disclosure has a predetermined thermal shrinkage rate, thermal dimensional stability can be improved. Therefore, when manufacturing a solar cell element with a current collecting sheet using a current collecting sheet having a resin film for current collecting sheet, it is possible to suppress the positional shift of the wire with respect to the solar cell element during the heating process. Moreover, when manufacturing a solar cell using a solar cell element with a current collector sheet, it is possible to suppress misalignment of the wire with respect to the solar cell element during the heating process. Furthermore, even if the solar cell reaches a high temperature in the environment in which the solar cell is used, it is possible to suppress misalignment of the wire relative to the solar cell element. Therefore, the reliability of the solar cell can be improved.
　また、本開示における集電シート用樹脂フィルムは、熱寸法安定性に優れるので、集電シート用樹脂フィルムを有する集電シートを用いて集電シート付き太陽電池素子を製造する場合、および、集電シート付き太陽電池素子を用いて太陽電池を製造する場合に、加熱工程時の集電シート用樹脂フィルムの熱収縮を抑え、カール変形を抑制できる。 In addition, since the resin film for a current collector sheet in the present disclosure has excellent thermal dimensional stability, it can be used when manufacturing a solar cell element with a current collector sheet using a current collector sheet having the resin film for a current collector sheet. When manufacturing a solar cell using a solar cell element with an electric sheet, thermal shrinkage of the resin film for the current collector sheet during the heating process can be suppressed, and curl deformation can be suppressed.
　以下、本開示における集電シート用樹脂フィルムの各構成について説明する。 Hereinafter, each structure of the resin film for current collector sheet in the present disclosure will be explained.
Ｉ．集電シート用樹脂フィルムの構成
　本開示における集電シート用樹脂フィルムは、基材層と、接着層と、ポリエチレン樹脂層とをこの順に有する。 I. Configuration of resin film for current collector sheet The resin film for current collector sheet in the present disclosure has a base material layer, an adhesive layer, and a polyethylene resin layer in this order.
１．ポリエチレン樹脂層
　本開示におけるポリエチレン樹脂層は、集電シート用樹脂フィルムを集電シートに用いた場合に、ワイヤを支持する部材である。 1. Polyethylene Resin Layer The polyethylene resin layer in the present disclosure is a member that supports the wire when the resin film for current collector sheet is used as the current collector sheet.
（１）ポリエチレン樹脂層の特性
　ポリエチレン樹脂層の１９０℃におけるメルトマスフローレート（ＭＦＲ）は、４ｇ／１０分以上、８ｇ／１０分以下が好ましく、６ｇ／１０分以上、８ｇ／１０分以下がより好ましい。ポリエチレン樹脂層のＭＦＲが上記範囲内であることにより、ワイヤに対する密着性およびワイヤの埋め込み性を向上させることができる。特に、ポリエチレン樹脂層のＭＦＲが６ｇ／１０分以上であることにより、ワイヤの材料にかかわらず、ワイヤに対する密着性およびワイヤの埋め込み性に優れるポリエチレン樹脂層とすることができる。 (1) Characteristics of the polyethylene resin layer The melt mass flow rate (MFR) at 190°C of the polyethylene resin layer is preferably 4 g/10 minutes or more and 8 g/10 minutes or less, more preferably 6 g/10 minutes or more and 8 g/10 minutes or less. preferable. When the MFR of the polyethylene resin layer is within the above range, the adhesion to the wire and the embeddability of the wire can be improved. In particular, when the MFR of the polyethylene resin layer is 6 g/10 minutes or more, the polyethylene resin layer can have excellent adhesion to the wire and excellent wire embedding properties, regardless of the material of the wire.
　なお、ポリエチレン樹脂層のＭＦＲとは、ポリエチレン樹脂層を構成するポリエチレン樹脂組成物のＭＦＲをいう。ここで、ポリエチレン樹脂層のメルトマスフローレート（ＭＦＲ）は、ＪＩＳ　Ｋ７２１０－１：２０１４のＡ法に準拠して測定する。測定条件は、温度１９０℃、荷重２．１６ｋｇとする。 Note that the MFR of the polyethylene resin layer refers to the MFR of the polyethylene resin composition that constitutes the polyethylene resin layer. Here, the melt mass flow rate (MFR) of the polyethylene resin layer is measured in accordance with method A of JIS K7210-1:2014. The measurement conditions are a temperature of 190° C. and a load of 2.16 kg.
　ポリエチレン樹脂層のＭＦＲは、例えば、ポリエチレン樹脂層に含有されるポリエチレン樹脂の分子量により調整できる。 The MFR of the polyethylene resin layer can be adjusted by, for example, the molecular weight of the polyethylene resin contained in the polyethylene resin layer.
　また、ポリエチレン樹脂層の融点は、所望の熱溶着性を示すことができれば特に限定されない。ポリエチレン樹脂層の融点は、例えば、１００℃以上、１２０℃以下が好ましく、１０５℃以上、１１０℃以下がより好ましい。ポリエチレン樹脂層の融点が高すぎると、集電シートを太陽電池素子に圧着する際の加熱温度を高くする必要があることから、製造コストが増大したり、太陽電池素子が劣化したりする可能性がある。一方、ポリエチレン樹脂層の融点が低すぎると、太陽電池の使用環境において、ポリエチレン樹脂層が融解し、ワイヤを固定することが困難となる可能性がある。 Furthermore, the melting point of the polyethylene resin layer is not particularly limited as long as it can exhibit desired thermal weldability. The melting point of the polyethylene resin layer is, for example, preferably 100°C or higher and 120°C or lower, more preferably 105°C or higher and 110°C or lower. If the melting point of the polyethylene resin layer is too high, it is necessary to increase the heating temperature when press-bonding the current collector sheet to the solar cell element, which may increase manufacturing costs or cause the solar cell element to deteriorate. There is. On the other hand, if the melting point of the polyethylene resin layer is too low, the polyethylene resin layer may melt in the usage environment of the solar cell, making it difficult to fix the wire.
　ここで、ポリエチレン樹脂層の融点は、ＪＩＳ　Ｋ７１２１：２０１２（プラスチックの転移温度測定方法）に準拠し、示差走査熱量分析（ＤＳＣ）により行う。なお、その際、融点ピークが２つ以上存在する場合は、高い温度の方を融点とする。 Here, the melting point of the polyethylene resin layer is determined by differential scanning calorimetry (DSC) in accordance with JIS K7121:2012 (method for measuring transition temperature of plastics). In addition, in that case, when two or more melting point peaks exist, the higher temperature is taken as the melting point.
（２）ポリエチレン樹脂層の材料
（ａ）ポリエチレン樹脂
　ポリエチレン樹脂層は、ポリエチレン樹脂を含有する。ポリエチレン樹脂は、上述のＭＦＲを満たすポリエチレン樹脂層を得ることが可能であれば特に限定されない。ポリエチレン樹脂としては、例えば、高密度ポリエチレン（ＨＤＰＥ）、低密度ポリエチレン（ＬＤＰＥ）、直鎖状低密度ポリエチレン（ＬＬＤＰＥ）、メタロセン系直鎖状低密度ポリエチレン（Ｍ－ＬＬＤＰＥ）、超低密度ポリエチレン（ＶＬＤＰＥ）等が挙げられる。ポリエチレン樹脂は、１種単独で用いてもよく、２種以上を併用してもよい。中でも、柔軟性や加工性が良いことから、低密度ポリエチレン（ＬＤＰＥ）が好ましい。 (2) Material of polyethylene resin layer (a) Polyethylene resin The polyethylene resin layer contains polyethylene resin. The polyethylene resin is not particularly limited as long as it is possible to obtain a polyethylene resin layer that satisfies the above-mentioned MFR. Examples of polyethylene resins include high-density polyethylene (HDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), metallocene-based linear low-density polyethylene (M-LLDPE), and ultra-low density polyethylene ( VLDPE), etc. One type of polyethylene resin may be used alone, or two or more types may be used in combination. Among these, low density polyethylene (LDPE) is preferred because of its good flexibility and workability.
　ポリエチレン樹脂の密度は、特に限定されず、例えば、０．８９０ｇ／ｃｍ３以上０．９３０ｇ／ｃｍ３以下が好ましく、０．９００ｇ／ｃｍ３以上０．９２５ｇ／ｃｍ３以下がより好ましい。ポリエチレン樹脂の密度が上記範囲内であることにより、ポリエチレン樹脂層の柔軟性や加工性を高め、ワイヤに対する密着性やワイヤの埋め込み性を高めることができる。 The density of the polyethylene resin is not particularly limited, and is preferably, for example, 0.890 g/cm 3 or more and 0.930 g/cm 3 or less, more preferably 0.900 g/cm 3 or more and 0.925 g/cm 3 or less. When the density of the polyethylene resin is within the above range, the flexibility and processability of the polyethylene resin layer can be improved, and the adhesion to the wire and the embeddability of the wire can be improved.
　ここで、ポリエチレン樹脂の密度は、ＪＩＳ　Ｋ７１１２：１９９９に準拠したピクノメーター法により測定する。 Here, the density of the polyethylene resin is measured by a pycnometer method based on JIS K7112:1999.
　ポリエチレン樹脂層は、樹脂成分として、ポリエチレン樹脂のみを含有していてもよく、ポリエチレン樹脂に加えて、ポリエチレン樹脂以外の樹脂をさらに含有していてもよい。後者の場合、ポリエチレン樹脂層は、ポリエチレン樹脂を主成分として含有することが好ましい。なお、ポリエチレン樹脂層がポリエチレン樹脂を主成分として含有するとは、全樹脂成分の中でもポリエチレン樹脂の割合が最も多いことをいう。 The polyethylene resin layer may contain only polyethylene resin as a resin component, or may further contain a resin other than polyethylene resin in addition to polyethylene resin. In the latter case, the polyethylene resin layer preferably contains polyethylene resin as a main component. Note that the expression that the polyethylene resin layer contains polyethylene resin as a main component means that the proportion of polyethylene resin is the highest among all resin components.
　ポリエチレン樹脂層中の全樹脂成分に対するポリエチレン樹脂の割合は、例えば、５０質量％以上であり、６０質量％以上であってもよく、７０質量％以上であってもよい。また、上記ポリエチレン樹脂の割合は、例えば、９９質量％以下であり、９５質量％以下であってもよく、９０質量％以下であってもよい。なお、上記ポリエチレン樹脂の割合は、１００質量％であってもよい。 The ratio of polyethylene resin to all resin components in the polyethylene resin layer is, for example, 50% by mass or more, may be 60% by mass or more, or may be 70% by mass or more. Further, the proportion of the polyethylene resin may be, for example, 99% by mass or less, 95% by mass or less, or 90% by mass or less. Note that the proportion of the polyethylene resin may be 100% by mass.
（ｂ）接着性向上剤
　本開示におけるポリエチレン樹脂層は、接着性向上剤を含有していてもよい。接着性向上剤は、ワイヤに対する密着性や太陽電池素子に対する密着性を向上させる成分である。 (b) Adhesiveness Improver The polyethylene resin layer in the present disclosure may contain an adhesiveness improver. The adhesion improver is a component that improves the adhesion to wires and the adhesion to solar cell elements.
　接着性向上剤としては、例えば、シラン変性樹脂、シランカップリング剤等が挙げられる。 Examples of the adhesion improver include silane-modified resins, silane coupling agents, and the like.
（ｉ）シラン変性樹脂
　シラン変性樹脂としては、例えば、シラン変性ポリオレフィン樹脂が挙げられる。シラン変性ポリオレフィン樹脂は、α－オレフィンとエチレン性不飽和シラン化合物との共重合体である。共重合体としては、例えば、ランダム共重合体、交互共重合体、ブロック共重合体、およびグラフト共重合体のいずれであってもよい。中でも、共重合体は、グラフト共重合体であることが好ましく、ポリオレフィンを主鎖とし、エチレン性不飽和シラン化合物が側鎖として重合したグラフト共重合体であることが好ましい。このようなグラフト共重合体は、密着性に寄与するシラノール基の自由度が高くなるため、ワイヤに対する密着性および太陽電池素子に対する密着性を一層向上させることができる。 (i) Silane-modified resin Examples of the silane-modified resin include silane-modified polyolefin resins. The silane-modified polyolefin resin is a copolymer of an α-olefin and an ethylenically unsaturated silane compound. The copolymer may be, for example, a random copolymer, an alternating copolymer, a block copolymer, or a graft copolymer. Among these, the copolymer is preferably a graft copolymer, and is preferably a graft copolymer in which a main chain is a polyolefin and an ethylenically unsaturated silane compound is polymerized as a side chain. In such a graft copolymer, the degree of freedom of the silanol groups that contribute to adhesion is increased, so that the adhesion to the wire and the adhesion to the solar cell element can be further improved.
　シラン変性ポリオレフィン樹脂を構成するα－オレフィンとしては、例えば、エチレン、プロピレン、１－ブテン、イソブチレン、１－ペンテン、２－メチル－１－ブテン、３－メチル－１－ブテン、１－ヘキセン、１－ヘプテン、１－オクテン、１－ノネン、１－デセン等が挙げられる。α－オレフィンは、１種単独で用いてもよく、２種以上を併用してもよい。中でも、ポリエチレンが好ましい。すなわち、シラン変性ポリオレフィン樹脂は、シラン変性ポリエチレン樹脂であることが好ましい。シラン変性ポリエチレン樹脂は、ポリエチレン樹脂層に含まれるポリエチレン樹脂との相溶性が良いからである。 Examples of the α-olefin constituting the silane-modified polyolefin resin include ethylene, propylene, 1-butene, isobutylene, 1-pentene, 2-methyl-1-butene, 3-methyl-1-butene, 1-hexene, -heptene, 1-octene, 1-nonene, 1-decene, etc. One type of α-olefin may be used alone, or two or more types may be used in combination. Among them, polyethylene is preferred. That is, the silane-modified polyolefin resin is preferably a silane-modified polyethylene resin. This is because the silane-modified polyethylene resin has good compatibility with the polyethylene resin contained in the polyethylene resin layer.
　また、シラン変性ポリエチレン樹脂は、主鎖として直鎖状低密度ポリエチレン（ＬＬＤＰＥ）にエチレン性不飽和シラン化合物を側鎖としてグラフト重合させた樹脂であることが好ましい。 Furthermore, the silane-modified polyethylene resin is preferably a resin obtained by graft-polymerizing linear low-density polyethylene (LLDPE) as the main chain with an ethylenically unsaturated silane compound as the side chain.
　上記エチレン性不飽和シラン化合物としては、例えば、ビニルトリメトキシシラン、ビニルトリエトキシシラン、ビニルトリプロポキシシラン、ビニルトリイソプロポキシシラン、ビニルトリブトキシシラン、ビニルトリペンチロキシシラン、ビニルトリフェノキシシラン、ビニルトリベンジルオキシシラン、ビニルトリメチレンジオキシシラン、ビニルトリエチレンジオキシシラン、ビニルプロピオニルオキシシラン、ビニルトリアセトキシシラン、ビニルトリカルボキシシランを挙げることができる。エチレン性不飽和シラン化合物は、１種単独で用いてもよく、２種以上を併用してもよい。 Examples of the ethylenically unsaturated silane compound include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltripropoxysilane, vinyltriisopropoxysilane, vinyltributoxysilane, vinyltripentyloxysilane, vinyltriphenoxysilane, vinyl Tribenzyloxysilane, vinyltrimethylenedioxysilane, vinyltriethylenedioxysilane, vinylpropionyloxysilane, vinyltriacetoxysilane, and vinyltricarboxysilane can be mentioned. One type of ethylenically unsaturated silane compound may be used alone, or two or more types may be used in combination.
　シラン変性ポリオレフィン樹脂は、例えば、特開２００３－４６１０５号公報に記載されている製造方法により得ることができる。 The silane-modified polyolefin resin can be obtained, for example, by the manufacturing method described in JP-A No. 2003-46105.
　シラン変性樹脂は、１種単独で用いてもよく、２種以上を併用してもよい。 The silane-modified resins may be used alone or in combination of two or more.
　ポリエチレン樹脂層中のシラン変性樹脂の含有量は、特に限定されず、例えば、２５質量％以下であってもよく、１５質量％以下であってもよい。 The content of the silane-modified resin in the polyethylene resin layer is not particularly limited, and may be, for example, 25% by mass or less, or 15% by mass or less.
（ｉｉ）シランカップリング剤
　シランカップリング剤としては、一般的な太陽電池の封止材に使用されているシランカップリング剤を用いることができる。シランカップリング剤は、１種単独で用いてもよく、２種以上を併用してもよい。 (ii) Silane coupling agent As the silane coupling agent, a silane coupling agent used in general solar cell encapsulants can be used. The silane coupling agents may be used alone or in combination of two or more.
　ポリエチレン樹脂層中のシランカップリング剤の含有量は、特に限定されず、例えば、５質量％以下であってもよい。 The content of the silane coupling agent in the polyethylene resin layer is not particularly limited, and may be, for example, 5% by mass or less.
（ｃ）他の成分
　ポリエチレン樹脂層は、必要に応じて、例えば、酸化防止剤、アンチブロッキング剤、滑剤等の添加剤を含有してもよい。 (c) Other components The polyethylene resin layer may contain additives such as an antioxidant, an anti-blocking agent, and a lubricant, if necessary.
　ここで、集電シート用樹脂フィルムの各層に含有される各樹脂成分の割合は、例えば、示査走査熱量測定（ＤＳＣ）、赤外分光法（ＩＲ）、核磁気共鳴（ＮＭＲ）で検出されるピーク比等から分析する。 Here, the proportion of each resin component contained in each layer of the resin film for current collector sheet is detected by, for example, differential scanning calorimetry (DSC), infrared spectroscopy (IR), or nuclear magnetic resonance (NMR). Analyze based on peak ratio etc.
（３）その他
　ポリエチレン樹脂層の厚さは、集電シート用樹脂フィルムを集電シートに用いた場合に、ワイヤを支持できれば特に限定されず、ワイヤの太さに応じて適宜選択できる。ポリエチレン樹脂層の厚さは、後述の基材層の厚さよりも厚いことが好ましい。これにより、ワイヤに対する密着性およびワイヤの埋め込み性を高めることができる。具体的には、ポリエチレン樹脂層の厚さは、４０μｍ以上１００μｍ以下が好ましく、４５μｍ以上８０μｍ以下がより好ましい。ポリエチレン樹脂層の厚さが上記範囲内であることにより、ワイヤに対する密着性およびワイヤの埋め込み性を高めることができる。 (3) Others The thickness of the polyethylene resin layer is not particularly limited as long as it can support the wire when the resin film for current collector sheet is used as the current collector sheet, and can be appropriately selected depending on the thickness of the wire. The thickness of the polyethylene resin layer is preferably thicker than the thickness of the base material layer described below. Thereby, the adhesion to the wire and the embeddability of the wire can be improved. Specifically, the thickness of the polyethylene resin layer is preferably 40 μm or more and 100 μm or less, more preferably 45 μm or more and 80 μm or less. When the thickness of the polyethylene resin layer is within the above range, the adhesion to the wire and the embeddability of the wire can be improved.
　ポリエチレン樹脂層の接着層とは反対の面は、表面処理が施されていてもよい。すなわち、ポリエチレン樹脂層は、接着層とは反対の面に表面処理部を有していてもよい。これにより、ワイヤに対する密着性および太陽電池素子に対する密着性を向上させることができる。 The surface of the polyethylene resin layer opposite to the adhesive layer may be subjected to surface treatment. That is, the polyethylene resin layer may have a surface treatment portion on the opposite side to the adhesive layer. Thereby, the adhesion to the wire and the adhesion to the solar cell element can be improved.
　表面処理は、ワイヤに対する密着性や太陽電池素子に対する密着性を高めることが可能な表面処理であれば特に限定されず、例えば、コロナ処理、プラズマ処理、紫外線処理、電子線処理、フレーム処理等が挙げられる。中でも、加工コストやポリエチレン樹脂層へのダメージ軽減の面から、コロナ処理が好ましい。 The surface treatment is not particularly limited as long as it can improve adhesion to wires and solar cell elements, and examples include corona treatment, plasma treatment, ultraviolet treatment, electron beam treatment, flame treatment, etc. Can be mentioned. Among these, corona treatment is preferred from the viewpoint of processing cost and damage reduction to the polyethylene resin layer.
２．基材層
　本開示における基材層は、ポリエチレンテレフタレート樹脂を含有する。基材層は、集電シート用樹脂フィルムに剛性を付与する部材である。 2. Base Material Layer The base material layer in the present disclosure contains polyethylene terephthalate resin. The base material layer is a member that provides rigidity to the resin film for current collector sheet.
　基材層は、必要に応じて、各種添加剤を含有することができる。 The base material layer can contain various additives as necessary.
　基材層の厚さは、特に限定されず、集電シート用樹脂フィルムが用いられる太陽電池の大きさ、用途に応じて適宜選択できる。上述したように、基材層の厚さは、ポリエチレン樹脂層の厚さより薄いことが好ましい。具体的には、基材層の厚さは、１２μｍ以上３８μｍ以下が好ましく、１２μｍ以上２５μｍ以下がより好ましい。基材層の厚さが薄すぎると、十分な剛性が得られない可能性がある。また、基材層の厚さが厚すぎると、剛性が高くなりすぎて、集電シート用樹脂フィルムのワイヤへの追従性が低下する可能性がある。 The thickness of the base layer is not particularly limited, and can be appropriately selected depending on the size and purpose of the solar cell in which the resin film for current collector sheet is used. As mentioned above, the thickness of the base material layer is preferably thinner than the thickness of the polyethylene resin layer. Specifically, the thickness of the base layer is preferably 12 μm or more and 38 μm or less, more preferably 12 μm or more and 25 μm or less. If the thickness of the base material layer is too thin, sufficient rigidity may not be obtained. Moreover, if the thickness of the base material layer is too thick, the rigidity will become too high, and there is a possibility that the followability of the resin film for the current collector sheet to the wire will decrease.
　基材層は、アニール処理が施されていることが好ましい。熱寸法安定性を向上させることができる。これにより、後述の集電シート用樹脂フィルムの熱収縮率を所定の範囲になるように調整しやすくなる。よって、集電シート用樹脂フィルムを有する集電シートを用いて集電シート付き太陽電池を製造する場合、太陽電池素子に対しワイヤを固定するための加熱工程時の、太陽電池素子に対するワイヤの位置ずれを抑制できる。また、集電シート付き太陽電池を用いて太陽電池を製造する場合、各部材を一体化するための加熱工程時の、太陽電池素子に対するワイヤの位置ずれを抑制できる。さらに、太陽電池の使用環境において、太陽電池が高温に達した場合であっても、太陽電池素子に対するワイヤの位置ずれを抑制できる。その結果、太陽電池の信頼性を向上させることができる。 The base material layer is preferably subjected to an annealing treatment. Thermal dimensional stability can be improved. This makes it easier to adjust the heat shrinkage rate of the resin film for current collector sheet, which will be described later, within a predetermined range. Therefore, when manufacturing a solar cell with a current collecting sheet using a current collecting sheet having a resin film for current collecting sheet, the position of the wire relative to the solar cell element during the heating process for fixing the wire to the solar cell element Misalignment can be suppressed. Moreover, when manufacturing a solar cell using a solar cell with a current collector sheet, it is possible to suppress misalignment of the wire with respect to the solar cell element during the heating process for integrating each member. Furthermore, even if the solar cell reaches a high temperature in the environment in which the solar cell is used, it is possible to suppress misalignment of the wire relative to the solar cell element. As a result, the reliability of the solar cell can be improved.
　基材層のアニール処理の温度は、例えば、１２０℃以上２５０℃以下が好ましい。 The temperature of the annealing treatment of the base material layer is preferably, for example, 120° C. or more and 250° C. or less.
３．接着層
　本開示における接着層は、上記の基材層とポリエチレン樹脂層との間に配置され、基材層とポリエチレン樹脂層とを接着するための部材である。 3. Adhesive Layer The adhesive layer in the present disclosure is a member that is disposed between the base layer and the polyethylene resin layer and serves to bond the base layer and the polyethylene resin layer.
　接着層に用いられる接着剤としては、透明性を有し、かつ、上記の基材層とポリエチレン樹脂層とを接着させることが可能な接着剤であれば特に限定されず、一般的なフィルムの貼り合わせに用いられる接着剤を挙げることができる。接着剤としては、例えば、ウレタン系接着剤、アクリル系接着剤、ポリカーボネート系接着剤、フェノール系接着剤等が挙げられる。また、接着剤は、例えば、ドライラミネート用接着剤であってもよく、押し出しラミネート用アンカーコート剤であってもよい。 The adhesive used for the adhesive layer is not particularly limited as long as it is transparent and capable of bonding the base material layer and the polyethylene resin layer, and general film adhesives can be used. Adhesives used for bonding can be mentioned. Examples of the adhesive include urethane adhesive, acrylic adhesive, polycarbonate adhesive, and phenol adhesive. Further, the adhesive may be, for example, an adhesive for dry lamination or an anchor coating agent for extrusion lamination.
　また、接着剤は、耐湿熱性を有することが好ましい。加水分解による接着強度の低下を抑制できる。例えば、接着剤を構成する樹脂成分は、エステル結合を有さないことが好ましい。具体的には、ウレタン系接着剤の場合、主剤がポリカーボネートポリウレタン樹脂であることが好ましい。 Furthermore, it is preferable that the adhesive has heat and humidity resistance. Decrease in adhesive strength due to hydrolysis can be suppressed. For example, it is preferable that the resin component constituting the adhesive does not have an ester bond. Specifically, in the case of a urethane adhesive, it is preferable that the main ingredient is a polycarbonate polyurethane resin.
　接着層の厚さは、透明性を有し、基材層とポリエチレン樹脂層とを接着させることが可能であれば特に限定されず、例えば、０．１μｍ以上１０μｍ以下が好ましい。 The thickness of the adhesive layer is not particularly limited as long as it has transparency and can bond the base material layer and the polyethylene resin layer, and is preferably 0.1 μm or more and 10 μm or less, for example.
４．その他
　本開示における集電シート用樹脂フィルムの厚さは、特に限定されず、集電シートに用いられるワイヤの太さ等に応じて適宜選択できる。集電シート用樹脂フィルムの厚さは、例えば、５０μｍ以上３００μｍ以下であってもよい。集電シート用樹脂フィルムの厚さが薄すぎると、太陽電池素子に対しワイヤを固定するのが困難になる可能性がある。一方、集電シート用樹脂フィルムの厚さが厚すぎると、透明性が低下する可能性がある。 4. Others The thickness of the resin film for a current collector sheet in the present disclosure is not particularly limited, and can be appropriately selected depending on the thickness of the wire used in the current collector sheet. The thickness of the resin film for the current collector sheet may be, for example, 50 μm or more and 300 μm or less. If the thickness of the resin film for current collector sheet is too thin, it may become difficult to fix the wire to the solar cell element. On the other hand, if the thickness of the resin film for the current collector sheet is too thick, the transparency may decrease.
ＩＩ．集電シート用樹脂フィルムの物性
１．熱収縮率
　本開示における集電シート用樹脂フィルムにおいては、１５０℃で１０分間保持したときの熱収縮率が、２．０％以下であり、好ましくは１．５％以下であり、さらに好ましくは１．０％以下である。集電シート用樹脂フィルムの熱収縮率が上記範囲であることにより、熱寸法安定性を向上させることができる。これにより、集電シート用樹脂フィルムを有する集電シートを用いて集電シート付き太陽電池を製造する場合、太陽電池素子に対しワイヤを固定するための加熱工程時の、太陽電池素子に対するワイヤの位置ずれを抑制できる。また、集電シート付き太陽電池を用いて太陽電池を製造する場合、各部材を一体化するための加熱工程時の、太陽電池素子に対するワイヤの位置ずれを抑制できる。さらに、太陽電池の使用環境において、太陽電池が高温に達した場合であっても、太陽電池素子に対するワイヤの位置ずれを抑制できる。その結果、太陽電池の信頼性を向上させることができる。 II. Physical properties of resin film for current collector sheet 1. Heat Shrinkage Rate In the resin film for current collector sheet according to the present disclosure, the heat shrinkage rate when held at 150°C for 10 minutes is 2.0% or less, preferably 1.5% or less, and more preferably It is 1.0% or less. When the heat shrinkage rate of the resin film for current collector sheet is within the above range, thermal dimensional stability can be improved. As a result, when manufacturing a solar cell with a current collecting sheet using a current collecting sheet having a resin film for current collecting sheet, the wire is attached to the solar cell element during the heating process for fixing the wire to the solar cell element. Positional shift can be suppressed. Moreover, when manufacturing a solar cell using a solar cell with a current collector sheet, it is possible to suppress misalignment of the wire with respect to the solar cell element during the heating process for integrating each member. Furthermore, even if the solar cell reaches a high temperature in the environment in which the solar cell is used, it is possible to suppress misalignment of the wire relative to the solar cell element. As a result, the reliability of the solar cell can be improved.
　特に、後述するように、例えば、ワイヤが、Ｂｉ－Ｓｎ系のはんだやＳｎ－Ｉｎ－Ａｇ－Ｂｉ系のはんだで被覆されている場合には、これらのはんだの融点が比較的高いため、上記の加熱工程での加熱温度が高くなる傾向にある。そのため、上記の場合には、上記の集電シート用樹脂フィルムの熱収縮率は、小さいことがより好ましく、具体的には、１．０％以下がより好ましい。 In particular, as will be described later, when the wire is coated with Bi-Sn solder or Sn-In-Ag-Bi solder, the melting points of these solders are relatively high. The heating temperature in the heating process tends to be higher. Therefore, in the above case, the heat shrinkage rate of the resin film for current collector sheet is more preferably small, and specifically, 1.0% or less is more preferable.
　一方、上記熱収縮率の下限は、０％以上であればよい。 On the other hand, the lower limit of the heat shrinkage rate may be 0% or more.
　ここで、上記の集電シート用樹脂フィルムの熱収縮率は、ＭＤ方向の熱収縮率およびＴＤ方向の熱収縮率のうち、大きい熱収縮率をいう。すなわち、集電シート用樹脂フィルムにおいて、ＭＤ方向の熱収縮率およびＴＤ方向の熱収縮率のうち、大きい熱収縮率が、上記範囲となる。 Here, the heat shrinkage rate of the resin film for current collector sheet refers to the larger heat shrinkage rate of the heat shrinkage rate in the MD direction and the heat shrinkage rate in the TD direction. That is, in the resin film for a current collector sheet, the larger heat shrinkage rate of the heat shrinkage rate in the MD direction and the heat shrinkage rate in the TD direction falls within the above range.
　なお、集電シート用樹脂フィルムのＭＤ方向は、通常、集電シート用樹脂フィルムの長手方向である。また、集電シート用樹脂フィルムのＴＤ方向は、通常、集電シート用樹脂フィルムの短手方向である。 Note that the MD direction of the resin film for current collector sheet is usually the longitudinal direction of the resin film for current collector sheet. Moreover, the TD direction of the resin film for current collector sheet is usually the transverse direction of the resin film for current collector sheet.
　また、上記の集電シート用樹脂フィルムの熱収縮率は、例えば、ＡＳＴＭ　Ｄ１２０４に準拠する方法により測定する。 Further, the thermal shrinkage rate of the resin film for the current collector sheet is measured, for example, by a method based on ASTM D1204.
　集電シート用樹脂フィルムの熱収縮率を制御する手法としては、例えば、基材層の熱収縮率を調整する方法が挙げられる。基材層の熱収縮率を調整する方法としては、上述したように、例えば、基材層にアニール処理を施す方法、基材層に含有されるポリエチレンテレフタレート樹脂の結晶性を調整する方法、ポリエチレンテレフタレート樹脂をフィルム状に成形する際の成形方法や成形条件を調整する方法等が挙げられる。成形方法を調整する方法としては、例えば、成形時の応力や歪みを緩和する緩和処理を施す方法が挙げられる。また、成形条件としては、例えば、延伸倍率等が挙げられる。 Examples of methods for controlling the heat shrinkage rate of the resin film for current collector sheets include a method of adjusting the heat shrinkage rate of the base material layer. As mentioned above, methods for adjusting the heat shrinkage rate of the base material layer include, for example, a method of annealing the base material layer, a method of adjusting the crystallinity of the polyethylene terephthalate resin contained in the base material layer, and a method of adjusting the crystallinity of the polyethylene terephthalate resin contained in the base material layer. Examples include a method of adjusting the molding method and molding conditions when molding the terephthalate resin into a film. Examples of methods for adjusting the molding method include a method of performing a relaxation treatment to relieve stress and strain during molding. Furthermore, examples of the molding conditions include the stretching ratio and the like.
２．波長４００ｎｍ以上１２００ｎｍ以下における光線透過率
　本開示における集電シート用樹脂フィルムの波長４００ｎｍ以上１２００ｎｍ以下における光線透過率は、太陽電池素子が発電可能な程度に太陽光を透過させることができる程度であれば特に限定されない。集電シート用樹脂フィルムの波長４００ｎｍ以上１２００ｎｍ以下における光線透過率は、例えば、７５％以上が好ましく、８０％以上がより好ましく、８５％以上がさらに好ましい。上記光線透過率が上記範囲内であることにより、太陽電池素子の光の利用効率を高くできる。 2. Light transmittance at a wavelength of 400 nm or more and 1200 nm or less The light transmittance of the resin film for a current collector sheet in the present disclosure at a wavelength of 400 nm or more and 1200 nm or less is such that sunlight can be transmitted through the solar cell element to the extent that it can generate electricity. There are no particular limitations. The light transmittance of the resin film for current collector sheet at a wavelength of 400 nm or more and 1200 nm or less is preferably 75% or more, more preferably 80% or more, and even more preferably 85% or more. When the light transmittance is within the above range, the light utilization efficiency of the solar cell element can be increased.
　ここで、上記の波長４００ｎｍ以上１２００ｎｍ以下における光線透過率は、波長４００ｎｍ以上１２００ｎｍ以下における光線透過率の平均値である。波長４００ｎｍ以上１２００ｎｍ以下における光線透過率は、ＪＩＳ　Ｋ７３６１  １：１９９７に準拠して測定する。具体的には、波長４００ｎｍ以上１２００ｎｍ以下における光線透過率は、（株）村上色彩技術研究所製のヘイズメーターＨＭ１５０を用いて、測定する。 Here, the above light transmittance at a wavelength of 400 nm or more and 1200 nm or less is an average value of the light transmittance at a wavelength of 400 nm or more and 1200 nm or less. The light transmittance at a wavelength of 400 nm or more and 1200 nm or less is measured in accordance with JIS K7361 1:1997. Specifically, the light transmittance at a wavelength of 400 nm or more and 1200 nm or less is measured using a haze meter HM150 manufactured by Murakami Color Research Institute.
３．ヘイズ
　本開示における集電シート用樹脂フィルムの透明性は、太陽電池素子が発電可能な程度に太陽光を透過させることができる程度であれば特に限定されない。集電シート用樹脂フィルムの透明性は、例えば、ヘイズによって評価できる。集電シート用樹脂フィルムのヘイズは、例えば、１％以上４０％以下であり、５％以上３０％以下であってもよく、１０％以上２０％以下であってもよい。 3. Haze The transparency of the resin film for a current collector sheet in the present disclosure is not particularly limited as long as it can transmit sunlight to the extent that the solar cell element can generate electricity. The transparency of the resin film for current collector sheet can be evaluated by, for example, haze. The haze of the resin film for the current collector sheet is, for example, 1% or more and 40% or less, may be 5% or more and 30% or less, or may be 10% or more and 20% or less.
　ここで、ヘイズは、ＪＩＳ　Ｋ７１３６：２０００に準拠して測定する。ヘイズは、例えば、（株）村上色彩技術研究所製のヘイズメーターＨＭ１５０を用いて、測定する。 Here, haze is measured in accordance with JIS K7136:2000. Haze is measured using, for example, a haze meter HM150 manufactured by Murakami Color Research Institute.
　なお、集電シート用樹脂フィルムのヘイズを測定するに際しては、測定用サンプルを作製し、測定に供する。測定用サンプルは、以下の方法により作製する。まず、集電シート用樹脂フィルムを５０ｍｍ×５０ｍｍにカットし、試験片を作製する。次いで、ＥＴＦＥ（テトラフルオロエチレン－エチレン共重合体）フィルムと試験片とＥＴＦＥフィルムとをこの順に積層し、設定温度１６５℃、真空引き２分、プレス２．５分、圧力１００ｋＰａの条件で真空ラミネートを行う。これは、製膜段階での集電シート用樹脂フィルムの表面の微細な凹凸を排除するためである。続いて、試験片の両面からそれぞれＥＴＦＥフィルムを除去し、測定用サンプルを作製する。 Note that when measuring the haze of the resin film for current collector sheet, a measurement sample is prepared and used for measurement. The sample for measurement is prepared by the following method. First, a resin film for a current collector sheet is cut into a size of 50 mm x 50 mm to prepare a test piece. Next, the ETFE (tetrafluoroethylene-ethylene copolymer) film, the test piece, and the ETFE film were laminated in this order, and vacuum laminated at a set temperature of 165°C, vacuuming for 2 minutes, pressing for 2.5 minutes, and pressure of 100 kPa. I do. This is to eliminate minute irregularities on the surface of the resin film for current collector sheet at the film forming stage. Subsequently, the ETFE film is removed from both sides of the test piece to prepare a measurement sample.
ＩＩＩ．集電シート用樹脂フィルムの製造方法
　本開示における集電シート用樹脂フィルムの製造方法は、基材層と接着層とポリエチレン樹脂層とをこの順に有する集電シート用樹脂フィルムを得ることができれば特に限定されない。例えば、フィルム状の基材層およびポリエチレン樹脂層を用い、ドライラミネート法により、基材層およびポリエチレン樹脂層をドライラミネート用接着剤を介して積層する方法、フィルム状の基材層を用い、押し出しラミネート法により、基材層およびポリエチレン樹脂層を押し出しラミネート用アンカーコート剤を介して積層する方法等が挙げられる。 III. Method for manufacturing a resin film for current collector sheet The method for manufacturing a resin film for current collector sheet in the present disclosure is particularly suitable if a resin film for current collector sheet having a base material layer, an adhesive layer, and a polyethylene resin layer in this order can be obtained. Not limited. For example, a dry lamination method using a film-like base material layer and a polyethylene resin layer, a method in which the base material layer and a polyethylene resin layer are laminated via a dry laminating adhesive, a method using a film-like base material layer, and an extrusion method. Examples of the lamination method include a method in which a base material layer and a polyethylene resin layer are extruded and laminated via an anchor coating agent for lamination.
　フィルム状の基材層およびポリエチレン樹脂層の形成方法としては、例えば、各層を形成するための樹脂組成物を準備し、上記樹脂組成物を溶融成形する方法を挙げることができる。溶融成形法としては、公知の成形法を用いることができ、例えば、射出成形、押出成形、中空成形、圧縮成形、回転成形等を挙げることができる。成形時の温度は、例えば、樹脂組成物の融点以上である。成形時の温度の上限は、樹脂組成物の種類に応じて適宜調整される。 Examples of the method for forming the film-like base material layer and polyethylene resin layer include a method of preparing a resin composition for forming each layer and melt-molding the resin composition. As the melt molding method, a known molding method can be used, and examples thereof include injection molding, extrusion molding, blow molding, compression molding, and rotational molding. The temperature during molding is, for example, higher than the melting point of the resin composition. The upper limit of the temperature during molding is appropriately adjusted depending on the type of resin composition.
Ｂ．集電シート用フィルム
　本開示における集電シート用フィルムは、太陽電池の集電シートに用いられる集電シート用フィルムであって、透明基材と、透明バリア層と、接着層と、封止層と、をこの順に有する。 B. Film for current collector sheet The film for current collector sheet in the present disclosure is a film for current collector sheet used for a current collector sheet of a solar cell, and includes a transparent base material, a transparent barrier layer, an adhesive layer, and a sealing layer. and, in this order.
　本開示における集電シート用フィルムについて図を用いて説明する。図４は、本開示における集電シート用フィルムを例示する概略断面図である。図４に示すように、集電シート用フィルム５０は、透明基材５１と、透明バリア層５２と、接着層５３と、封止層５４とをこの順に有する。図４に示す集電シート用フィルム５０においては、透明基材５１および透明バリア層５２が、バリアフィルム５５を構成している。 The film for current collector sheet in the present disclosure will be explained using figures. FIG. 4 is a schematic cross-sectional view illustrating a film for a current collector sheet according to the present disclosure. As shown in FIG. 4, the current collector sheet film 50 includes a transparent base material 51, a transparent barrier layer 52, an adhesive layer 53, and a sealing layer 54 in this order. In the current collector sheet film 50 shown in FIG. 4, the transparent base material 51 and the transparent barrier layer 52 constitute a barrier film 55.
　図５（ａ）、（ｂ）は、本開示における集電シート用フィルムを有する集電シートを例示する概略平面図および断面図である。図５（ｂ）は、図５（ａ）のＡ－Ａ線断面図である。図５（ａ）、（ｂ）に示すように、集電シート２０は、集電シート用フィルム５０と、集電シート用フィルム５０の封止層５４の面側に配置されたワイヤ１１とを有する。このように、集電シート用フィルム５０は、ワイヤ１１を支持するために用いられる。なお、図５（ａ）は、集電シート用フィルムの封止層側から集電シートを見た概略平面図を示している。 FIGS. 5(a) and 5(b) are a schematic plan view and a cross-sectional view illustrating a current collecting sheet having a current collecting sheet film according to the present disclosure. FIG. 5(b) is a cross-sectional view taken along line AA in FIG. 5(a). As shown in FIGS. 5(a) and 5(b), the current collecting sheet 20 includes a current collecting sheet film 50 and a wire 11 disposed on the surface side of the sealing layer 54 of the current collecting sheet film 50. have In this way, the current collector sheet film 50 is used to support the wire 11. Note that FIG. 5(a) shows a schematic plan view of the current collecting sheet viewed from the sealing layer side of the film for current collecting sheet.
　図６（ａ）～（ｃ）は、本開示における集電シート用フィルムを有する集電シートを備える集電シート付き太陽電池素子を例示する概略斜視図および断面図である。図６（ｂ）は、図６（ａ）のＡ－Ａ線断面図であり、図６（ｃ）は、図６（ａ）のＢ－Ｂ線断面図である。図６（ａ）～（ｃ）に示すように、集電シート付き太陽電池素子３０は、集電シート２０と、集電シート２０の封止層５４の面側に配置され、ワイヤ１１と電気的に接続された太陽電池素子３１とを有する。このように、集電シート用フィルム５０は、太陽電池素子３１に電気的に接続されたワイヤ１１を固定するために用いられる。なお、図６（ａ）～（ｃ）は、集電シート２０が２枚の集電シート用フィルム５０を有し、各集電シート用フィルム５０に太陽電池素子３１が配置されている例を示している。 FIGS. 6(a) to 6(c) are a schematic perspective view and a cross-sectional view illustrating a solar cell element with a current collecting sheet including a current collecting sheet having a current collecting sheet film according to the present disclosure. FIG. 6(b) is a cross-sectional view taken along line AA in FIG. 6(a), and FIG. 6(c) is a cross-sectional view taken along line BB in FIG. 6(a). As shown in FIGS. 6(a) to 6(c), the solar cell element 30 with a current collecting sheet is arranged on the surface side of the current collecting sheet 20 and the sealing layer 54 of the current collecting sheet 20, and is connected to the wire 11 and It has a solar cell element 31 which is connected to the solar cell element 31. In this way, the current collector sheet film 50 is used to fix the wire 11 electrically connected to the solar cell element 31. Note that FIGS. 6(a) to (c) show an example in which the current collecting sheet 20 has two current collecting sheet films 50, and a solar cell element 31 is arranged on each current collecting sheet film 50. It shows.
　本開示における集電シート用フィルムは、透明バリア層を有することにより、バリア性を付与できる。そのため、集電シート用フィルムを有する集電シートを太陽電池に用いた場合には、バリアフィルムを有する集電シート用フィルムと、バリアフィルムを有する裏面保護シートとを組み合わせることで、バリア性を向上させることが可能である。そのため、裏面保護シートに、金属箔を有する裏面保護シートや、高価なガスバリアフィルムを有する裏面保護シートを使用しなくとも、高いバリア性を得ることができる。したがって、生産性を高め、製造コストを削減できる。 The film for current collector sheet in the present disclosure can impart barrier properties by having a transparent barrier layer. Therefore, when a current collector sheet with a current collector sheet film is used in a solar cell, the barrier properties can be improved by combining the current collector sheet film with a barrier film and the back protection sheet with a barrier film. It is possible to do so. Therefore, high barrier properties can be obtained without using a back protection sheet with metal foil or an expensive gas barrier film as the back protection sheet. Therefore, productivity can be increased and manufacturing costs can be reduced.
　また、上述したように、集電シート用フィルムを有する集電シートを太陽電池に用いた場合には、裏面保護シートに、金属箔を有する裏面保護シートを用いなくとも高いバリア性が得られるため、裏面保護シートの絶縁性を高くでき、漏電を抑制できる。したがって、太陽電池の信頼性を高めることができる。 In addition, as mentioned above, when a current collector sheet having a current collector sheet film is used in a solar cell, high barrier properties can be obtained without using a back protective sheet with metal foil as the back protective sheet. , the insulation properties of the back protection sheet can be increased, and electrical leakage can be suppressed. Therefore, the reliability of the solar cell can be improved.
　以下、本開示における集電シート用フィルムの各構成について説明する。 Hereinafter, each structure of the film for current collector sheet in the present disclosure will be explained.
Ｉ．集電シート用フィルムの構成
　本開示における集電シート用フィルムは、透明基材と、透明バリア層と、接着層と、封止層とをこの順に有する。 I. Configuration of film for current collector sheet The film for current collector sheet in the present disclosure includes a transparent base material, a transparent barrier layer, an adhesive layer, and a sealing layer in this order.
１．透明バリア層
　本開示における透明バリア層は、透明基材の一方の面に配置され、透明性を有し、水蒸気や酸素に対してバリア性を有する部材である。また、透明バリア層は、通常、バリアフィルムを構成する部材である。 1. Transparent Barrier Layer The transparent barrier layer in the present disclosure is a member that is disposed on one surface of a transparent base material, has transparency, and has barrier properties against water vapor and oxygen. Further, the transparent barrier layer is usually a member constituting a barrier film.
　透明バリア層の透明性としては、集電シート用フィルムが透明性を有していれば、透明バリア層が透明性を有するということができる。具体的には、後述するように、集電シート用フィルムの波長４００ｎｍ以上１２００ｎｍ以下における光線透過率およびヘイズが所定の範囲であることが好ましい。 As for the transparency of the transparent barrier layer, if the current collector sheet film has transparency, it can be said that the transparent barrier layer has transparency. Specifically, as described later, it is preferable that the light transmittance and haze of the current collector sheet film at a wavelength of 400 nm or more and 1200 nm or less are within a predetermined range.
　また、透明バリア層のバリア性としては、集電シート用フィルムがバリア性を有していれば、透明バリア層がバリア性を有するということができる。具体的には、後述するように、集電シート用フィルムの水蒸気透過度が所定の範囲内であることが好ましい。 Regarding the barrier properties of the transparent barrier layer, if the current collector sheet film has barrier properties, it can be said that the transparent barrier layer has barrier properties. Specifically, as described later, it is preferable that the water vapor permeability of the current collector sheet film is within a predetermined range.
　また、透明バリア層は、絶縁性を有する。これにより、集電シート用フィルムの絶縁性を高めることができる。また、透明バリア層が絶縁性を有することにより、集電シート用フィルムにおいて、透明バリア層の端面に絶縁処理を施す必要がない。そのため、生産性を高め、製造コストを削減できる。 Furthermore, the transparent barrier layer has insulation properties. Thereby, the insulation properties of the current collector sheet film can be improved. Moreover, since the transparent barrier layer has insulation properties, there is no need to perform insulation treatment on the end face of the transparent barrier layer in the current collector sheet film. Therefore, productivity can be increased and manufacturing costs can be reduced.
　透明バリア層は、透明基材の一方の面に形成可能であり、水蒸気や酸素に対してバリア性を有する層であれば特に限定されず、例えば、無機化合物膜、バリア性樹脂膜、有機－無機ハイブリッド膜等が挙げられる。 The transparent barrier layer can be formed on one side of the transparent substrate, and is not particularly limited as long as it has barrier properties against water vapor and oxygen. Examples include inorganic hybrid membranes.
　無機化合物膜に含まれる無機化合物としては、例えば、無機酸化物、無機酸化窒化物、無機窒化物、無機酸化炭化物、無機酸化炭化窒化物等が挙げられる。具体的には、無機化合物膜に含まれる無機化合物としては、ケイ素、アルミニウム、マグネシウム、カルシウム、カリウム、スズ、ナトリウム、チタン、ホウ素、イットリウム、ジルコニウム、セリウム、亜鉛等の酸化物、酸化窒化物、窒化物、酸化炭化物、酸化炭化窒化物等が挙げられる。より具体的には、ＳｉＯｘ等のケイ素酸化物、ＡｌｙＯｚ等のアルミニウム酸化物、マグネシウム酸化物、チタン酸化物、スズ酸化物、ケイ素亜鉛合金酸化物、インジウム合金酸化物、ケイ素窒化物、アルミニウム窒化物、チタン窒化物、酸化窒化ケイ素、酸化ケイ素亜鉛等を挙げることができる。無機化合物は、１種単独で用いてもよく、２種以上を混合して用いてもよい。 Examples of the inorganic compound contained in the inorganic compound film include inorganic oxides, inorganic oxynitrides, inorganic nitrides, inorganic oxycarbides, and inorganic oxycarbonitrides. Specifically, the inorganic compounds contained in the inorganic compound film include oxides, oxynitrides, etc. of silicon, aluminum, magnesium, calcium, potassium, tin, sodium, titanium, boron, yttrium, zirconium, cerium, zinc, etc. Examples include nitrides, oxidized carbides, oxidized carbonitrides, and the like. More specifically, silicon oxides such as SiOx , aluminum oxides such as AlyOz , magnesium oxides, titanium oxides , tin oxides, silicon-zinc alloy oxides, indium alloy oxides, and silicon nitrides. , aluminum nitride, titanium nitride, silicon oxynitride, zinc silicon oxide, and the like. The inorganic compounds may be used alone or in combination of two or more.
　中でも、無機化合物膜に含まれる無機化合物は、コストおよび性能の面から、ケイ素を含む無機化合物であることが好ましく、ＳｉＯｘ等のケイ素酸化物であることがより好ましい。 Among these, the inorganic compound contained in the inorganic compound film is preferably an inorganic compound containing silicon, more preferably a silicon oxide such as SiO x from the viewpoint of cost and performance.
　また、無機化合物に含まれる金属元素は、後述のオーバーコート層に用いられる金属アルコキシド中の金属元素と同じ種類であることが好ましい。透明バリア層とオーバーコート層とが同じ金属元素を有することにより、透明バリア層とオーバーコート層との密着性を向上させることができる。これより、集電シート用フィルムのバリア性を高めることができる。中でも、透明バリア層およびオーバーコート層のいずれもが、ケイ素を含むことが好ましい。 Furthermore, the metal element contained in the inorganic compound is preferably the same type as the metal element in the metal alkoxide used in the overcoat layer described below. When the transparent barrier layer and the overcoat layer have the same metal element, the adhesion between the transparent barrier layer and the overcoat layer can be improved. Thereby, the barrier properties of the current collector sheet film can be improved. Among these, it is preferable that both the transparent barrier layer and the overcoat layer contain silicon.
　バリア性樹脂膜としては、例えば、エチレン－ビニルアルコール共重合体、ポリビニルアルコール、ポリ塩化ビニリデン等を含むバリア性樹脂膜が挙げられる。 Examples of the barrier resin film include barrier resin films containing ethylene-vinyl alcohol copolymer, polyvinyl alcohol, polyvinylidene chloride, and the like.
　透明バリア層は、単層であってもよく、多層であってもよい。多層の場合、各層の組成は、同じであってもよく、異なっていてもよい。 The transparent barrier layer may be a single layer or a multilayer. In the case of multiple layers, the composition of each layer may be the same or different.
　また、透明バリア層は、蒸着膜であってもよく、コーティング等による塗布膜であってもよい。 Further, the transparent barrier layer may be a vapor deposited film, or may be a coated film formed by coating or the like.
　透明バリア層の形成方法は、透明バリア層の材料や種類に応じて適宜選択される。例えば、蒸着法、塗布法、圧着法等が挙げられる。また、透明バリア層がバリア性樹脂膜である場合には、共押出法により、透明基材と透明バリア層とを積層して形成してもよい。 The method for forming the transparent barrier layer is appropriately selected depending on the material and type of the transparent barrier layer. Examples include a vapor deposition method, a coating method, a pressure bonding method, and the like. Furthermore, when the transparent barrier layer is a barrier resin film, it may be formed by laminating the transparent base material and the transparent barrier layer by coextrusion.
　透明バリア層の厚さは、所望のバリア性および透明性を得ることができれば特に限定されず、透明バリア層の種類や構成に応じて適宜設定される。例えば、透明バリア層が蒸着膜である場合、透明バリア層の厚さは、５ｎｍ以上２００ｎｍ以下であってもよく、１０ｎｍ以上１００ｎｍ以下であってもよい。また、例えば、透明バリア層が塗布膜である場合、透明バリア層の厚さは、数μｍ程度であってもよい。また、例えば、透明バリア層がバリア性樹脂膜である場合、透明バリア層の厚さは、数十μｍ程度であってもよい。透明バリア層の厚さが薄すぎると、十分なバリア性が得られない可能性がある。また、透明バリア層の厚さが厚すぎると、クラック等が発生しやすくなる可能性がある。 The thickness of the transparent barrier layer is not particularly limited as long as desired barrier properties and transparency can be obtained, and is appropriately set depending on the type and configuration of the transparent barrier layer. For example, when the transparent barrier layer is a vapor deposited film, the thickness of the transparent barrier layer may be 5 nm or more and 200 nm or less, or 10 nm or more and 100 nm or less. Further, for example, when the transparent barrier layer is a coating film, the thickness of the transparent barrier layer may be about several μm. Further, for example, when the transparent barrier layer is a barrier resin film, the thickness of the transparent barrier layer may be about several tens of μm. If the thickness of the transparent barrier layer is too thin, sufficient barrier properties may not be obtained. Furthermore, if the transparent barrier layer is too thick, cracks and the like may easily occur.
　また、本開示における集電シート用フィルムは、バリア層として、金属層を有さないことが好ましい。金属層は、通常、導電性を有する。集電シート用フィルムが、導電性を有するバリア層を有さないことにより、絶縁性を高めることができる。金属層は、金属または合金からなる層である。金属層は、例えば、金属箔であってもよく、蒸着膜であってもよい。なお、集電シート用フィルムは、通常、透明性を有することから、金属箔を有さない。 Moreover, it is preferable that the film for a current collector sheet in the present disclosure does not have a metal layer as a barrier layer. The metal layer usually has electrical conductivity. Since the current collector sheet film does not have a barrier layer having conductivity, insulation properties can be improved. The metal layer is a layer made of metal or an alloy. The metal layer may be, for example, a metal foil or a vapor deposited film. Note that the current collector sheet film usually does not have metal foil because it has transparency.
２．透明基材
　本開示における透明基材は、例えば、上記透明バリア層を支持する部材である。 2. Transparent Substrate The transparent substrate in the present disclosure is, for example, a member that supports the transparent barrier layer.
　透明基材の透明性としては、上記透明バリア層と同様に、集電シート用フィルムが透明性を有していれば、透明基材が透明性を有するということができる。 Regarding the transparency of the transparent base material, it can be said that the transparent base material has transparency if the current collector sheet film has transparency, similar to the above-mentioned transparent barrier layer.
　また、透明基材は、耐熱性を有することが好ましい。具体的には、透明基材の融点は、２００℃以上が好ましく、２５０℃以上が好ましい。 Moreover, it is preferable that the transparent base material has heat resistance. Specifically, the melting point of the transparent base material is preferably 200°C or higher, and preferably 250°C or higher.
　ここで、透明基材の融点の測定方法は、上述の集電シート用樹脂フィルムにおけるポリエチレン樹脂層の融点の測定方法と同様である。 Here, the method for measuring the melting point of the transparent substrate is the same as the method for measuring the melting point of the polyethylene resin layer in the resin film for current collector sheet described above.
　透明基材は、透明性および耐熱性を有し、上記透明バリア層を支持できれば特に限定されない。中でも、透明基材は、上記融点を有する熱可塑性樹脂を含む、樹脂フィルムであることが好ましい。上記融点を有する熱可塑性樹脂としては、例えば、ポリエチレンテレフタレート（ＰＥＴ）、ポリエチレンナフタレート（ＰＥＮ）、ポリブチレンテレフタレート（ＰＢＴ）等が挙げられる。特に、耐熱性、透明性、耐薬品性、耐水性、寸法安定性、コスト等の観点から、ポリエチレンテレフタレート（ＰＥＴ）が好ましい。 The transparent base material is not particularly limited as long as it has transparency and heat resistance and can support the transparent barrier layer. Among these, the transparent base material is preferably a resin film containing a thermoplastic resin having the above melting point. Examples of the thermoplastic resin having the above melting point include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), and the like. In particular, polyethylene terephthalate (PET) is preferred from the viewpoints of heat resistance, transparency, chemical resistance, water resistance, dimensional stability, cost, and the like.
　透明基材は、必要に応じて、種々の添加剤を含むことができる。添加剤としては、例えば、滑剤、架橋剤、酸化防止剤、光安定化剤、充填剤、滑剤、強化繊維、補強剤、帯電防止剤、難燃剤、耐炎剤、発泡剤、防カビ剤、改質用樹脂等を挙げることができる。これらの添加剤の含有量は、特に限定されず、その目的に応じて適宜調整される。 The transparent base material can contain various additives as necessary. Examples of additives include lubricants, crosslinking agents, antioxidants, light stabilizers, fillers, lubricants, reinforcing fibers, reinforcing agents, antistatic agents, flame retardants, flame retardants, foaming agents, antifungal agents, and modifiers. Examples include resins for quality. The content of these additives is not particularly limited, and is appropriately adjusted depending on the purpose.
　透明基材は、未延伸の樹脂フィルムであってもよく、一軸または二軸延伸された樹脂フィルムであってもよい。 The transparent base material may be an unstretched resin film, or may be a uniaxially or biaxially stretched resin film.
　透明基材の厚さは、上記透明バリア層を支持することが可能な厚さであれば特に限定されず、集電シート用フィルムが用いられる太陽電池の大きさ、用途に応じて適宜選択できる。中でも、後述するように、透明基材の厚さは、封止層の厚さより薄いことが好ましい。具体的には、透明基材の厚さは、１２μｍ以上３８μｍ以下が好ましく、１２μｍ以上２５μｍ以下がより好ましい。透明基材の厚さが薄すぎると、バリア層を支持するのが困難になる可能性がある。また、透明基材の厚さが厚すぎると、剛性が高くなりすぎて、集電シート用フィルムのワイヤへの追従性が低下する可能性がある。 The thickness of the transparent base material is not particularly limited as long as it can support the transparent barrier layer, and can be appropriately selected depending on the size and purpose of the solar cell in which the current collector sheet film is used. . Among these, as described below, the thickness of the transparent base material is preferably thinner than the thickness of the sealing layer. Specifically, the thickness of the transparent base material is preferably 12 μm or more and 38 μm or less, more preferably 12 μm or more and 25 μm or less. If the thickness of the transparent substrate is too thin, it may be difficult to support the barrier layer. Moreover, if the thickness of the transparent base material is too thick, the rigidity will become too high, and the followability of the current collector sheet film to the wire may be reduced.
　透明基材および透明バリア層がバリアフィルムを構成している場合、透明基材の透明バリア層側の面には、透明バリア層との密着性向上のために、表面処理が施されていてもよい。 When the transparent base material and the transparent barrier layer constitute a barrier film, the surface of the transparent base material on the transparent barrier layer side may be surface-treated to improve adhesion with the transparent barrier layer. good.
　また、後述するように、透明バリア層と接着層との間に保護層が配置されており、保護層が樹脂フィルムであり、保護層および透明バリア層がバリアフィルムを構成している場合、例えば、バリアフィルムの透明バリア層上に第２の接着層を介して透明基材を積層できる。この場合、ドライラミネート法が好ましく用いられる。ドライラミネート法の場合、積層時に、透明バリア層にせん断がかかるのを抑制できる。 Furthermore, as will be described later, when a protective layer is disposed between the transparent barrier layer and the adhesive layer, the protective layer is a resin film, and the protective layer and the transparent barrier layer constitute a barrier film, for example, , a transparent substrate can be laminated on the transparent barrier layer of the barrier film via a second adhesive layer. In this case, a dry lamination method is preferably used. In the case of dry lamination, it is possible to suppress shearing of the transparent barrier layer during lamination.
３．封止層
　本開示における封止層は、熱溶着性を有し、集電シート用フィルムを集電シートに用いた場合に、ワイヤを支持する部材である。 3. Sealing Layer The sealing layer in the present disclosure has thermal weldability and is a member that supports the wire when the current collector sheet film is used as the current collector sheet.
（１）封止層の材料
　封止層に含まれる樹脂は、通常、熱溶着性を有する樹脂である。また、封止層に含まれる樹脂は、集電シートを太陽電池素子に熱圧着した際にワイヤの周囲に回りこむ性質を有することが好ましい。以下、上述の性質をワイヤの埋め込み性と称して説明する場合がある。熱溶着性およびワイヤの埋め込み性を有する樹脂としては、例えば、熱可塑性樹脂を挙げることができる。中でも、透明性の観点から、熱可塑性樹脂は、ポリオレフィン樹脂、アイオノマー樹脂であることが好ましく、ポリオレフィン樹脂であることがより好ましい。以下、ポリオレフィン樹脂の詳細を説明する。 (1) Material of the sealing layer The resin contained in the sealing layer is usually a resin that has thermal weldability. Further, the resin contained in the sealing layer preferably has a property of wrapping around the wire when the current collecting sheet is thermocompression bonded to the solar cell element. Hereinafter, the above-mentioned property may be referred to as wire embeddability. Examples of resins having heat-weldability and wire embedding properties include thermoplastic resins. Among them, from the viewpoint of transparency, the thermoplastic resin is preferably a polyolefin resin or an ionomer resin, and more preferably a polyolefin resin. The details of the polyolefin resin will be explained below.
（ａ）ポリオレフィン樹脂
　封止層に用いられるポリオレフィン樹脂の融点は、所望の熱溶着性およびワイヤの埋め込み性を示すことができれば特に限定されない。ポリオレフィン樹脂の融点は、例えば、１２５℃以下であり、１２０℃以下であってもよく、１１０℃以下であってもよい。また、ポリオレフィン樹脂の融点は、例えば、８０℃以上である。ポリオレフィン樹脂の融点が高すぎる場合は、集電シートを太陽電池素子に熱圧着する際の温度を高くする必要があることから、製造コストが増大したり、太陽電池素子が劣化したりする可能性がある。一方、ポリオレフィン樹脂の融点が低すぎる場合は、太陽電池の使用環境において、封止層が融解し、ワイヤを固定することが困難となる可能性がある。 (a) Polyolefin Resin The melting point of the polyolefin resin used for the sealing layer is not particularly limited as long as it can exhibit desired thermal weldability and wire embedding properties. The melting point of the polyolefin resin is, for example, 125°C or lower, may be 120°C or lower, or may be 110°C or lower. Further, the melting point of the polyolefin resin is, for example, 80° C. or higher. If the melting point of the polyolefin resin is too high, it is necessary to raise the temperature when thermocompression bonding the current collector sheet to the solar cell element, which may increase manufacturing costs or cause the solar cell element to deteriorate. There is. On the other hand, if the melting point of the polyolefin resin is too low, the sealing layer may melt in the usage environment of the solar cell, making it difficult to fix the wire.
　ここで、ポリオレフィン樹脂の融点の測定方法は、上述の集電シート用樹脂フィルムにおけるポリエチレン樹脂層の融点の測定方法と同様である。 Here, the method for measuring the melting point of the polyolefin resin is the same as the method for measuring the melting point of the polyethylene resin layer in the resin film for current collector sheet described above.
　中でも、ポリオレフィン樹脂は、ポリエチレン樹脂、ポリプロピレン樹脂であることが好ましく、ポリエチレン樹脂であることがより好ましい。ワイヤの埋め込み性に優れるためである。 Among these, the polyolefin resin is preferably a polyethylene resin or a polypropylene resin, and more preferably a polyethylene resin. This is because wire embedding is excellent.
　ポリエチレン樹脂の種類およびの密度は、上述の集電シート用樹脂フィルムにおけるポリエチレン樹脂層に用いられるポリエチレン樹脂の種類およびの密度と同様である。 The type and density of the polyethylene resin are the same as the type and density of the polyethylene resin used in the polyethylene resin layer in the resin film for current collector sheet described above.
　封止層は、樹脂成分として、ポリオレフィン樹脂のみを含有していてもよく、ポリオレフィン樹脂に加えて、ポリオレフィン樹脂以外の樹脂をさらに含有していてもよい。後者の場合、封止層は、ポリオレフィン樹脂を主成分として含有することが好ましい。なお、封止層がポリオレフィン樹脂を主成分として含有するとは、全樹脂成分の中でもポリオレフィン樹脂の割合が最も多いことをいう。 The sealing layer may contain only a polyolefin resin as a resin component, or may further contain a resin other than the polyolefin resin in addition to the polyolefin resin. In the latter case, the sealing layer preferably contains polyolefin resin as a main component. Note that the expression that the sealing layer contains polyolefin resin as a main component means that the proportion of polyolefin resin is the highest among all resin components.
　封止層中の全樹脂成分に対するポリオレフィン樹脂の割合は、例えば、５０質量％以上であり、６０質量％以上であってもよく、７０質量％以上であってもよい。また、上記ポリオレフィン樹脂の割合は、例えば、９９質量％以下であり、９５質量％以下であってもよく、９０質量％以下であってもよい。なお、上記ポリオレフィン樹脂の割合は、１００質量％であってもよい。 The proportion of the polyolefin resin to all resin components in the sealing layer is, for example, 50% by mass or more, may be 60% by mass or more, or may be 70% by mass or more. Further, the proportion of the polyolefin resin may be, for example, 99% by mass or less, 95% by mass or less, or 90% by mass or less. Note that the proportion of the polyolefin resin may be 100% by mass.
（ｂ）接着性向上剤
　本開示における封止層は、接着性向上剤を含有していてもよい。接着性向上剤は、上述の集電シート用樹脂フィルムにおけるポリエチレン樹脂層に用いられる接着性向上剤と同様である。 (b) Adhesiveness Improver The sealing layer in the present disclosure may contain an adhesiveness improver. The adhesion improver is the same as the adhesion improver used for the polyethylene resin layer in the resin film for current collector sheet described above.
（ｃ）他の成分
　封止層に用いられる他の成分は、上述の集電シート用樹脂フィルムにおけるポリエチレン樹脂層に用いられる他の成分と同様である。 (c) Other components Other components used in the sealing layer are the same as those used in the polyethylene resin layer in the resin film for current collector sheet described above.
（２）その他
　封止層の厚さは、集電シート用フィルムを集電シートに用いた場合に、ワイヤを支持できれば特に限定されず、ワイヤの太さに応じて適宜選択できる。封止層の厚さは、上記透明基材の厚さよりも厚いことが好ましく、また、後述の保護層の厚さよりも厚いことが好ましい。これにより、ワイヤに対する密着性およびワイヤの埋め込み性を高めることができる。具体的には、封止層の厚さは、上述の集電シート用樹脂フィルムにおけるポリエチレン樹脂層の厚さと同様である。 (2) Others The thickness of the sealing layer is not particularly limited as long as it can support the wire when the current collector sheet film is used as the current collector sheet, and can be appropriately selected depending on the thickness of the wire. The thickness of the sealing layer is preferably thicker than the thickness of the transparent base material, and also preferably thicker than the thickness of the protective layer described below. Thereby, the adhesion to the wire and the embeddability of the wire can be improved. Specifically, the thickness of the sealing layer is the same as the thickness of the polyethylene resin layer in the resin film for current collector sheet described above.
　封止層の接着層とは反対の面は、表面処理が施されていてもよい。すなわち、封止層は、接着層とは反対の面に表面処理部を有していてもよい。これにより、ワイヤに対する密着性および太陽電池素子に対する密着性を向上させることができる。表面処理は、上述の集電シート用樹脂フィルムにおけるポリエチレン樹脂層に施される表面処理と同様である。 The surface of the sealing layer opposite to the adhesive layer may be subjected to surface treatment. That is, the sealing layer may have a surface treatment portion on the opposite side to the adhesive layer. Thereby, the adhesion to the wire and the adhesion to the solar cell element can be improved. The surface treatment is similar to the surface treatment applied to the polyethylene resin layer in the resin film for current collector sheet described above.
４．接着層
　本開示における接着層は、上記の透明バリア層を有するバリアフィルムと、封止層との間に配置され、バリアフィルムと封止層とを接着するための部材である。 4. Adhesive Layer The adhesive layer in the present disclosure is a member that is disposed between the barrier film having the transparent barrier layer described above and the sealing layer and for bonding the barrier film and the sealing layer.
　接着層に用いられる接着剤は、上述の集電シート用樹脂フィルムにおける接着層に用いられる接着剤と同様である。 The adhesive used for the adhesive layer is the same as the adhesive used for the adhesive layer in the resin film for current collector sheet described above.
　接着層の厚さは、透明性を有し、バリアフィルムと封止層とを接着させることが可能であれば特に限定されず、例えば、０．１μｍ以上１０μｍ以下が好ましい。 The thickness of the adhesive layer is not particularly limited as long as it has transparency and can bond the barrier film and the sealing layer, and is preferably 0.1 μm or more and 10 μm or less, for example.
５．保護層
　本開示における集電シート用フィルムは、例えば図７（ａ）、（ｂ）に示すように、透明バリア層５２と接着層５３との間に保護層５６を有していてもよい。この場合、例えば図７（ａ）に示すように、透明基材５１および透明バリア層５２がバリアフィルム５５を構成していてもよく、図７（ｂ）に示すように、保護層５６および透明バリア層５２がバリアフィルム５５を構成していてもよい。保護層は、上記透明バリア層を保護する部材である。透明バリア層を有するバリアフィルムと封止層とを接着層を介して積層する際に、保護層によって、透明バリア層を保護できる。また、集電シート用フィルムを有する集電シートを用いて集電シート付き太陽電池素子や太陽電池を製造する場合に、保護層によって、ワイヤが透明バリア層に接触するのを抑制できる。これにより、ワイヤが透明バリア層に接触することによって、透明バリア層にクラック等が発生し、バリア性が低下するのを抑制できる。 5. Protective Layer The film for current collector sheet in the present disclosure may have a protective layer 56 between the transparent barrier layer 52 and the adhesive layer 53, as shown in FIGS. 7(a) and 7(b), for example. In this case, for example, as shown in FIG. 7(a), a transparent base material 51 and a transparent barrier layer 52 may constitute a barrier film 55, and as shown in FIG. 7(b), a protective layer 56 and a transparent The barrier layer 52 may constitute the barrier film 55. The protective layer is a member that protects the transparent barrier layer. When a barrier film having a transparent barrier layer and a sealing layer are laminated via an adhesive layer, the transparent barrier layer can be protected by the protective layer. Moreover, when manufacturing a solar cell element with a current collecting sheet or a solar cell using a current collecting sheet having a current collecting sheet film, the protective layer can suppress the wires from coming into contact with the transparent barrier layer. Thereby, it is possible to suppress the generation of cracks and the like in the transparent barrier layer due to the wire coming into contact with the transparent barrier layer, and the deterioration of the barrier properties.
　中でも、押し出しラミネート法により、上記のバリアフィルム上に接着層を介して封止層を積層する場合には、透明バリア層と接着層との間に保護層が配置されていることが好ましい。押し出しラミネートの際には、透明バリア層にせん断がかかることによって、透明バリア層のバリア性が低下する可能性がある。そのため、押し出しラミネート時に、保護層によって透明バリア層を保護でき、透明バリア層のバリア性の低下を抑制できる。 Among these, when a sealing layer is laminated on the barrier film via an adhesive layer by extrusion lamination, a protective layer is preferably disposed between the transparent barrier layer and the adhesive layer. During extrusion lamination, shearing is applied to the transparent barrier layer, which may reduce the barrier properties of the transparent barrier layer. Therefore, during extrusion lamination, the transparent barrier layer can be protected by the protective layer, and deterioration of the barrier properties of the transparent barrier layer can be suppressed.
　保護層は、上記透明バリア層を保護できれば特に限定されない。保護層の材料としては、例えば、樹脂が挙げられる。樹脂としては、例えば、ポリオレフィン樹脂、ポリエステル樹脂、環状ポリオレフィン樹脂、ポリスチレン樹脂、アクリロニトリル－スチレン共重合体（ＡＳ樹脂）、アクリロニトリル－ブタジエン－スチレン共重合体（ＡＢＳ樹脂）、ポリ（メタ）アクリル樹脂、ポリカーボネート樹脂、ポリビニルアルコール系樹脂、ポリアミド樹脂、ポリイミド樹脂、ポリウレタン樹脂、アセタール樹脂、セルロース樹脂等を挙げることができる。ポリオレフィン樹脂としては、ポリエチレン、ポリプロピレン等が挙げられる。ポリエステル樹脂としては、ポリエチレンテレフタレート（ＰＥＴ）、ポリエチレンナフタレート（ＰＥＮ）、ポリブチレンテレフタレート（ＰＢＴ）等が挙げられる。ポリビニルアルコール系樹脂としては、ポリビニルアルコール（ＰＶＡ）樹脂、エチレン－ビニルアルコール共重合体（ＥＶＯＨ）樹脂等が挙げられる。ポリアミド樹脂としては、各種のナイロンが挙げられる。 The protective layer is not particularly limited as long as it can protect the transparent barrier layer. Examples of the material for the protective layer include resin. Examples of the resin include polyolefin resin, polyester resin, cyclic polyolefin resin, polystyrene resin, acrylonitrile-styrene copolymer (AS resin), acrylonitrile-butadiene-styrene copolymer (ABS resin), poly(meth)acrylic resin, Examples include polycarbonate resin, polyvinyl alcohol resin, polyamide resin, polyimide resin, polyurethane resin, acetal resin, and cellulose resin. Examples of polyolefin resins include polyethylene and polypropylene. Examples of the polyester resin include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), and the like. Examples of the polyvinyl alcohol resin include polyvinyl alcohol (PVA) resin, ethylene-vinyl alcohol copolymer (EVOH) resin, and the like. Examples of the polyamide resin include various types of nylon.
　中でも、耐熱性、透明性、耐薬品性、耐水性、寸法安定性等の観点から、ポリエチレンテレフタレート（ＰＥＴ）、ポリエチレンナフタレート（ＰＥＮ）、ポリブチレンテレフタレート（ＰＢＴ）等のポリエステル樹脂が好ましい。特に、汎用性およびコストの観点から、ポリエチレンテレフタレート（ＰＥＴ）が好ましい。 Among these, polyester resins such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polybutylene terephthalate (PBT) are preferred from the viewpoint of heat resistance, transparency, chemical resistance, water resistance, dimensional stability, etc. In particular, from the viewpoint of versatility and cost, polyethylene terephthalate (PET) is preferred.
　保護層は、必要に応じて、種々の添加剤を含むことができる。添加剤については、上記透明基材に用いられる添加剤と同様である。これらの添加剤の含有量は、特に限定されず、その目的に応じて適宜調整される。 The protective layer can contain various additives as necessary. The additives are the same as those used for the transparent base material. The content of these additives is not particularly limited, and is appropriately adjusted depending on the purpose.
　保護層は、樹脂フィルムであってもよく、コーティング等による塗布膜であってもよい。 The protective layer may be a resin film, or may be a coating film such as coating.
　保護層が樹脂フィルムである場合、未延伸の樹脂フィルムであってもよく、一軸または二軸延伸された樹脂フィルムであってもよい。 When the protective layer is a resin film, it may be an unstretched resin film or a uniaxially or biaxially stretched resin film.
　保護層の厚さは、特に限定されず、集電シート用フィルムが用いられる太陽電池の大きさ、用途に応じて適宜選択できる。上述したように、保護層の厚さは、封止層の厚さより薄いことが好ましい。具体的には、保護層の厚さは、１２μｍ以上３８μｍ以下が好ましい。保護層の厚さが薄すぎると、透明バリア層を十分に保護することが困難になる可能性がある。また、保護層の厚さが厚すぎると、剛性が高くなりすぎて、集電シート用フィルムのワイヤへの追従性が低下する可能性がある。 The thickness of the protective layer is not particularly limited, and can be appropriately selected depending on the size and purpose of the solar cell in which the current collector sheet film is used. As mentioned above, the thickness of the protective layer is preferably thinner than the thickness of the sealing layer. Specifically, the thickness of the protective layer is preferably 12 μm or more and 38 μm or less. If the thickness of the protective layer is too thin, it may be difficult to adequately protect the transparent barrier layer. Moreover, if the thickness of the protective layer is too thick, the rigidity will become too high, and the followability of the current collector sheet film to the wire may deteriorate.
　保護層が樹脂フィルムであり、バリアフィルムが透明基材および透明バリア層を有する場合、透明バリア層上に保護層を配置する方法としては、例えば、バリアフィルムの透明バリア層上に第２の接着層を介して保護層を積層する方法が挙げられる。この場合、ドライラミネート法が好ましく用いられる。ドライラミネート法の場合、積層時に、透明バリア層にせん断がかかるのを抑制できる。 When the protective layer is a resin film and the barrier film has a transparent base material and a transparent barrier layer, the method for disposing the protective layer on the transparent barrier layer includes, for example, applying a second adhesive on the transparent barrier layer of the barrier film. A method of laminating protective layers via layers can be mentioned. In this case, a dry lamination method is preferably used. In the case of dry lamination, it is possible to suppress shearing of the transparent barrier layer during lamination.
　保護層が塗布膜である場合、保護層の形成方法としては、保護層の材料や種類に応じて適宜選択され、各種塗布法を用いることができる。 When the protective layer is a coating film, the method for forming the protective layer is appropriately selected depending on the material and type of the protective layer, and various coating methods can be used.
　また、保護層が樹脂フィルムであり、バリアフィルムが保護層および透明バリア層を有する場合、保護層の透明バリア層側の面には、透明バリア層との密着性向上のために、表面処理が施されていてもよい。 In addition, when the protective layer is a resin film and the barrier film has a protective layer and a transparent barrier layer, the surface of the protective layer on the transparent barrier layer side may be subjected to surface treatment to improve adhesion with the transparent barrier layer. may have been applied.
６．オーバーコート層
　本開示における集電シート用フィルムは、例えば図７（ｃ）、（ｄ）に示すように、透明バリア層５２と接着層５３との間にオーバーコート層５７を有していてもよい。集電シート用フィルムが、透明バリア層に加えてオーバーコート層を有することにより、バリア性を高めることができる。オーバーコート層は、通常、透明バリア層とともに、バリアフィルムを構成する部材である。 6. Overcoat layer The film for current collector sheet in the present disclosure may have an overcoat layer 57 between the transparent barrier layer 52 and the adhesive layer 53, as shown in FIGS. 7(c) and 7(d), for example. good. When the current collector sheet film has an overcoat layer in addition to the transparent barrier layer, barrier properties can be improved. The overcoat layer is usually a member that constitutes a barrier film together with the transparent barrier layer.
　例えば図７（ｃ）に示すように、集電シート用フィルム５０が保護層５６を有する場合であって、バリアフィルム５５が透明基材５１および透明バリア層５２を有する場合には、オーバーコート層５７は、透明バリア層５２と保護層５６との間に配置される。また、例えば図７（ｄ）に示すように、集電シート用フィルム５０が保護層５６を有する場合であって、バリアフィルム５５が保護層５６および透明バリア層５２を有する場合には、オーバーコート層５７は、透明基材５１と透明バリア層５２との間に配置される。 For example, as shown in FIG. 7C, when the current collector sheet film 50 has a protective layer 56 and the barrier film 55 has a transparent base material 51 and a transparent barrier layer 52, an overcoat layer 57 is arranged between the transparent barrier layer 52 and the protective layer 56. For example, as shown in FIG. 7D, when the current collector sheet film 50 has a protective layer 56 and the barrier film 55 has a protective layer 56 and a transparent barrier layer 52, an overcoat Layer 57 is disposed between transparent substrate 51 and transparent barrier layer 52.
　オーバーコート層の材料としては、一般にバリアコート剤やオーバーコート剤として用いられている材料を使用できる。オーバーコート層は、有機物のみを含んでいてもよく、無機物および有機物の混合物を含んでいてもよい。中でも、オーバーコート層は、無機物および有機物の混合物を含むことが好ましい。水蒸気バリア性を高めることができる。 As the material for the overcoat layer, materials commonly used as barrier coating agents and overcoating agents can be used. The overcoat layer may contain only an organic substance, or may contain a mixture of an inorganic substance and an organic substance. Among these, it is preferable that the overcoat layer contains a mixture of an inorganic substance and an organic substance. Water vapor barrier properties can be improved.
　特に、オーバーコート層は、金属アルコキシドと親水基含有樹脂とを含有する樹脂組成物から生成された加水分解重縮合物を含むことが好ましい。水蒸気バリア性を向上させることができる。 In particular, the overcoat layer preferably contains a hydrolyzed polycondensate produced from a resin composition containing a metal alkoxide and a hydrophilic group-containing resin. Water vapor barrier properties can be improved.
　金属アルコキシドとしては、下記一般式で表される１種以上のアルコキシドが挙げられる。
　　　Ｒ１ ｎＭ（ＯＲ２）ｍ
（ただし、上記式中、Ｒ１、Ｒ２は、炭素数１以上、８以下の有機基を表し、Ｍは、金属原子を表し、ｎは、０以上の整数を表し、ｍは、１以上の整数を表し、ｎ＋ｍは、Ｍの原子価を表す。） Examples of the metal alkoxide include one or more alkoxides represented by the following general formula.
R 1 n M(OR 2 ) m
(However, in the above formula, R 1 and R 2 represent an organic group having 1 or more and 8 or less carbon atoms, M represents a metal atom, n represents an integer of 0 or more, and m is 1 or more. represents an integer, and n+m represents the valence of M.)
　上記式で表わされるアルコキシドの金属原子Ｍとしては、ケイ素、ジルコニウム、チタン、アルミニウム等が挙げられる。中でも、ケイ素が好ましい。 Examples of the metal atom M of the alkoxide represented by the above formula include silicon, zirconium, titanium, and aluminum. Among them, silicon is preferred.
　また、上記式において、ｎ＝０であることが好ましい。 Furthermore, in the above formula, it is preferable that n=0.
　上記式において、金属原子Ｍがケイ素であり、ｎ＝０であるアルコキシシランの具体例としては、テトラメトキシシラン、テトラエトキシシラン、テトラプロポキシシラン、テトラブトキシシラン等を挙げることができる。ケイ素のアルコキシドは、テトラエトキシシラン（ＴＥＯＳ）が好ましい。 In the above formula, specific examples of alkoxysilanes in which the metal atom M is silicon and n=0 include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, and tetrabutoxysilane. The silicon alkoxide is preferably tetraethoxysilane (TEOS).
　上記式で表されるアルコキシドとしては、アルコキシドの部分加水分解物、アルコキシドの加水分解縮合物の少なくとも１種以上を使用できる。また、上記アルコキシドの部分加水分解物は、アルコキシ基のすべてが加水分解されるものに限定されず、１個以上が加水分解されているもの、および、その混合物であってもよい。さらに、加水分解の縮合物としては、部分加水分解アルコキシドの２量体以上のもの、具体的には、２～６量体のものを使用してもよい。 As the alkoxide represented by the above formula, at least one of partial hydrolysates of alkoxides and hydrolyzed condensates of alkoxides can be used. Further, the partial hydrolyzate of the alkoxide is not limited to one in which all of the alkoxy groups are hydrolyzed, but may be one in which one or more alkoxy groups are hydrolyzed, or a mixture thereof. Further, as the condensate for hydrolysis, a dimer or more of partially hydrolyzed alkoxide, specifically a dimer to hexamer, may be used.
　また、親水基含有樹脂としては、親水基を含む樹脂が挙げられる。具体的には、ポリビニルアルコール系樹脂、エチレン－ビニルアルコール共重合体、アクリル酸系樹脂、天然高分子系のメチルセルロース、カルボキシメチルセルロース、セルロースナノファイバー、多糖類等が挙げられる。中でも、ポリビニルアルコール系樹脂が好ましい。 Furthermore, examples of the hydrophilic group-containing resin include resins containing hydrophilic groups. Specific examples include polyvinyl alcohol resins, ethylene-vinyl alcohol copolymers, acrylic acid resins, natural polymers such as methyl cellulose, carboxymethyl cellulose, cellulose nanofibers, and polysaccharides. Among these, polyvinyl alcohol resin is preferred.
　上記樹脂組成物における親水基含有樹脂の含有量は、金属アルコキシドの含有量１００質量部に対して、例えば、５質量部以上２０質量部以下が好ましく、７質量部以上１８質量部以下がより好ましい。 The content of the hydrophilic group-containing resin in the resin composition is, for example, preferably 5 parts by mass or more and 20 parts by mass or less, more preferably 7 parts by mass or more and 18 parts by mass or less, based on 100 parts by mass of the metal alkoxide content. .
　上記加水分解重縮合物は、金属元素と酸素元素と親水基含有樹脂とを含有する混合化合物とすることができ、親水基含有樹脂中の炭素原子(Ｃ)と金属アルコキシド中の金属原子(Ｍ)との間に、酸素(Ｏ)を介したＣ－Ｏ－Ｍ結合を有することができる。中でも、上記加水分解重縮合物が、テトラエトキシシラン（ＴＥＯＳ）およびポリビニルアルコール系樹脂の重縮合物であることが好ましい。テトラエトキシシラン（ＴＥＯＳ）およびポリビニルアルコール系樹脂の重縮合物については、例えば特許第５５６８８９７号公報に開示されているものと同様である。 The above-mentioned hydrolyzed polycondensate can be a mixed compound containing a metal element, an oxygen element, and a hydrophilic group-containing resin, and the carbon atom (C) in the hydrophilic group-containing resin and the metal atom (M ) can have a C--O--M bond via oxygen (O). Among these, it is preferable that the hydrolyzed polycondensate is a polycondensate of tetraethoxysilane (TEOS) and a polyvinyl alcohol resin. The polycondensate of tetraethoxysilane (TEOS) and polyvinyl alcohol resin is the same as that disclosed in, for example, Japanese Patent No. 5,568,897.
　オーバーコート層は、必要に応じて、種々の添加剤を含んでいてもよい。 The overcoat layer may contain various additives as necessary.
　オーバーコート層の厚さは、特に限定されないが、例えば、１００ｎｍ以上４μｍ以下であり、２００ｎｍ以上１μｍ以下であってもよい。オーバーコート層の厚さが上記範囲内であれば、高いバリア性を維持しつつ、クラック等の発生を抑制できる。 The thickness of the overcoat layer is not particularly limited, but may be, for example, 100 nm or more and 4 μm or less, and may be 200 nm or more and 1 μm or less. If the thickness of the overcoat layer is within the above range, it is possible to suppress the occurrence of cracks and the like while maintaining high barrier properties.
　上記加水分解重縮合物を含むオーバーコート層の形成方法としては、例えば、ゾルゲル法による薄膜形成方法を挙げることができる。すなわち、金属アルコキシドと親水基含有樹脂とを含有し、さらに、ゾルゲル法によって重縮合して得られる原料液を用いる方法である。具体的には、まず、親水基含有樹脂を水系溶媒で溶解させた溶液に、金属アルコキシドまたはその加水分解物を混合して、コーティング液を調製する。上記水系溶媒としては、例えば、水、あるいは、水およびアルコールの混合溶媒を用いることができる。次いで、上記コーティング液を、透明バリア層上に塗布し、加熱乾燥し、加熱処理を行う。これにより、上記加水分解重縮合物を含むオーバーコート層が得られる。 Examples of the method for forming the overcoat layer containing the hydrolyzed polycondensate include a thin film forming method using a sol-gel method. That is, this method uses a raw material liquid containing a metal alkoxide and a hydrophilic group-containing resin, which is further obtained by polycondensation using a sol-gel method. Specifically, first, a metal alkoxide or a hydrolyzate thereof is mixed with a solution in which a hydrophilic group-containing resin is dissolved in an aqueous solvent to prepare a coating liquid. As the aqueous solvent, for example, water or a mixed solvent of water and alcohol can be used. Next, the coating liquid is applied onto the transparent barrier layer, dried by heating, and subjected to heat treatment. As a result, an overcoat layer containing the above hydrolyzed polycondensate is obtained.
７．その他
　本開示における集電シート用フィルムの厚さは、上述の集電シート用樹脂フィルムの厚さと同様である。 7. Others The thickness of the current collector sheet film in the present disclosure is the same as the thickness of the above-mentioned current collector sheet resin film.
ＩＩ．集電シート用フィルムの物性
１．水蒸気透過度
　本開示における集電シート用フィルムは、透明バリア層を有することにより、水蒸気バリア性を有する。集電シート用フィルムの水蒸気透過度は、例えば、１×１０－３ｇ／（ｍ２・ｄａｙ）以上、１ｇ／（ｍ２・ｄａｙ）以下が好ましく、１×１０－３ｇ／（ｍ２・ｄａｙ）以上、１×１０－１ｇ／（ｍ２・ｄａｙ）以下がより好ましく、１×１０－３ｇ／（ｍ２・ｄａｙ）以上、１×１０－２ｇ／（ｍ２・ｄａｙ）以下がさらに好ましい。 II. Physical properties of film for current collector sheet 1. Water Vapor Permeability The film for current collector sheet in the present disclosure has water vapor barrier properties by having a transparent barrier layer. The water vapor permeability of the current collector sheet film is, for example, preferably 1×10 −3 g/(m 2 ·day) or more and 1 g/(m 2 ·day) or less, and 1×10 −3 g/(m 2 · day) or less.・day) or more and 1×10 −1 g/(m 2・day) or less is more preferable, and 1×10 −3 g/(m 2・day) or more and 1×10 −2 g/(m 2・day) ) The following are more preferable.
　ここで、水蒸気透過度の測定は、ＩＳＯ　１５１０６－５：２０１５（差圧法）に準拠して、温度４０℃、相対湿度差９０％ＲＨの条件で、水蒸気透過度測定装置を用いて測定する。水蒸気透過度測定装置としては、英国Ｔｅｃｈｎｏｌｏｘ社製「ＤＥＬＴＡＰＥＲＭ」を用いる。測定は、集電シート用フィルムの表面のうち、集電シート用フィルムの厚さ方向において透明基材に対して透明バリア層側に位置する表面が高湿度側（水蒸気供給側）となるようにして、水蒸気透過度測定装置の上室と下室との間に集電シート用フィルムを装着し、透過面積５０．２４ｃｍ２（透過領域：直径８ｃｍの円形）として上記の条件で行う。１つの条件で少なくとも３つのサンプルを測定し、それらの測定値の平均をその条件での水蒸気透過度の値とする。 Here, the water vapor permeability is measured in accordance with ISO 15106-5:2015 (differential pressure method) under conditions of a temperature of 40° C. and a relative humidity difference of 90% RH using a water vapor permeability measuring device. As a water vapor permeability measuring device, "DELTAPERM" manufactured by Technolox, UK is used. The measurement was performed so that the surface of the current collector sheet film that is located on the transparent barrier layer side with respect to the transparent base material in the thickness direction of the current collector sheet film is the high humidity side (water vapor supply side). A current collector sheet film was installed between the upper and lower chambers of the water vapor permeability measuring device, and the measurement was conducted under the above conditions with a permeation area of 50.24 cm 2 (permeation area: circular 8 cm in diameter). At least three samples are measured under one condition, and the average of those measured values is taken as the water vapor permeability value under that condition.
２．波長４００ｎｍ以上１２００ｎｍ以下における光線透過率
　本開示における集電シート用フィルムの波長４００ｎｍ以上１２００ｎｍ以下における光線透過率は、上述の集電シート用樹脂フィルムの波長４００ｎｍ以上１２００ｎｍ以下における光線透過率と同様である。 2. Light transmittance at a wavelength of 400 nm or more and 1200 nm or less The light transmittance of the film for a current collector sheet in the present disclosure at a wavelength of 400 nm or more and 1200 nm or less is the same as the light transmittance of the above-mentioned resin film for a current collector sheet at a wavelength of 400 nm or more and 1200 nm or less. be.
３．ヘイズ
　本開示における集電シート用フィルムの透明性は、太陽電池素子が発電可能な程度に太陽光を透過させることができる程度であれば特に限定されない。集電シート用フィルムの透明性は、例えば、ヘイズによって評価できる。集電シート用フィルムのヘイズは、上述の集電シート用樹脂フィルムのヘイズと同様である。 3. Haze The transparency of the current collector sheet film in the present disclosure is not particularly limited as long as it can transmit sunlight to the extent that the solar cell element can generate electricity. The transparency of the current collector sheet film can be evaluated, for example, by haze. The haze of the current collector sheet film is the same as the haze of the above-mentioned current collector sheet resin film.
　なお、集電シート用フィルムのヘイズを測定するに際しては、測定用サンプルを作製し、測定に供する。測定用サンプルの作製方法は、上述の集電シート用樹脂フィルムのヘイズを測定する際の測定用サンプルの作製方法と同様である。 Note that when measuring the haze of the film for current collector sheet, a measurement sample is prepared and used for measurement. The method for preparing the sample for measurement is the same as the method for preparing the sample for measurement when measuring the haze of the resin film for current collector sheet described above.
ＩＩＩ．集電シート用フィルムの製造方法
　本開示における集電シート用フィルムの製造方法は、透明基材と透明バリア層と接着層と封止層とをこの順に有する集電シート用フィルムを得ることができれば特に限定されない。例えば、透明基材および透明バリア層を有するバリアフィルムと、フィルム状の封止層とを用い、ドライラミネート法により、バリアフィルムおよび封止層をドライラミネート用接着剤を介して積層する方法や、透明基材および透明バリア層を有するバリアフィルムを用い、押し出しラミネート法により、バリアフィルム上に封止層を押し出しラミネート用アンカーコート剤を介して積層する方法等が挙げられる。 III. Method for producing a film for a current collector sheet The method for producing a film for a current collector sheet in the present disclosure is such that a film for a current collector sheet having a transparent base material, a transparent barrier layer, an adhesive layer, and a sealing layer in this order can be obtained. Not particularly limited. For example, a method in which a barrier film having a transparent base material and a transparent barrier layer and a film-like sealing layer are used and the barrier film and the sealing layer are laminated via a dry laminating adhesive by a dry lamination method; Examples include a method in which a barrier film having a transparent base material and a transparent barrier layer is used, and a sealing layer is extruded onto the barrier film and laminated via an anchor coating agent for lamination by an extrusion lamination method.
　また、集電シート用フィルムが、透明基材と透明バリア層と保護層と接着層と封止層とをこの順に有する場合には、例えば、透明基材および透明バリア層を有するバリアフィルムと、フィルム状の保護層と、フィルム状の封止層とを用い、ドライラミネート法または押し出しラミネート法により、各フィルムを接着剤を介して積層する方法や、フィルム状の透明基材と、透明バリア層および保護層を有するバリアフィルムと、フィルム状の封止層とを用い、ドライラミネート法または押し出しラミネート法により、各フィルムを接着剤を介して積層する方法等が挙げられる。 Moreover, when the film for current collector sheet has a transparent base material, a transparent barrier layer, a protective layer, an adhesive layer, and a sealing layer in this order, for example, a barrier film having a transparent base material and a transparent barrier layer, A method in which a film-like protective layer and a film-like sealing layer are used, and each film is laminated via an adhesive using a dry lamination method or an extrusion lamination method, or a film-like transparent base material and a transparent barrier layer are used. Another method includes a method in which a barrier film having a protective layer and a film-like sealing layer are used, and each film is laminated via an adhesive by a dry lamination method or an extrusion lamination method.
　バリアフィルムの作製方法としては、例えば、フィルム状の透明基材または保護層を用い、透明基材または保護層上に透明バリア層を形成する方法が挙げられる。また、バリアフィルムの作製方法においては、透明バリア層上にオーバーコート層を形成してもよい。透明バリア層の形成方法およびオーバーコート層の形成方法は、上述の通りである。 Examples of the method for producing a barrier film include a method of using a film-like transparent base material or a protective layer and forming a transparent barrier layer on the transparent base material or the protective layer. Furthermore, in the method for producing a barrier film, an overcoat layer may be formed on the transparent barrier layer. The method for forming the transparent barrier layer and the method for forming the overcoat layer are as described above.
　フィルム状の封止層の形成方法は、上述の集電シート用樹脂フィルムにおける、フィルム状のポリエチレン樹脂層の形成方法と同様である。 The method for forming the film-like sealing layer is the same as the method for forming the film-like polyethylene resin layer in the resin film for current collector sheet described above.
Ｃ．集電シート
　本開示における集電シートは、２つの実施態様を有する。 C. Current Collector Sheet The current collector sheet in the present disclosure has two embodiments.
Ｃ－１．集電シートの第１実施態様
　本開示における集電シートの第１実施態様は、太陽電池に用いられる集電シートであって、上述の集電シート用樹脂フィルムと、集電シート用樹脂フィルムのポリエチレン樹脂層の面側に配置されたワイヤと、を有する。 C-1. First Embodiment of Current Collector Sheet The first embodiment of the current collector sheet in the present disclosure is a current collector sheet used for a solar cell, which comprises the above-mentioned resin film for current collector sheet and resin film for current collector sheet. and a wire disposed on the surface side of the polyethylene resin layer.
　図２（ａ）、（ｂ）は、本実施態様の集電シートを例示する概略平面図および断面図であり、図２（ｂ）は図２（ａ）のＡ－Ａ線断面図である。図２（ａ）、（ｂ）に示すように、集電シート２０は、集電シート用樹脂フィルム１０と、集電シート用樹脂フィルム１０のポリエチレン樹脂層３の面側に配置されたワイヤ１１とを有する。なお、図２（ａ）は、集電シート用樹脂フィルムのポリエチレン樹脂層側から集電シートを見た概略平面図を示している。 2(a) and 2(b) are a schematic plan view and a cross-sectional view illustrating the current collector sheet of this embodiment, and FIG. 2(b) is a cross-sectional view taken along the line AA in FIG. 2(a). . As shown in FIGS. 2A and 2B, the current collector sheet 20 includes a resin film 10 for a current collector sheet, and a wire 11 disposed on the surface side of the polyethylene resin layer 3 of the resin film 10 for a current collector sheet. and has. Note that FIG. 2(a) shows a schematic plan view of the current collecting sheet viewed from the polyethylene resin layer side of the resin film for current collecting sheet.
　本実施態様の集電シートにおいては、上述の集電シート用樹脂フィルムを有することにより、集電シート用樹脂フィルムによって、太陽電池素子に対してワイヤを良好に固定できる。また、集電シート用樹脂フィルムによって、熱によるワイヤの位置ずれを抑制できる。よって、集電シートを太陽電池に用いた場合には、発電効率を良くし、信頼性を向上させることができる。 In the current collecting sheet of this embodiment, by having the above-mentioned resin film for current collecting sheet, the wire can be well fixed to the solar cell element by the resin film for current collecting sheet. Moreover, the resin film for the current collector sheet can suppress the displacement of the wire due to heat. Therefore, when the current collecting sheet is used in a solar cell, power generation efficiency can be improved and reliability can be improved.
Ｉ．集電シートの構成
　本実施態様の集電シートは、集電シート用樹脂フィルムと、ワイヤと、を有する。 I. Configuration of Current Collector Sheet The current collector sheet of this embodiment includes a resin film for a current collector sheet and a wire.
１．集電シート用樹脂フィルム
　集電シート用樹脂フィルムは、ワイヤを支持する部材である。また、集電シート用樹脂フィルムは、太陽電池素子に対しワイヤを固定する部材である。 1. Resin film for current collector sheet The resin film for current collector sheet is a member that supports the wire. Moreover, the resin film for current collector sheet is a member that fixes the wire to the solar cell element.
　集電シート用樹脂フィルムについては、上述した「Ａ．集電シート用樹脂フィルム」で説明した内容と同様であるため、ここでの説明は省略する。 The resin film for the current collector sheet is the same as that explained in "A. Resin film for the current collector sheet" above, so the explanation here will be omitted.
　後述するように、集電シートが複数枚の集電シート用樹脂フィルムを有する場合は、少なくとも１枚の集電シート用樹脂フィルムが、上述の集電シート用樹脂フィルムであればよい。この場合、集電シートは、集電シート用樹脂フィルムとして、上述の集電シート用樹脂フィルム以外の他の集電シート用樹脂フィルムを有していてもよい。中でも、集電シートが有する複数枚の集電シート用樹脂フィルムの全てが、上述の集電シート用樹脂フィルムであることが好ましい。 As described later, when the current collecting sheet has a plurality of resin films for current collecting sheet, at least one resin film for current collecting sheet may be the above-mentioned resin film for current collecting sheet. In this case, the current collector sheet may have a resin film for current collector sheet other than the above-mentioned resin film for current collector sheet. Among these, it is preferable that all of the plurality of current collector sheet resin films included in the current collector sheet are the above-mentioned current collector sheet resin films.
２．ワイヤ
　ワイヤは、集電シート用樹脂フィルムのポリエチレン樹脂層の面側に配置される。ワイヤは、例えば、太陽電池モジュールにおいて、太陽電池素子同士を接続するために用いられる。また、ワイヤは、例えば、単セル型の太陽電池において、太陽電池素子で発生した電気を集電するために用いられる。ワイヤは、通常、太陽電池素子の電極と接続するように配置される。 2. Wire The wire is arranged on the surface side of the polyethylene resin layer of the resin film for current collector sheet. Wires are used, for example, in solar cell modules to connect solar cell elements to each other. Further, the wire is used, for example, in a single cell type solar cell to collect electricity generated in a solar cell element. The wire is usually arranged to connect with the electrode of the solar cell element.
　ワイヤの断面形状は、典型的には、真円形状、楕円形状等の円形状であるが、これに限定されない。 The cross-sectional shape of the wire is typically circular, such as a perfect circle or an ellipse, but is not limited thereto.
　ワイヤの太さ、すなわちワイヤの断面の大きさは、太陽電池素子への太陽光の入射を妨げない程度であれば、特に限定されず、例えば、１００μｍ以上３００μｍ以下である。ワイヤの断面の大きさは、例えば、断面形状が円形状である場合は直径をいい、楕円である場合は長径をいい、多角形である場合は最大の対角線の長さをいう。 The thickness of the wire, that is, the size of the cross section of the wire, is not particularly limited as long as it does not prevent sunlight from entering the solar cell element, and is, for example, 100 μm or more and 300 μm or less. The cross-sectional size of the wire is, for example, the diameter when the cross-section is circular, the major axis when the cross-section is elliptical, and the maximum diagonal length when the cross-section is polygonal.
　ワイヤの材料は、所望の導電性を示すことができれば特に限定されず、一般的な太陽電池素子の集電シートに用いられるワイヤの材料と同様である。ワイヤの材料としては、例えば、銅（Ｃｕ）、銀（Ａｇ）等の金属材料を用いることができる。また、ワイヤは、例えば、コア部と、コア部の外部側に配置された表皮部とを有していてもよい。この場合、コア部の材料としては、例えば、上記金属材料を用いることができる。また、表皮部の材料としては、はんだを用いることができる。 The material of the wire is not particularly limited as long as it can exhibit the desired conductivity, and is similar to the material of the wire used in current collector sheets of general solar cell elements. As the material of the wire, for example, metal materials such as copper (Cu) and silver (Ag) can be used. Further, the wire may have, for example, a core portion and a skin portion disposed on the outside of the core portion. In this case, as the material of the core part, for example, the above metal materials can be used. Furthermore, solder can be used as the material for the skin portion.
　はんだの融点は、例えば、７０℃以上１４０℃以下が好ましく、８０℃以上１３５℃以下がより好ましい。はんだの融点が高すぎると、太陽電池素子にワイヤを接続する際に、上記の基材層やポリエチレン樹脂層を劣化させる可能性がある。 The melting point of the solder is, for example, preferably 70°C or more and 140°C or less, more preferably 80°C or more and 135°C or less. If the melting point of the solder is too high, there is a possibility that the base material layer and the polyethylene resin layer described above will deteriorate when connecting wires to the solar cell element.
　このようなはんだとしては、例えば、Ｓｎ－Ｉｎ系、Ｂｉ－Ｓｎ系等が挙げられる。 Examples of such solder include Sn--In based solder, Bi--Sn based solder, and the like.
　例えば、Ｓｎ－Ｉｎ系のはんだやＩｎ－Ｂｉ系のはんだと比較して、Ｂｉ－Ｓｎ系のはんだは、融点が高い。そのため、Ｂｉ－Ｓｎ系のはんだを用いる場合には、集電シートを用いて集電シート付き太陽電池素子を製造する場合の加熱工程での加熱温度や、集電シート付き太陽電池素子を用いて太陽電池を製造する場合の加熱工程での加熱温度が、高くなる傾向にある。よって、上記の場合には、ワイヤの密着不良やワイヤの位置ずれが生じやすい。したがって、上記の場合には、特に本実施態様が有効である。 For example, compared to Sn-In-based solder and In-Bi-based solder, Bi-Sn-based solder has a higher melting point. Therefore, when using Bi-Sn solder, the heating temperature in the heating process when manufacturing a solar cell element with a current collector sheet and the solar cell element with a current collector sheet must be adjusted. The heating temperature in the heating process when manufacturing solar cells tends to be high. Therefore, in the above case, poor adhesion of the wires and misalignment of the wires are likely to occur. Therefore, this embodiment is particularly effective in the above case.
ＩＩ．集電シートの構造
　本実施態様の集電シートにおいては、１枚の集電シート用樹脂フィルムに対し、少なくとも１本以上のワイヤが配置されていればよい。集電シートの導電性を高める観点からは、１枚の集電シート用樹脂フィルムに対し、複数本のワイヤが配置されていることが好ましい。 II. Structure of Current Collecting Sheet In the current collecting sheet of this embodiment, at least one or more wires may be arranged for one resin film for current collecting sheet. From the viewpoint of increasing the conductivity of the current collector sheet, it is preferable that a plurality of wires are arranged for one resin film for current collector sheet.
　集電シートが複数本のワイヤを有する場合、平面視上のワイヤの配列は、特に限定されず、公知の集電シートにおけるワイヤの配列と同様である。例えば、図２（ａ）に示すように、ワイヤ１１がライン状に配置されていてもよく、図示しないが、ワイヤが格子状に配置されていてもよい。 When the current collector sheet has a plurality of wires, the arrangement of the wires in plan view is not particularly limited, and is similar to the arrangement of the wires in known current collector sheets. For example, as shown in FIG. 2(a), the wires 11 may be arranged in a line, or, although not shown, the wires may be arranged in a grid.
　また、集電シートにおいて、ワイヤは、集電シート用樹脂フィルムのポリエチレン樹脂層の面側に配置される。例えば図２（ｂ）に示すように、ワイヤ１１の一部が集電シート用樹脂フィルム１０のポリエチレン樹脂層３に埋め込まれ、ワイヤ１１の一部が露出するように、ワイヤ１１が配置されていることが好ましい。ワイヤを良好に固定できる。 Furthermore, in the current collector sheet, the wire is arranged on the surface side of the polyethylene resin layer of the resin film for the current collector sheet. For example, as shown in FIG. 2(b), the wire 11 is arranged so that a part of the wire 11 is embedded in the polyethylene resin layer 3 of the resin film 10 for current collector sheet, and a part of the wire 11 is exposed. Preferably. Wires can be fixed well.
　また、例えば、図２（ｂ）に示すように、ワイヤ１１が基材層１に接触しないようにポリエチレン樹脂層３に埋め込まれていてもよく、図８に示すように、ワイヤ１１が基材層１に接触するようにポリエチレン樹脂層３に埋め込まれていてもよい。ワイヤが基材層に接触するようにポリエチレン樹脂層に埋め込まれている場合には、集電シートの厚さを薄くできるので、集電シートを用いた太陽電池を薄型化することができる。 Further, for example, as shown in FIG. 2(b), the wire 11 may be embedded in the polyethylene resin layer 3 so as not to contact the base material layer 1, and as shown in FIG. It may be embedded in the polyethylene resin layer 3 so as to be in contact with the layer 1 . When the wire is embedded in the polyethylene resin layer so as to be in contact with the base material layer, the thickness of the current collector sheet can be reduced, so that the solar cell using the current collector sheet can be made thinner.
　ワイヤの埋め込みの程度、すなわち、ワイヤの露出の程度は、特に限定されず、ポリエチレン樹脂層の材料および厚さ、ワイヤの太さ、ならびに集電シートが配置される太陽電池素子の形態に応じて適宜選択できる。 The degree of embedding of the wires, that is, the degree of exposure of the wires, is not particularly limited and depends on the material and thickness of the polyethylene resin layer, the thickness of the wires, and the form of the solar cell element in which the current collector sheet is arranged. You can choose as appropriate.
　集電シートにおいては、例えば、複数枚の集電シート用樹脂フィルムに対し、同一のワイヤが配置されていてもよい。例えば、図９は、２枚の集電シート用樹脂フィルム１０Ａおよび集電シート用樹脂フィルム１０Ｂに対し、同一のワイヤ１１が配置されている例を示している。また、図９に示すように、隣接する集電シート用樹脂フィルム１０Ａ、１０Ｂ同士は、互いにポリエチレン樹脂層３側の面が逆の面方向となるように配置されていてもよい。すなわち、一方の集電シート用樹脂フィルム１０Ａのポリエチレン樹脂層３側の面と、他方の集電シート用樹脂フィルム１０Ｂの基材層１側の面とが、同一の面方向に配置されていてもよい。集電シートが上記構造を有することにより、例えば図３（ａ）に示すように、２つの太陽電池素子３１を直列に配置することが可能な集電シート２０とすることができる。なお、図示しないが、隣接する集電シート用樹脂フィルム同士は、互いにポリエチレン樹脂層側の面が同一の面方向となるように配置されていてもよい。 In the current collecting sheet, for example, the same wire may be arranged on a plurality of resin films for current collecting sheets. For example, FIG. 9 shows an example in which the same wire 11 is arranged for two resin films 10A and 10B for current collector sheets. Moreover, as shown in FIG. 9, adjacent resin films 10A and 10B for current collector sheets may be arranged so that the surfaces facing the polyethylene resin layer 3 are opposite to each other. That is, the surface of one resin film for current collector sheet 10A on the polyethylene resin layer 3 side and the surface of the other resin film for current collector sheet 10B on the base material layer 1 side are arranged in the same surface direction. Good too. By having the current collector sheet having the above structure, the current collector sheet 20 can be made into a current collector sheet 20 in which two solar cell elements 31 can be arranged in series, as shown in FIG. 3(a), for example. Although not shown, adjacent resin films for current collector sheets may be arranged so that their surfaces facing the polyethylene resin layer are in the same surface direction.
ＩＩＩ．集電シートの製造方法
　本実施態様の集電シートの製造方法としては、集電シート用樹脂フィルムのポリエチレン樹脂層の面側にワイヤを固定できる程度に埋め込むことができる方法であれば特に限定されず、公知の方法を用いることができる。一例としては、集電シート用樹脂フィルムのポリエチレン樹脂層の面側にワイヤを置き、ワイヤを加熱することで、ポリエチレン樹脂層中のポリエチレン樹脂の一部を溶融させて、ワイヤを埋め込む方法を挙げることができる。 III. Method for manufacturing current collector sheet The method for manufacturing the current collector sheet of this embodiment is particularly limited as long as it is a method that can embed wires to the surface side of the polyethylene resin layer of the resin film for current collector sheet to the extent that they can be fixed. First, a known method can be used. One example is a method in which a wire is placed on the side of the polyethylene resin layer of a resin film for a current collector sheet, and by heating the wire, a part of the polyethylene resin in the polyethylene resin layer is melted and the wire is embedded. be able to.
Ｃ－２．集電シートの第２実施態様
　本開示における集電シートの第２実施態様は、太陽電池に用いられる集電シートであって、上述の集電シート用フィルムと、集電シート用フィルムの封止層の面側に配置されたワイヤと、を有する。 C-2. Second embodiment of the current collector sheet The second embodiment of the current collector sheet in the present disclosure is a current collector sheet used for a solar cell, and includes the above-mentioned current collector sheet film and sealing of the current collector sheet film. and a wire disposed on the surface side of the layer.
　図５（ａ）、（ｂ）は、本実施態様の集電シートを例示する概略平面図および断面図であり、図５（ｂ）は図５（ａ）のＡ－Ａ線断面図である。図５（ａ）、（ｂ）に示すように、集電シート２０は、集電シート用フィルム５０と、集電シート用フィルム５０の封止層５４の面側に配置されたワイヤ１１とを有する。なお、図５（ａ）は、集電シート用フィルムの封止層側から集電シートを見た概略平面図を示している。 5(a) and 5(b) are a schematic plan view and a cross-sectional view illustrating the current collector sheet of this embodiment, and FIG. 5(b) is a cross-sectional view taken along the line AA in FIG. 5(a). . As shown in FIGS. 5(a) and 5(b), the current collecting sheet 20 includes a current collecting sheet film 50 and a wire 11 disposed on the surface side of the sealing layer 54 of the current collecting sheet film 50. have Note that FIG. 5(a) shows a schematic plan view of the current collecting sheet viewed from the sealing layer side of the film for current collecting sheet.
　本実施態様の集電シートにおいては、上述の集電シート用フィルムを有することにより、バリア性を付与できる。したがって、集電シートを太陽電池に用いた場合には、バリア性を向上させることができ、信頼性を高めることができる。 In the current collector sheet of this embodiment, barrier properties can be imparted by having the above-described film for current collector sheet. Therefore, when the current collector sheet is used in a solar cell, barrier properties can be improved and reliability can be improved.
Ｉ．集電シートの構成
　本実施態様の集電シートは、集電シート用フィルムと、ワイヤと、を有する。 I. Configuration of current collector sheet The current collector sheet of this embodiment includes a current collector sheet film and a wire.
１．集電シート用フィルム
　集電シート用フィルムは、ワイヤを支持する部材である。また、集電シート用フィルムは、太陽電池素子に対しワイヤを固定する部材である。 1. Film for current collector sheet The film for current collector sheet is a member that supports the wire. Further, the current collector sheet film is a member that fixes the wire to the solar cell element.
　集電シート用フィルムについては、上述した「Ｂ．集電シート用フィルム」で説明した内容と同様であるため、ここでの説明は省略する。 Regarding the current collector sheet film, the content is the same as that described in "B. Current collector sheet film" above, so the description here will be omitted.
　後述するように、集電シートが複数枚の集電シート用フィルムを有する場合は、少なくとも１枚の集電シート用フィルムが、上述の集電シート用フィルムであればよい。この場合、集電シートは、集電シート用フィルムとして、上述の集電シート用フィルム以外の他の集電シート用フィルムを有していてもよい。中でも、集電シートが有する複数枚の集電シート用フィルムの全てが、上述の集電シート用フィルムであることが好ましい。 As described later, when the current collecting sheet has a plurality of current collecting sheet films, at least one current collecting sheet film may be the above-mentioned current collecting sheet film. In this case, the current collecting sheet may have a current collecting sheet film other than the above-mentioned current collecting sheet film. Among these, it is preferable that all of the plurality of current collecting sheet films included in the current collecting sheet are the above-mentioned current collecting sheet films.
２．ワイヤ
　ワイヤは、集電シート用フィルムの封止層の面側に配置される。ワイヤは、上述の集電シートの第１実施態様におけるワイヤと同様である。 2. Wire The wire is arranged on the surface side of the sealing layer of the current collector sheet film. The wire is the same as the wire in the first embodiment of the current collector sheet described above.
　ワイヤがコア部と表皮部とを有する場合、表皮部に用いられるはんだとしては、例えば、Ｓｎ－Ｉｎ－Ａｇ－Ｂｉ系、Ｓｎ－Ｉｎ系、Ｂｉ－Ｓｎ系等が挙げられる。 When the wire has a core part and a skin part, examples of the solder used for the skin part include Sn-In-Ag-Bi-based, Sn-In-based, Bi-Sn-based, and the like.
ＩＩ．集電シートの構造
　集電シートの構造は、上述の集電シートの第１実施態様の構造と同様である。上述の集電シートの第１実施態様の構造において、「図２（ａ）」「図２（ｂ）」を「図５（ａ）」「図５（ｂ）」に読み替え、「集電シート用樹脂フィルム」を「集電シート用フィルム」に読み替え、「ポリエチレン樹脂層」を「封止層」に読み替え、「基材層」を「透明基材」に読み替える。また、上述の集電シートの第１実施態様の構造において、図９については、「集電シート用樹脂フィルム１０Ａ、１０Ｂ」を「集電シート用フィルム５０Ａ、５０Ｂ」に置き換え、「ポリエチレン樹脂層４」を「封止層５４」に置き換え、「基材層１」を「透明基材５１」に置き換える。 II. Structure of current collector sheet The structure of the current collector sheet is similar to the structure of the first embodiment of the current collector sheet described above. In the structure of the first embodiment of the current collector sheet described above, "FIG. 2(a)" and "FIG. 2(b)" are read as "FIG. 5(a)" and "FIG. 5(b)". ``resin film for current collector sheets'' shall be read as ``film for current collector sheets,'' ``polyethylene resin layer'' shall be read as ``sealing layer,'' and ``base material layer'' shall be read as ``transparent base material.'' In the structure of the first embodiment of the current collector sheet described above, in FIG. 9, " resin films 10A, 10B for current collector sheet" are replaced with "films 50A, 50B for current collector sheet", 4" is replaced with "sealing layer 54", and "base material layer 1" is replaced with "transparent base material 51".
　また、例えば、集電シート用フィルム５０が透明バリア層５２および接着層５３の間に保護層を有さない場合には、図５（ｂ）に示すように、ワイヤ１１が透明バリア層５２に接触しないように封止層５４に埋め込まれていることが好ましい。 Further, for example, when the current collector sheet film 50 does not have a protective layer between the transparent barrier layer 52 and the adhesive layer 53, the wire 11 is attached to the transparent barrier layer 52 as shown in FIG. 5(b). It is preferable that they be embedded in the sealing layer 54 so as not to contact each other.
　また、例えば、集電シート用フィルム５０が透明バリア層５２および接着層５３の間に保護層５６を有する場合には、図１０（ａ）に示すように、ワイヤ１１が保護層５６に接触しないように封止層５４に埋め込まれていてもよく、図１０（ｂ）に示すように、ワイヤ１１が保護層５６に接触するように封止層５４に埋め込まれていてもよい。ワイヤが保護層に接触するように封止層に埋め込まれている場合には、集電シートの厚さを薄くできるので、集電シートを用いた太陽電池を薄型化することができる。 Further, for example, when the current collector sheet film 50 has a protective layer 56 between the transparent barrier layer 52 and the adhesive layer 53, the wire 11 does not come into contact with the protective layer 56, as shown in FIG. 10(a). Alternatively, as shown in FIG. 10(b), the wire 11 may be embedded in the sealing layer 54 so as to be in contact with the protective layer 56. When the wire is embedded in the sealing layer so as to be in contact with the protective layer, the thickness of the current collector sheet can be reduced, so that the solar cell using the current collector sheet can be made thinner.
ＩＩＩ．集電シートの製造方法
　本実施態様の集電シートの製造方法としては、集電シート用フィルムの封止層の面側にワイヤを固定できる程度に埋め込むことができる方法であれば特に限定されず、公知の方法を用いることができる。一例としては、集電シート用フィルムの封止層の面側にワイヤを置き、ワイヤを加熱することで、封止層中の樹脂成分の一部を溶融させて、ワイヤを埋め込む方法を挙げることができる。 III. Method for manufacturing current collector sheet The method for manufacturing the current collector sheet of this embodiment is not particularly limited as long as it is a method that can embed the wire to the side of the sealing layer of the film for current collector sheet to an extent that it can be fixed. , a known method can be used. One example is a method in which a wire is placed on the side of the sealing layer of the current collector sheet film, and the wire is heated to melt part of the resin component in the sealing layer and embed the wire. I can do it.
Ｄ．集電シート付き太陽電池素子
　本開示における集電シート付き太陽電池素子は、２つの実施態様を有する。 D. Solar Cell Element with Current Collector Sheet The solar cell element with current collector sheet in the present disclosure has two embodiments.
Ｄ－１．集電シート付き太陽電池素子の第１実施態様
　本開示における集電シート付き太陽電池素子の第１実施態様は、上述の集電シートと、集電シートのポリエチレン樹脂層の面側に配置され、ワイヤと電気的に接続された太陽電池素子と、を有する。 D-1. First embodiment of a solar cell element with a current collector sheet The first embodiment of a solar cell element with a current collector sheet in the present disclosure includes the above-mentioned current collector sheet, and a current collector sheet arranged on the surface side of the polyethylene resin layer, A solar cell element electrically connected to the wire.
　図３（ａ）～（ｃ）は、本実施態様の集電シート付き太陽電池素子を例示する概略斜視図および断面図であり、図３（ｂ）は図３（ａ）のＡ－Ａ線断面図であり、図３（ｃ）は図３（ａ）のＢ－Ｂ線断面図である。図３（ａ）～（ｃ）に示すように、集電シート付き太陽電池素子３０は、集電シート２０と、集電シート２０のポリエチレン樹脂層３の面側に配置され、ワイヤ１１と電気的に接続された太陽電池素子３１とを有する。図３（ａ）～（ｃ）は、集電シート２０が２枚の集電シート用樹脂フィルム１０を有し、それぞれの集電シート用樹脂フィルム１０に太陽電池素子３１が配置されている例を示している。 3(a) to 3(c) are a schematic perspective view and a sectional view illustrating a solar cell element with a current collector sheet according to the present embodiment, and FIG. 3(b) is a line AA in FIG. 3(a). 3(c) is a sectional view taken along line BB in FIG. 3(a). As shown in FIGS. 3(a) to 3(c), the solar cell element 30 with a current collector sheet is arranged on the surface side of the current collector sheet 20 and the polyethylene resin layer 3 of the current collector sheet 20, and is connected to the wire 11 and It has a solar cell element 31 which is connected to the solar cell element 31. 3(a) to (c) are examples in which the current collecting sheet 20 has two resin films 10 for current collecting sheets, and a solar cell element 31 is arranged on each resin film 10 for current collecting sheets. It shows.
　本実施態様の集電シート付き太陽電池素子においては、上述の集電シートの第１実施態様を有することにより、集電シート用樹脂フィルムによって、太陽電池素子に対してワイヤを良好に固定できる。また、集電シート用樹脂フィルムによって、熱によるワイヤの位置ずれを抑制できる。よって、集電シート付き太陽電池素子を太陽電池に用いた場合には、発電効率を良くし、信頼性を向上させることができる。 In the solar cell element with a current collector sheet of this embodiment, by having the above-described first embodiment of the current collector sheet, the wire can be well fixed to the solar cell element by the resin film for the current collector sheet. Moreover, the resin film for the current collector sheet can suppress the displacement of the wire due to heat. Therefore, when a solar cell element with a current collector sheet is used in a solar cell, power generation efficiency can be improved and reliability can be improved.
Ｉ．集電シート付き太陽電池素子の構成
　本実施態様の集電シート付き太陽電池素子は、集電シートと、太陽電池素子と、を有する。 I. Configuration of solar cell element with current collector sheet The solar cell element with current collector sheet of this embodiment includes a current collector sheet and a solar cell element.
１．集電シート
　集電シートについては、上述した「Ｃ．集電シート　Ｃ－１．集電シートの第１実施態様」で説明した内容と同様であるため、ここでの説明は省略する。 1. Current Collecting Sheet The current collecting sheet is the same as that described in the above-mentioned "C. Current Collecting Sheet C-1. First Embodiment of Current Collecting Sheet", so a description thereof will be omitted here.
　集電シート付き太陽電池素子が複数枚の集電シートを有する場合、少なくとも１枚の集電シートが、上述の集電シートであればよい。この場合、集電シート付き太陽電池素子は、集電シートとして、上述の集電シート以外の他の集電シートを有していてもよい。中でも、全ての集電シートが、上述の集電シートであることが好ましい。 When the solar cell element with a current collecting sheet has a plurality of current collecting sheets, at least one current collecting sheet may be the above-mentioned current collecting sheet. In this case, the solar cell element with a current collecting sheet may have a current collecting sheet other than the above-mentioned current collecting sheet. Among these, it is preferable that all the current collecting sheets are the above-mentioned current collecting sheets.
２．太陽電池素子
　太陽電池素子は、一般的な太陽電池に用いられる素子と同様である。太陽電池素子としては、例えば、単結晶シリコン型太陽電池素子、多結晶シリコン型太陽電池素子、アモルファスシリコン型太陽電池素子、化合物半導体型太陽電池素子、色素増感型太陽電池素子、量子ドット型太陽電池素子、有機薄膜型太陽電池素子等が挙げられる。太陽電池素子の大きさ、形態等については、太陽電池の用途に応じて適宜選択できる。 2. Solar Cell Element The solar cell element is similar to the element used in general solar cells. Examples of the solar cell element include a single crystal silicon solar cell element, a polycrystalline silicon solar cell element, an amorphous silicon solar cell element, a compound semiconductor solar cell element, a dye-sensitized solar cell element, and a quantum dot solar cell element. Examples include battery elements, organic thin film type solar cell elements, and the like. The size, form, etc. of the solar cell element can be appropriately selected depending on the use of the solar cell.
ＩＩ．集電シート付き太陽電池素子の構造
　集電シート付き太陽電池素子は、通常、集電シートと太陽電池素子とが積層された積層構造を有する。 II. Structure of a solar cell element with a current collector sheet A solar cell element with a current collector sheet usually has a laminated structure in which a current collector sheet and a solar cell element are laminated.
　集電シート付き太陽電池素子は、太陽電池素子の集電シートの配置面を基準として見たとき、例えば図３（ｃ）に示すように、配置面に対する垂直方向ＤＬでの集電シート用樹脂フィルム１０の厚さ、すなわち、太陽電池素子３１の集電シート２０が配置された面から、基材層１の太陽電池素子３１とは反対側の面までの距離は、ワイヤ１１が配置された領域が他の領域に対して厚い（距離が大きい）ことが好ましい。このような積層構造とすることにより、基材層１が効果的にワイヤ１１を太陽電池素子３１側に押圧でき、ワイヤ１１の太陽電池素子３１に対する接触不良等の不具合を防止できる。 When the solar cell element with a current collector sheet is viewed from the arrangement surface of the current collector sheet of the solar cell element, for example, as shown in FIG . The thickness of the resin film 10, that is, the distance from the surface of the solar cell element 31 on which the current collector sheet 20 is arranged to the surface of the base material layer 1 on the opposite side to the solar cell element 31, is determined by the distance on which the wire 11 is arranged. It is preferable that the region is thicker (distance is larger) than other regions. With such a laminated structure, the base material layer 1 can effectively press the wire 11 toward the solar cell element 31 side, and problems such as poor contact of the wire 11 with the solar cell element 31 can be prevented.
　この場合、配置面に対する垂直方向ＤＬのワイヤ１１の最大距離ｙ、すなわち、ワイヤ１１の太陽電池素子３１の集電シート２０が配置された面からの最大距離ｙと、配置面に対する垂直方向ＤＬの集電シート用樹脂フィルム１０の最小距離ｘ、すなわち、太陽電池素子３１の集電シート２０が配置された面から、基材層１の太陽電池素子３１とは反対側の面までの距離のうちの最小距離ｘとの比率ｘ／ｙは、例えば、２／３以下が好ましく、１／２以下がより好ましい。 In this case, the maximum distance y of the wire 11 in the direction D L perpendicular to the arrangement surface, that is, the maximum distance y of the wire 11 from the surface on which the current collector sheet 20 of the solar cell element 31 is arranged, and the maximum distance y of the wire 11 in the direction D L perpendicular to the arrangement surface. The minimum distance x of the current collector sheet resin film 10 of L , that is, the distance from the surface of the solar cell element 31 on which the current collector sheet 20 is arranged to the surface of the base material layer 1 on the opposite side from the solar cell element 31 The ratio x/y with respect to the minimum distance x is, for example, preferably 2/3 or less, more preferably 1/2 or less.
　なお、上記比率ｘ／ｙの下限は、ポリエチレン樹脂層の厚さおよびワイヤの太さに応じて適宜調整される値ではあるが、例えば、１／２０以上である。上記比率がｘ／ｙが上記範囲内であることにより、集電シート用樹脂フィルムを用いて、太陽電池素子に対しワイヤを良好に固定できる。 Note that the lower limit of the ratio x/y is a value that is appropriately adjusted depending on the thickness of the polyethylene resin layer and the thickness of the wire, and is, for example, 1/20 or more. When the ratio x/y is within the above range, the wire can be well fixed to the solar cell element using the resin film for current collector sheet.
　ワイヤの太さ（直径等）およびポリエチレン樹脂層の厚さを調整することにより、上記比率ｘ／ｙを制御できる。また、後述するように、集電シートを太陽電池素子に熱圧着させる際の圧力を調整することによっても、上記比率ｘ／ｙを制御できる。 The above ratio x/y can be controlled by adjusting the thickness (diameter, etc.) of the wire and the thickness of the polyethylene resin layer. Further, as will be described later, the ratio x/y can also be controlled by adjusting the pressure when thermocompression bonding the current collector sheet to the solar cell element.
　また、例えば図３（ｃ）に示すように、集電シート付き太陽電池素子３０の断面視において、上記最大距離ｙとなる位置から上記最小距離ｘとなる位置に向かって、太陽電池素子３１の集電シート２０側の面から、基材層１の太陽電池素子３１とは反対側の面までの距離が徐々に小さくなっていることが好ましい。 Further, as shown in FIG. 3C, for example, in a cross-sectional view of the solar cell element 30 with a current collector sheet, the solar cell element 31 is It is preferable that the distance from the surface on the current collector sheet 20 side to the surface of the base material layer 1 on the opposite side to the solar cell element 31 gradually decreases.
　また、ワイヤが複数配置されている場合、例えば図３（ｃ）に示すように、集電シート付き太陽電池素子３０の断面視において、隣接するワイヤ１１の間に、太陽電池素子３１の集電シート２０が配置された面から、基材層１の太陽電池素子３１とは反対側の面までの距離のうち、最小の距離となる部分が配置されていることが好ましい。ワイヤ間に窪みができ、集電シートが凹凸形状を持つような構造になるので、基材層の太陽電池素子とは反対側の面の面積が大きくなる。これにより、集電シート付き太陽電池素子を有する太陽電池において、基材層と後述する封止材との接触面積が大きくなるので、封止材に対する密着性を向上させることができる。 In addition, when a plurality of wires are arranged, for example, as shown in FIG. It is preferable that the distance from the surface on which the sheet 20 is disposed to the surface of the base layer 1 opposite to the solar cell element 31 is disposed at the minimum distance. Since depressions are formed between the wires and the current collector sheet has an uneven structure, the area of the surface of the base material layer opposite to the solar cell element becomes large. Thereby, in a solar cell having a solar cell element with a current collector sheet, the contact area between the base layer and the encapsulant described later becomes large, so that adhesion to the encapsulant can be improved.
　また、集電シート付き太陽電池素子においては、上述の「Ｃ．集電シート　Ｃ－１．集電シートの第１実施態様」の項にも記載したように、例えば図３（ｃ）に示すように、ワイヤ１１が基材層１に接触するようにポリエチレン樹脂層３に埋め込まれていてもよい。これにより、集電シート付き太陽電池素子の厚さを薄くできるので、太陽電池を薄型化することができる。 In addition, in the solar cell element with a current collector sheet, as described in the section "C. Current collector sheet C-1. First embodiment of current collector sheet" above, for example, as shown in FIG. 3(c), As shown, the wire 11 may be embedded in the polyethylene resin layer 3 so as to be in contact with the base layer 1. Thereby, the thickness of the solar cell element with the current collecting sheet can be reduced, so that the solar cell can be made thinner.
　集電シート付き太陽電池素子は、少なくとも１つの太陽電池素子と、太陽電池素子の正極および負極の少なくとも一方の電極と接続された集電シートとを有していればよい。例えば、１つの太陽電池素子の正極および負極のそれぞれに集電シートが配置された、単セル型の太陽電池を構成する集電シート付き太陽電池素子であってもよい。また、例えば、集電シート付き太陽電池素子は、複数の太陽電池素子を集電シートを用いて並列または直列に接続した太陽電池モジュール型の太陽電池（太陽電池モジュール）を構成する集電シート付き太陽電池素子であってもよい。 The solar cell element with a current collecting sheet may include at least one solar cell element and a current collecting sheet connected to at least one of the positive and negative electrodes of the solar cell element. For example, it may be a solar cell element with a current collecting sheet that constitutes a single cell type solar cell, in which a current collecting sheet is placed on each of the positive electrode and the negative electrode of one solar cell element. For example, a solar cell element with a current collector sheet is a solar cell with a current collector sheet that constitutes a solar cell module type solar cell (solar cell module) in which multiple solar cell elements are connected in parallel or in series using a current collector sheet. It may also be a solar cell element.
ＩＩＩ．その他
　本実施態様の集電シート付き太陽電池素子の製造方法は、太陽電池素子に対し、集電シートのワイヤを電気的に接続させて固定した構造を得ることができる方法であれば特に限定されない。例えば、太陽電池素子に対し、集電シートを仮接着する仮接着工程と、仮接着された集電シートを太陽電池素子に熱圧着させることにより、太陽電池素子に対し集電シートのワイヤを電気的に接続させて固定する固定工程とを有する製造方法を挙げることができる。仮接着方法および熱圧着方法については、公知の方法を用いることができ、例えば、真空熱ラミネート法を挙げることができる。また、固定工程は、例えば後述する「Ｅ．太陽電池」の項で説明するように、太陽電池の各部材を積層させて一体化する一体化工程と同時に行ってもよい。 III. Others The method for manufacturing the solar cell element with a current collector sheet of this embodiment is not particularly limited as long as it is a method that can obtain a structure in which the wires of the current collector sheet are electrically connected and fixed to the solar cell element. . For example, by temporarily adhering a current collector sheet to a solar cell element, and by thermocompression bonding the temporarily adhered current collector sheet to the solar cell element, the wires of the current collector sheet can be electrically connected to the solar cell element. An example of a manufacturing method includes a fixing step of physically connecting and fixing. As for the temporary bonding method and the thermocompression bonding method, known methods can be used, such as a vacuum thermal lamination method. Further, the fixing step may be performed at the same time as the unifying step of laminating and integrating the respective members of the solar cell, for example, as described in the section "E. Solar Cell" below.
　集電シート付き太陽電池素子は、通常、太陽電池を構成する部材として用いられる。なお、集電シート付き太陽電池素子が、例えば、１つの太陽電池素子と、太陽電池素子の正極または負極のうち、一方の電極のみと接続された集電シートとを有する場合、集電シート付き太陽電池素子は、例えば、上記の単セル型の太陽電池の一部、または、上記の太陽電池モジュールを構成する集電シート付き太陽電池素子の一部として用いることができる。 A solar cell element with a current collector sheet is normally used as a member constituting a solar cell. In addition, when a solar cell element with a current collector sheet has, for example, one solar cell element and a current collector sheet connected to only one electrode of the positive electrode or the negative electrode of the solar cell element, the solar cell element with a current collector sheet The solar cell element can be used, for example, as a part of the above-mentioned single-cell type solar cell, or as a part of the solar cell element with a current collector sheet that constitutes the above-mentioned solar cell module.
Ｄ－２．集電シート付き太陽電池素子の第２実施態様
　本開示における集電シート付き太陽電池素子の第２実施態様は、上述の集電シートと、集電シートの封止層の面側に配置され、ワイヤと電気的に接続された太陽電池素子と、を有する。 D-2. Second embodiment of the solar cell element with a current collector sheet The second embodiment of the solar cell element with a current collector sheet in the present disclosure includes the above-mentioned current collector sheet, and the current collector sheet is arranged on the surface side of the sealing layer, A solar cell element electrically connected to the wire.
　図６（ａ）～（ｃ）は、本実施態様の集電シート付き太陽電池素子を例示する概略斜視図および断面図であり、図６（ｂ）は図６（ａ）のＡ－Ａ線断面図であり、図６（ｃ）は図６（ａ）のＢ－Ｂ線断面図である。図６（ａ）～（ｃ）に示すように、集電シート付き太陽電池素子３０は、集電シート２０と、集電シート２０の封止層５４の面側に配置され、ワイヤ１１と電気的に接続された太陽電池素子３１とを有する。図６（ａ）～（ｃ）は、集電シート２０が２枚の集電シート用フィルム５０を有し、それぞれの集電シート用フィルム５０に太陽電池素子３１が配置されている例を示している。 6(a) to 6(c) are a schematic perspective view and a cross-sectional view illustrating a solar cell element with a current collector sheet according to the present embodiment, and FIG. 6(b) is a line AA in FIG. 6(a). FIG. 6(c) is a sectional view taken along line BB in FIG. 6(a). As shown in FIGS. 6(a) to 6(c), the solar cell element 30 with a current collecting sheet is arranged on the surface side of the current collecting sheet 20 and the sealing layer 54 of the current collecting sheet 20, and is connected to the wire 11 and It has a solar cell element 31 which is connected to the solar cell element 31. 6(a) to (c) show an example in which the current collecting sheet 20 has two current collecting sheet films 50, and a solar cell element 31 is arranged on each current collecting sheet film 50. ing.
　本実施態様の集電シート付き太陽電池素子においては、上述の集電シートの第２実施態様を有することにより、バリア性を付与できる。したがって、集電シート付き太陽電池素子を太陽電池に用いた場合には、バリア性を向上させることができ、信頼性を高めることができる。 In the solar cell element with a current collector sheet of this embodiment, barrier properties can be imparted by having the second embodiment of the current collector sheet described above. Therefore, when a solar cell element with a current collector sheet is used in a solar cell, barrier properties can be improved and reliability can be improved.
Ｉ．集電シート付き太陽電池素子の構成
　本実施態様の集電シート付き太陽電池素子は、集電シートと、太陽電池素子と、を有する。 I. Configuration of solar cell element with current collector sheet The solar cell element with current collector sheet of this embodiment includes a current collector sheet and a solar cell element.
１．集電シート
　集電シートについては、上述した「Ｃ．集電シート　Ｃ－２．集電シートの第２実施態様」で説明した内容と同様であるため、ここでの説明は省略する。 1. Current Collecting Sheet The current collecting sheet is the same as that described in the above-mentioned "C. Current Collecting Sheet C-2. Second Embodiment of Current Collecting Sheet", so a description thereof will be omitted here.
　集電シート付き太陽電池素子が複数枚の集電シートを有する場合については、上述の集電付きシート付き太陽電池素子の第１実施態様と同様である。 The case where the solar cell element with a current collector sheet has a plurality of current collector sheets is the same as the first embodiment of the solar cell element with a current collector sheet described above.
　また、集電シート付き太陽電池素子を太陽電池に用いた場合については、上述の集電付きシート付き太陽電池素子の第１実施態様と同様である。 Furthermore, the case where the solar cell element with a current collector sheet is used as a solar cell is the same as the first embodiment of the solar cell element with a current collector sheet described above.
２．太陽電池素子
　太陽電池素子は、上述の集電付きシート付き太陽電池素子の第１実施態様における太陽電池素子と同様である。 2. Solar Cell Element The solar cell element is similar to the solar cell element in the first embodiment of the solar cell element with a current collector sheet described above.
ＩＩ．集電シート付き太陽電池素子の構造
　集電シート付き太陽電池素子の構造は、上述の集電シート付き太陽電池素子の第１実施態様の構造と同様である。上述の集電シート付き太陽電池素子の第１実施態様の構造において、「図３（ｃ）」を「図６（ｃ）」に読み替え、「集電シート用樹脂フィルム」を「集電シート用フィルム」に読み替え、「ポリエチレン樹脂層」を「封止層」に読み替える。 II. Structure of solar cell element with current collector sheet The structure of the solar cell element with current collector sheet is similar to the structure of the first embodiment of the solar cell element with current collector sheet described above. In the structure of the first embodiment of the solar cell element with a current collector sheet described above, "FIG. 3(c)" is read as "FIG. 6(c)", and "resin film for current collecting sheet" is replaced with "resin film for current collecting sheet". ``film'' and ``polyethylene resin layer'' as ``sealing layer.''
　また、集電シート付き太陽電池素子においては、集電シート用フィルムが透明バリア層および接着層の間に保護層を有する場合には、上述の「Ｃ．集電シート　Ｃ－２．集電シートの第２実施態様」の項にも記載したように、図示しないが、ワイヤが保護層に接触するように封止層に埋め込まれていてもよい。これにより、集電シート付き太陽電池素子の厚さを薄くできるので、太陽電池を薄型化することができる。 In addition, in the solar cell element with a current collector sheet, when the film for the current collector sheet has a protective layer between the transparent barrier layer and the adhesive layer, the above-mentioned "C. Current collector sheet C-2. Current collector sheet Although not shown, the wire may be embedded in the sealing layer so as to be in contact with the protective layer, as described in the section "Second Embodiment". Thereby, the thickness of the solar cell element with the current collecting sheet can be reduced, so that the solar cell can be made thinner.
ＩＩＩ．その他
　本実施態様の集電シート付き太陽電池素子の製造方法は、上述の集電シート付き太陽電池素子の第１実施態様の製造方法と同様である。また、集電シート付き太陽電池素子が太陽電池に用いられる場合についても、上述の集電シート付き太陽電池素子の第１実施態様と同様である。 III. Others The method for manufacturing the solar cell element with a current collector sheet of this embodiment is the same as the method of manufacturing the solar cell element with a current collector sheet of the first embodiment described above. Furthermore, the case where the solar cell element with a current collecting sheet is used in a solar cell is similar to the first embodiment of the solar cell element with a current collecting sheet described above.
Ｅ．太陽電池
　本開示における太陽電池は、２つの実施態様を有する。 E. Solar Cell The solar cell in this disclosure has two embodiments.
Ｅ－１．太陽電池の第１実施態様
　本開示における太陽電池の第１実施態様は、透明基板と、第１封止材と、上述の集電シート付き太陽電池素子と、第２封止材と、対向基板と、をこの順にする。 E-1. First Embodiment of Solar Cell The first embodiment of the solar cell according to the present disclosure includes a transparent substrate, a first encapsulant, the above-described solar cell element with a current collector sheet, a second encapsulant, and a counter substrate. and in this order.
　図１１は、本実施態様の太陽電池を例示する概略断面図である。図１１に示すように、太陽電池４０は、透明基板４１と、第１封止材４２と、集電シート付き太陽電池素子３０と、第２封止材４３と、対向基板４４とを有する。 FIG. 11 is a schematic cross-sectional view illustrating the solar cell of this embodiment. As shown in FIG. 11, the solar cell 40 includes a transparent substrate 41, a first encapsulant 42, a solar cell element 30 with a current collector sheet, a second encapsulant 43, and a counter substrate 44.
　本実施態様の太陽電池は、複数の集電シート付き太陽電池素子を有する太陽電池モジュールであってもよい。 The solar cell of this embodiment may be a solar cell module having a plurality of solar cell elements with current collecting sheets.
　本実施態様の太陽電池においては、上述の集電シート付き太陽電池素子の第１実施態様を有することにより、集電シート用樹脂フィルムによって、太陽電池素子に対してワイヤを良好に固定できる。また、集電シート用樹脂フィルムによって、熱によるワイヤの位置ずれを抑制できる。よって、発電効率を良くし、信頼性を向上させることができる。 In the solar cell of this embodiment, by having the above-described first embodiment of the solar cell element with a current collecting sheet, the wire can be well fixed to the solar cell element by the resin film for the current collecting sheet. Moreover, the resin film for the current collector sheet can suppress the displacement of the wire due to heat. Therefore, power generation efficiency can be improved and reliability can be improved.
Ｉ．太陽電池の構成
　本実施態様の太陽電池は、透明基板と、第１封止材と、集電シート付き太陽電池素子と、第２封止材と、対向基板と、をこの順に有する。 I. Structure of Solar Cell The solar cell of this embodiment includes, in this order, a transparent substrate, a first encapsulant, a solar cell element with a current collector sheet, a second encapsulant, and a counter substrate.
１．集電シート付き太陽電池素子
　集電シート付き太陽電池素子については、上述した「Ｄ．集電シート付き太陽電池素子　Ｄ－１．集電シート付き太陽電池素子の第１実施態様」の項で説明した内容と同様であるため、ここでの説明は省略する。 1. Solar cell element with current collector sheet The solar cell element with current collector sheet is explained in the above section "D. Solar cell element with current collector sheet D-1. First embodiment of solar cell element with current collector sheet" Since the contents are the same as those described above, the explanation here will be omitted.
２．透明基板および対向基板
　透明基板は、対向基板とともに、太陽電池素子を保護する部材である。また、透明基板は、通常、太陽電池の受光面側に配置され、受光面側の前面保護板として機能する。透明基板の透明性は、太陽電池素子の発電を阻害しない程度であれば特に限定されない。透明基板としては、一般的な太陽電池に用いられる透明基板と同様であるため、ここでの説明は省略する。 2. Transparent Substrate and Counter Substrate The transparent substrate is a member that protects the solar cell element together with the counter substrate. Further, the transparent substrate is usually arranged on the light-receiving surface side of the solar cell, and functions as a front protection plate on the light-receiving surface side. The transparency of the transparent substrate is not particularly limited as long as it does not inhibit the power generation of the solar cell element. Since the transparent substrate is the same as a transparent substrate used in a general solar cell, a description thereof will be omitted here.
　対向基板は、上記透明基板とともに、太陽電池素子を保護する部材である。対向基板は、透明性を有していてもよく、透明性を有していなくてもよい。対向基板が透明性を有する場合は、太陽電池の両面を太陽光の受光面として用いることができる。対向基板としては、上述した透明基板を用いることができる。また、対向基板としては、太陽電池用の裏面保護シートを用いることもできる。 The counter substrate is a member that protects the solar cell element together with the transparent substrate. The counter substrate may or may not have transparency. When the counter substrate has transparency, both surfaces of the solar cell can be used as sunlight receiving surfaces. As the counter substrate, the above-mentioned transparent substrate can be used. Further, as the counter substrate, a back protection sheet for solar cells can also be used.
３．第１封止材および第２封止材
　第１封止材および第２封止部材は、太陽電池素子を封止する部材である。第１封止材は、通常、太陽電池の受光面側に配置される。 3. First Encapsulant and Second Encapsulant The first encapsulant and the second encapsulant are members that seal the solar cell element. The first sealing material is usually placed on the light-receiving surface side of the solar cell.
　第１封止材および第２封止部材は、熱可塑性樹脂を含有する。第１封止材および第２封止部材に用いられる熱可塑性樹脂としては、一般的な太陽電池の封止材に用いられる熱可塑性樹脂と同様であり、例えば、ポリエチレン樹脂、エチレン－酢酸ビニル共重合体（ＥＶＡ）等の各種のオレフィン樹脂を主成分とする封止材を用いることができる。なお、これらの樹脂を主成分とするとは、全樹脂成分の中でもこれらの樹脂の割合が最も多いことをいう。 The first sealing material and the second sealing member contain thermoplastic resin. The thermoplastic resin used for the first encapsulant and the second encapsulant is the same as the thermoplastic resin used for the encapsulant of general solar cells, such as polyethylene resin, ethylene-vinyl acetate, etc. Encapsulants mainly composed of various olefin resins such as polymers (EVA) can be used. In addition, when these resins are the main components, it means that the ratio of these resins is the largest among all resin components.
　第１封止材は、通常、紫外線吸収剤を含有する。紫外線による、ポリエチレンテレフタレート樹脂を含有する基材層の劣化、例えば、黄変、クラック、破断等を抑制できる。 The first sealing material usually contains an ultraviolet absorber. Deterioration of the base material layer containing polyethylene terephthalate resin caused by ultraviolet rays, such as yellowing, cracking, and breakage, can be suppressed.
　上記対向基板が透明性を有する場合、第２封止材は、上記第１封止材と同様に、通常、紫外線吸収剤を含有する。 When the counter substrate has transparency, the second encapsulant usually contains an ultraviolet absorber, similar to the first encapsulant.
　紫外線吸収剤としては、一般的な太陽電池の封止材に用いられる紫外線吸収剤と同様である。 The ultraviolet absorber is similar to the ultraviolet absorber used in general solar cell encapsulants.
　第１封止材および第２封止材の厚さは、太陽電池の種類、大きさに応じて適宜選択される。 The thicknesses of the first encapsulant and the second encapsulant are appropriately selected depending on the type and size of the solar cell.
ＩＩ．太陽電池の製造方法
　本実施態様の太陽電池の製造方法は、一般的な太陽電池の製造方法と同様である。一例としては、透明基板、第１封止材、集電シート付き太陽電池素子、第２封止材および対向基板をこの順に積層した積層体を形成する積層体形成工程と、上記積層体に加熱および加圧処理することにより一体化して太陽電池とする一体化工程とを有する製造方法を挙げることができる。 II. Method for manufacturing a solar cell The method for manufacturing a solar cell in this embodiment is similar to the method for manufacturing a general solar cell. As an example, a laminate forming step of forming a laminate in which a transparent substrate, a first encapsulant, a solar cell element with a current collector sheet, a second encapsulant, and a counter substrate are laminated in this order, and heating the laminate. and a step of integrating them into a solar cell by pressure treatment.
　加熱および加圧処理は、特に限定されず、一般的な太陽電池の製造時において行われる処理と同様である。例えば、真空熱ラミネート法が好ましい。真空熱ラミネート法の条件は、特に限定されず、太陽電池の大きさ、各部材の種類等に応じて適宜選択できる。ラミネート温度は、例えば、１３０℃以上１７０℃以下が好ましい。また、ラミネート時間は、例えば、５分以上３０分以下が好ましく、８分以上１５分以下がより好ましい。 The heating and pressure treatments are not particularly limited, and are similar to those performed during the manufacture of general solar cells. For example, a vacuum thermal lamination method is preferred. The conditions for the vacuum thermal lamination method are not particularly limited, and can be appropriately selected depending on the size of the solar cell, the type of each member, etc. The lamination temperature is preferably, for example, 130°C or higher and 170°C or lower. Further, the lamination time is preferably, for example, 5 minutes or more and 30 minutes or less, and more preferably 8 minutes or more and 15 minutes or less.
ＩＩＩ．用途
　本実施態様の太陽電池の用途としては、例えば、電子機器用の太陽電池、屋外設置用の大型太陽電池等の種々の用途を挙げることができる。 III. Applications Examples of the applications of the solar cell of this embodiment include various applications such as solar cells for electronic devices and large solar cells for outdoor installation.
Ｅ－２．太陽電池の第２実施態様
　本開示における太陽電池の第２実施態様は、透明基板と、第１封止材と、上述の集電シート付き太陽電池素子と、第２封止材と、裏面保護シートと、をこの順にする。 E-2. Second Embodiment of Solar Cell A second embodiment of the solar cell according to the present disclosure includes a transparent substrate, a first encapsulant, the above-described solar cell element with a current collector sheet, a second encapsulant, and a back surface protection. Place the sheets and in this order.
　本実施態様の太陽電池を例示する概略断面図は、上述の太陽電池の第１実施態様における図１１において、「対向基板４４」を「裏面保護シート」に置き換えたものである。 The schematic cross-sectional view illustrating the solar cell of this embodiment is the one in FIG. 11 of the first embodiment of the solar cell described above, in which the "counter substrate 44" is replaced with a "back protection sheet".
　本実施態様の太陽電池は、複数の集電シート付き太陽電池素子を有する太陽電池モジュールであってもよい。 The solar cell of this embodiment may be a solar cell module having a plurality of solar cell elements with current collecting sheets.
　本実施態様の太陽電池においては、上述の集電シート付き太陽電池素子の第２実施態様を有することにより、バリア性を向上させることができ、信頼性高めることができる。 In the solar cell of this embodiment, by having the above-described second embodiment of the solar cell element with a current collector sheet, barrier properties can be improved and reliability can be improved.
Ｉ．太陽電池の構成
　本実施態様の太陽電池は、透明基板と、第１封止材と、集電シート付き太陽電池素子と、第２封止材と、裏面保護シートと、をこの順に有する。 I. Structure of Solar Cell The solar cell of this embodiment includes, in this order, a transparent substrate, a first encapsulant, a solar cell element with a current collector sheet, a second encapsulant, and a back protection sheet.
１．集電シート付き太陽電池素子
　集電シート付き太陽電池素子については、上述した「Ｄ．集電シート付き太陽電池素子　Ｄ－２．集電シート付き太陽電池素子の第２実施態様」の項で説明した内容と同様であるため、ここでの説明は省略する。 1. Solar cell element with current collector sheet The solar cell element with current collector sheet is explained in the above section "D. Solar cell element with current collector sheet D-2. Second embodiment of solar cell element with current collector sheet" Since the contents are the same as those described above, the explanation here will be omitted.
２．裏面保護シート
　裏面保護シートは、上記透明基板とともに、太陽電池素子を保護する部材である。裏面保護シートは、透明性を有していてもよく、透明性を有していなくてもよい。裏面保護シートが透明性を有する場合は、太陽電池の両面を太陽光の受光面として用いることができる。裏面保護シートとしては、一般的な太陽電池に用いられる裏面保護シートと同様である。 2. Back Protection Sheet The back protection sheet is a member that protects the solar cell element together with the transparent substrate. The back protection sheet may or may not have transparency. When the back protection sheet has transparency, both sides of the solar cell can be used as sunlight receiving surfaces. The back protection sheet is similar to the back protection sheet used for general solar cells.
　中でも、裏面保護シートは、後述の第２封止材側から順に、易接着層と、第２のバリアフィルムと、基材層とを有することが好ましい。 Among these, it is preferable that the back protection sheet has an easily adhesive layer, a second barrier film, and a base material layer in this order from the second encapsulant side, which will be described later.
　なお、本明細書において、便宜上、裏面保護シートが有するバリアフィルムを、第２のバリアフィルムと称する。 Note that in this specification, for convenience, the barrier film included in the back protection sheet is referred to as a second barrier film.
（１）第２のバリアフィルム
　第２のバリアフィルムは、基材とバリア層とを有することができる。第２のバリアフィルムは、通常、基材が易接着層側、バリア層が基材層側になるように配置される。 (1) Second barrier film The second barrier film can have a base material and a barrier layer. The second barrier film is usually arranged such that the base material is on the easily adhesive layer side and the barrier layer is on the base material layer side.
　バリア層は、透明性を有していてもよく、透明性を有していなくてもよい。 The barrier layer may or may not have transparency.
　バリア層については、上記集電シート用フィルムに用いられる透明バリア層と同様であるので、ここでの説明は省略する。 The barrier layer is the same as the transparent barrier layer used in the current collector sheet film, so the explanation here will be omitted.
　基材は、透明性を有していてもよく、透明性を有していなくてもよい。 The base material may or may not have transparency.
　基材については、上記集電シート用フィルムに用いられる透明基材と同様であるので、ここでの説明は省略する。 The base material is the same as the transparent base material used in the above-mentioned current collector sheet film, so the explanation here will be omitted.
　第２のバリアフィルムは、バリア層の基材とは反対の面側に第２のオーバーコート層を有することが好ましい。バリア性を向上させることができる。 The second barrier film preferably has a second overcoat layer on the side of the barrier layer opposite to the base material. Barrier properties can be improved.
　第２のオーバーコート層については、上記集電シート用フィルムに用いられるオーバーコート層と同様であるので、ここでの説明は省略する。 The second overcoat layer is the same as the overcoat layer used in the above-mentioned current collector sheet film, so a description thereof will be omitted here.
（２）基材層
　基材層は、一般的な太陽電池に用いられる裏面保護シートを構成する基材層と同様である。基材層としては、例えば、耐候性を有する樹脂フィルムを用いることができる。 (2) Base material layer The base material layer is the same as the base material layer that constitutes a back protection sheet used in general solar cells. As the base material layer, for example, a resin film having weather resistance can be used.
（３）易接着層
　易接着層は、裏面保護シートと第２封止材との密着性を高めるための部材である。易接着層としては、一般的な太陽電池に用いられる裏面保護シートを構成する易接着層と同様である。易接着層としては、例えば、ポリエチレンフィルムが挙げられる。 (3) Easy-adhesion layer The easy-adhesion layer is a member for increasing the adhesion between the back protection sheet and the second sealing material. The easily adhesive layer is the same as the easily adhesive layer that constitutes a back protection sheet used in general solar cells. Examples of the easily adhesive layer include polyethylene film.
（４）その他
　裏面保護シートにおいて、基材層および第２のガスバリアフィルムの間には、第３の接着層が配置されていてもよい。また、裏面保護シートにおいて、第２のガスバリアフィルムおよび易接着層の間には、第４の接着層が配置されていてもよい。第３の接着層および第４の接着層については、上記集電シート用フィルムに用いられる接着層と同様である。 (4) Others In the back protection sheet, a third adhesive layer may be disposed between the base layer and the second gas barrier film. Further, in the back protection sheet, a fourth adhesive layer may be disposed between the second gas barrier film and the easily adhesive layer. The third adhesive layer and the fourth adhesive layer are the same as the adhesive layer used in the above film for current collector sheet.
３．透明基板
　透明基板は、上述の太陽電池の第１実施態様における透明基板と同様である。 3. Transparent Substrate The transparent substrate is the same as the transparent substrate in the first embodiment of the solar cell described above.
４．第１封止材および第２封止材
　第１封止材および第２封止材は、上述の太陽電池の第１実施態様における第１封止材および第２封止材と同様である。 4. First encapsulant and second encapsulant The first encapsulant and second encapsulant are the same as the first encapsulant and second encapsulant in the first embodiment of the solar cell described above.
ＩＩ．太陽電池の製造方法
　本実施態様の太陽電池の製造方法は、上述の太陽電池の第１実施態様の製造方法と同様である。上述の太陽電池の第１実施態様の製造方法において、「対向基板」を「裏面保護シート」に読み替える。 II. Method for manufacturing a solar cell The method for manufacturing a solar cell in this embodiment is similar to the method for manufacturing a solar cell in the first embodiment described above. In the manufacturing method of the first embodiment of the solar cell described above, "counter substrate" is read as "back protection sheet".
ＩＩＩ．用途
　本実施態様の太陽電池の用途は、上述の太陽電池の第１実施態様の用途と同様である。 III. Applications The applications of the solar cell of this embodiment are the same as those of the first embodiment of the solar cell described above.
　なお、本開示は、上記実施形態に限定されない。上記実施形態は、例示であり、本開示の特許請求の範囲に記載された技術的思想と実質的に同一な構成を有し、同様な作用効果を奏するものは、いかなるものであっても本開示の技術的範囲に包含される。 Note that the present disclosure is not limited to the above embodiments. The above-mentioned embodiments are illustrative, and any embodiment that has substantially the same configuration as the technical idea stated in the claims of the present disclosure and provides similar effects is the present invention. within the technical scope of the disclosure.
［実施例１］
　基材層として、厚さ１２μｍのポリエチレンテレフタレート（ＰＥＴ）フィルム（デュポン社製「ＬＢＤ」）を用いた。また、接着剤（アンカーコート剤）として、ポリカーボネート系の主剤（ロックペイント社製「ＫＴ－００３５」）と、イソシアネート系の硬化剤（ロックペイント社製「Ｈ－０３９Ｚ２」）とからなる２液型接着剤を用いた。また、ポリエチレン樹脂として、密度０．９２ｇ／ｃｍ３、融点１０６℃、ＭＦＲ（１９０℃）７ｇ／１０分の高圧法低密度ポリエチレン（ＬＤＰＥ）を用いた。 [Example 1]
A polyethylene terephthalate (PET) film ("LBD" manufactured by DuPont) with a thickness of 12 μm was used as the base material layer. In addition, as an adhesive (anchor coating agent), a two-component type consisting of a polycarbonate-based main agent ("KT-0035" manufactured by Rock Paint Co., Ltd.) and an isocyanate-based curing agent ("H-039Z2" manufactured by Rock Paint Co., Ltd.) is used. Glue was used. Further, as the polyethylene resin, high-pressure low density polyethylene (LDPE) having a density of 0.92 g/cm 3 , a melting point of 106° C., and an MFR (190° C.) of 7 g/10 minutes was used.
　上記基材層の片面に、アンカー剤として上記接着剤を０．１ｇ／ｍ２塗布し、上記ポリエチレン樹脂を厚さ６０μｍで押し出して、ポリエチレン樹脂層を形成した。さらに、上記ポリエチレン樹脂層の基材層とは反対側の面にコロナ処理を施した。これにより、基材層と、接着層と、ポリエチレン樹脂層とをこの順に有する集電シート用樹脂フィルムを得た。 On one side of the base layer, 0.1 g/m 2 of the adhesive was applied as an anchor agent, and the polyethylene resin was extruded to a thickness of 60 μm to form a polyethylene resin layer. Furthermore, the surface of the polyethylene resin layer opposite to the base material layer was subjected to corona treatment. Thereby, a resin film for a current collector sheet having a base material layer, an adhesive layer, and a polyethylene resin layer in this order was obtained.
［実施例２］
　基材層に、２００℃、１０秒のアニール処理を施したこと以外は、実施例１と同様にして、集電シート用樹脂フィルムを作製した。 [Example 2]
A resin film for a current collector sheet was produced in the same manner as in Example 1, except that the base layer was annealed at 200° C. for 10 seconds.
［比較例１］
　基材層として、厚さ１２μｍのＰＥＴフィルムを用いた。また、接着剤（アンカーコート剤）として、ウレタン系接着剤を用いた。また、ポリエチレン樹脂として、融点１０９℃、ＭＦＲ（１９０℃）５．７ｇ／１０分の直鎖状低密度ポリエチレン（ＬＬＤＰＥ）を用いた。 [Comparative example 1]
A PET film with a thickness of 12 μm was used as the base layer. In addition, a urethane adhesive was used as the adhesive (anchor coating agent). Further, as the polyethylene resin, linear low density polyethylene (LLDPE) with a melting point of 109° C. and an MFR (190° C.) of 5.7 g/10 minutes was used.
　実施例１と同様にして、集電シート用樹脂フィルムを作製した。 A resin film for a current collector sheet was produced in the same manner as in Example 1.
［比較例２］
　基材層として、厚さ１２μｍのポリエチレンテレフタレート（ＰＥＴ）フィルム（東洋紡社製「Ｅ５１０４」）を用いた。また、接着剤（アンカーコート剤）として、ポリカーボネート系の主剤（ロックペイント社製「ＫＴ－００３５」）と、イソシアネート系の硬化剤（ロックペイント社製「Ｈ－０３９Ｚ２」）とからなる２液型接着剤を用いた。また、ポリエチレン樹脂層として、密度０．９１５ｇ／ｃｍ３、融点１０５℃、ＭＦＲ（１９０℃）２ｇ／１０分のメタロセン系直鎖状低密度ポリエチレン（Ｍ－ＬＬＤＰＥ）を含むポリエチレンフィルムを用いた。 [Comparative example 2]
A 12 μm thick polyethylene terephthalate (PET) film (“E5104” manufactured by Toyobo Co., Ltd.) was used as the base material layer. In addition, as an adhesive (anchor coating agent), a two-component type consisting of a polycarbonate-based main agent ("KT-0035" manufactured by Rock Paint Co., Ltd.) and an isocyanate-based curing agent ("H-039Z2" manufactured by Rock Paint Co., Ltd.) is used. Glue was used. Further, as the polyethylene resin layer, a polyethylene film containing metallocene linear low density polyethylene (M-LLDPE) having a density of 0.915 g/cm 3 , a melting point of 105° C., and an MFR (190° C.) of 2 g/10 minutes was used.
　ドライラミネート法により、基材層とポリエチレン樹脂層とを接着剤を介して貼り合わせることによって、集電シート用樹脂フィルムを得た。 A resin film for a current collector sheet was obtained by bonding the base material layer and the polyethylene resin layer together via an adhesive using a dry lamination method.
［比較例３］
　ポリエチレン樹脂層として、密度０．９１５ｇ／ｃｍ３、融点１１０℃、ＭＦＲ（１９０℃）２ｇ／１０分のメタロセン系直鎖状低密度ポリエチレン（Ｍ－ＬＬＤＰＥ）を含むポリエチレンフィルムを用いたこと以外は、比較例２と同様にして、集電シート用樹脂フィルムを作製した。 [Comparative example 3]
Except that a polyethylene film containing metallocene-based linear low-density polyethylene (M-LLDPE) with a density of 0.915 g/cm 3 , a melting point of 110°C, and an MFR (190°C) of 2 g/10 min was used as the polyethylene resin layer. A resin film for a current collector sheet was produced in the same manner as in Comparative Example 2.
［比較例４］
　ポリエチレン樹脂層の厚さを７０μｍとしたこと以外は、実施例１と同様にして、集電シート用樹脂フィルムを作製した。 [Comparative example 4]
A resin film for a current collector sheet was produced in the same manner as in Example 1 except that the thickness of the polyethylene resin layer was 70 μm.
［評価１］
（１）熱収縮率
　集電シート用樹脂フィルムのＭＤ方向およびＴＤ方向の熱収縮率は、ＡＳＴＭ　Ｄ１２０４に準拠して測定した。測定条件は、１５０℃、１０分間とした。 [Evaluation 1]
(1) Heat shrinkage rate The heat shrinkage rate of the resin film for current collector sheet in the MD direction and the TD direction was measured in accordance with ASTM D1204. The measurement conditions were 150°C and 10 minutes.
（２）波長４００ｎｍ以上１２００ｎｍ以下における光線透過率
　集電シート用樹脂フィルムの波長４００ｎｍ以上１２００ｎｍ以下における光線透過率を、ＪＩＳ　Ｋ７３６１  １に準拠して、（株）村上色彩技術研究所製のヘイズメーターＨＭ１５０を用いて測定した。 (2) Light transmittance at wavelengths of 400 nm or more and 1200 nm or less The light transmittance of the resin film for current collector sheet at wavelengths of 400 nm or more and 1200 nm or less was measured using a haze meter manufactured by Murakami Color Research Institute Co., Ltd. in accordance with JIS K7361 1. Measured using HM150.
（３）ヘイズ
　集電シート用樹脂フィルムを５０ｍｍ×５０ｍｍにカットし、試験片を作製した。次いで、ＥＴＦＥ（テトラフルオロエチレン－エチレン共重合体）フィルムと試験片とＥＴＦＥフィルムとをこの順に積層し、設定温度１６５℃、真空引き２分、プレス２．５分、圧力１００ｋＰａの条件で真空ラミネートを行った。続いて、試験片の両面からそれぞれＥＴＦＥフィルムを除去し、測定用サンプルを得た。そして、測定用サンプルのヘイズを、ＪＩＳ　Ｋ７１３６に準拠して、（株）村上色彩技術研究所製のヘイズメーターＨＭ１５０を用いて測定した。 (3) Haze A test piece was prepared by cutting a resin film for a current collector sheet into a size of 50 mm x 50 mm. Next, the ETFE (tetrafluoroethylene-ethylene copolymer) film, the test piece, and the ETFE film were laminated in this order, and vacuum laminated at a set temperature of 165°C, vacuuming for 2 minutes, pressing for 2.5 minutes, and pressure of 100 kPa. I did it. Subsequently, the ETFE film was removed from both sides of the test piece to obtain a measurement sample. Then, the haze of the measurement sample was measured in accordance with JIS K7136 using a haze meter HM150 manufactured by Murakami Color Research Institute.
（４）ワイヤ密着性
　ワイヤとして、ＳｎＩｎ系はんだで被覆されているワイヤＡおよびＳｎＢｉ系はんだで被覆されているワイヤＢを用いた。ワイヤＡおよびワイヤＢの直径はそれぞれ、２５０μｍであった。集電シート用樹脂フィルムを１００ｍｍ×１００ｍｍにカットし、試験片を作製した。次いで、試験片の基材層側の面に、ＥＴＦＥ（テトラフルオロエチレン－エチレン共重合体）フィルムを配置した。また、試験片のポリエチレン樹脂層側の面に、ワイヤＡおよびワイヤＢを１０ｍｍピッチの間隔をあけてそれぞれ５本ずつと、ＥＴＦＥフィルムとを順に配置した。その後、設定温度１２０℃、プレス圧力０．１ＭＰａの条件で熱ロールラミネーターを用いてラミネートを行った。続いて、試験片の両面からそれぞれＥＴＦＥフィルムを除去し、評価用サンプルを得た。そして、評価用サンプルのワイヤを１８０度屈曲させて、引張速度３００ｍｍ／ｍｉｎの条件で集電シート用樹脂フィルムから剥離し、集電シート用樹脂フィルムからの集電ワイヤの剥離強度を測定した。ワイヤ密着性は、下記基準にて評価した。なお、「Ｎ／ワイヤ」とは、ワイヤ１本を剥離した際の剥離強度を示している。
Ａ：剥離強度が０．１Ｎ／ワイヤ超である。
Ｂ：集電シート用樹脂フィルムにワイヤが密着するが、剥離強度が０．１Ｎ／ワイヤ以下である。
Ｃ：集電シート用樹脂フィルムにワイヤが密着せず自然剥離する。 (4) Wire Adhesion Wire A coated with SnIn-based solder and Wire B coated with SnBi-based solder were used as wires. The diameters of wire A and wire B were each 250 μm. A test piece was prepared by cutting the resin film for current collector sheet into a size of 100 mm x 100 mm. Next, an ETFE (tetrafluoroethylene-ethylene copolymer) film was placed on the surface of the test piece on the base layer side. Further, on the polyethylene resin layer side surface of the test piece, five wires A and five wires B each at a pitch of 10 mm and an ETFE film were arranged in this order. Thereafter, lamination was performed using a hot roll laminator under conditions of a set temperature of 120° C. and a press pressure of 0.1 MPa. Subsequently, the ETFE film was removed from both sides of the test piece to obtain a sample for evaluation. Then, the wire of the evaluation sample was bent 180 degrees and peeled from the resin film for current collector sheet under conditions of a tensile speed of 300 mm/min, and the peel strength of the current collector wire from the resin film for current collector sheet was measured. Wire adhesion was evaluated based on the following criteria. Note that "N/wire" indicates the peel strength when one wire is peeled off.
A: Peel strength is more than 0.1 N/wire.
B: The wire adheres closely to the resin film for current collector sheet, but the peel strength is 0.1 N/wire or less.
C: The wire did not adhere to the resin film for current collector sheet and naturally peeled off.
（５）モジュール信頼性
　まず、上記のワイヤ密着性の評価における評価用サンプルの作製方法と同様にして、集電シート用樹脂フィルムにワイヤが固定された集電シートを得た。この際、試験片のポリエチレン樹脂層側の面には、８ｍｍピッチで計１８本のワイヤを配置した。なお、ワイヤ密着性の評価が「Ｃ」であったサンプルについては、熱ロールラミネーターでの設定温度を１３０℃に上げることで、ワイヤ密着性を担保した。 (5) Module Reliability First, a current collector sheet in which wires were fixed to a resin film for a current collector sheet was obtained in the same manner as the method for preparing the evaluation sample in the wire adhesion evaluation described above. At this time, a total of 18 wires were arranged at a pitch of 8 mm on the surface of the test piece on the polyethylene resin layer side. Note that for the samples whose wire adhesion was evaluated as "C", wire adhesion was ensured by increasing the set temperature of the hot roll laminator to 130°C.
　透明基板として、厚さ３．２ｍｍの白板強化ガラスを用い、第１封止材および第２封止材として、厚さ４７０μｍのエチレン－酢酸ビニル共重合体（ＥＶＡ）シート（タキロンシーアイ社製、ファストキュアＥＶＡ）を用い、太陽電池素子として、Ｎ型シリコンセルを用い、対向基板として、アルミニウム層含有バックシート（大日本印刷社製、ＶＡＰＥ－ＣＷ）を用いた。次に、透明基板と、第１封止材と、集電シートと、太陽電池素子と、集電シートと、第２封止材と、対向基板とを積層し、設定温度１５０℃、真空引き５分、プレス７．５分、圧力１００ｋＰａの条件で真空ラミネートを行った。なお、各部材を積層する際には、集電シートを、集電シートのワイヤ側の面が太陽電池素子側を向くように配置した。また、この際、図３（ｂ）に例示するように、集電シート２０を太陽電池素子３１の上下に配置していくことで、４つの太陽電池素子を直列接合した太陽電池モジュールとして評価用モジュールを作製した。 A white tempered glass sheet with a thickness of 3.2 mm was used as the transparent substrate, and an ethylene-vinyl acetate copolymer (EVA) sheet with a thickness of 470 μm (manufactured by Takiron CI Co., Ltd., Fast Cure EVA) was used, an N-type silicon cell was used as the solar cell element, and an aluminum layer-containing backsheet (VAPE-CW, manufactured by Dainippon Printing Co., Ltd.) was used as the counter substrate. Next, the transparent substrate, the first encapsulant, the current collector sheet, the solar cell element, the current collector sheet, the second encapsulant, and the counter substrate are laminated, and the temperature is set to 150°C and vacuum is applied. Vacuum lamination was performed under the conditions of 5 minutes, pressing 7.5 minutes, and pressure 100 kPa. In addition, when laminating each member, the current collecting sheet was arranged so that the surface on the wire side of the current collecting sheet faced the solar cell element side. At this time, as illustrated in FIG. 3(b), by arranging the current collector sheets 20 above and below the solar cell elements 31, a solar cell module in which four solar cell elements are connected in series can be used for evaluation. A module was created.
　評価用モジュールについて、高温高湿試験（８５℃、８５％ＲＨ、２０００時間）、および、温度サイクル試験（－４０℃⇔９０℃、２００サイクル、１サイクル＝６時間）をそれぞれ実施した。各試験前後の光起電力の出力を測定し、出力低下率を求めた。モジュール信頼性は、下記基準にて評価した。
Ａ：両方の試験後の出力低下率が５％未満である。
Ｂ：少なくとも一方の試験後の出力低下率が５％以上１０％未満である。
Ｃ：少なくとも一方の試験後の出力低下率が１０％以上である。 A high temperature and high humidity test (85°C, 85% RH, 2000 hours) and a temperature cycle test (-40°C⇔90°C, 200 cycles, 1 cycle = 6 hours) were conducted on the evaluation module. The photovoltaic output before and after each test was measured, and the output reduction rate was determined. Module reliability was evaluated based on the following criteria.
A: The output reduction rate after both tests is less than 5%.
B: The output reduction rate after at least one test is 5% or more and less than 10%.
C: The output reduction rate after at least one test is 10% or more.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　表１から、集電シート用樹脂フィルムにおけるポリエチレン樹脂層のＭＦＲが所定の範囲内であり、集電シート用樹脂フィルムの熱収縮率が所定の範囲内である場合には、ワイヤ密着性およびモジュール信頼性が良好であることが確認された。 From Table 1, when the MFR of the polyethylene resin layer in the resin film for current collector sheet is within a predetermined range and the heat shrinkage rate of the resin film for current collector sheet is within a predetermined range, wire adhesion and module It was confirmed that reliability was good.
　また、比較例１、４では、温度サイクル試験後に出力が低下した。これは、集電シート用樹脂フィルムの熱収縮率が高いと、モジュールラミネート後の残留応力が高くなるためである。 Furthermore, in Comparative Examples 1 and 4, the output decreased after the temperature cycle test. This is because if the resin film for the current collector sheet has a high thermal shrinkage rate, the residual stress after module lamination will increase.
　なお、実施例１および比較例４において基材層として用いたＰＥＴフィルム単体についても、集電シート用樹脂フィルムと同様に熱収縮率を測定したところ、ＭＤ方向の熱収縮率は１．４％、ＴＤ方向の熱収縮率は０．３％であった。このことから、基材層自体の熱収縮率が２．０％以下であっても、集電シート用樹脂フィルム全体の熱収縮率が２．０％以下になるとは限らないことが示唆された。 In addition, when the heat shrinkage rate of the PET film alone used as the base layer in Example 1 and Comparative Example 4 was measured in the same manner as the resin film for current collector sheet, the heat shrinkage rate in the MD direction was 1.4%. , the heat shrinkage rate in the TD direction was 0.3%. This suggests that even if the heat shrinkage rate of the base layer itself is 2.0% or less, the heat shrinkage rate of the entire resin film for current collector sheet is not necessarily 2.0% or less. .
［実施例３］
　保護層および透明バリア層を有するバリアフィルムとして、厚さ１２μｍのポリエチレンテレフタレート（ＰＥＴ）フィルムの一方の面に厚さ１０ｎｍの酸化ケイ素蒸着膜が形成されたバリアフィルム（三菱ケミカル社製「テックバリア Ｔｅｃｈ ＬＸ」）を用いた。また、接着剤として、ポリカーボネート系の主剤（ロックペイント社製「ＫＴ－００３５」）と、イソシアネート系の硬化剤（ロックペイント社製「Ｈ－０３９Ｚ２」）とからなる２液型接着剤を用いた。また、ポリエチレン樹脂として、低密度ポリエチレン（ＬＤＰＥ）（住友化化学社製「スミカセンＣＥ４００９」）を用いた。また、透明基材として、厚さ１２μｍのポリエチレンテレフタレート（ＰＥＴ）フィルム（デュポン社製「ＬＢＤ」）を用いた。 [Example 3]
As a barrier film having a protective layer and a transparent barrier layer, a barrier film in which a 10 nm thick silicon oxide vapor deposited film was formed on one side of a 12 μm thick polyethylene terephthalate (PET) film (“Tech Barrier Tech” manufactured by Mitsubishi Chemical Corporation) was used. LX") was used. In addition, a two-component adhesive consisting of a polycarbonate base agent (KT-0035 manufactured by Rock Paint Co., Ltd.) and an isocyanate curing agent (H-039Z2 manufactured by Rock Paint Co., Ltd.) was used as the adhesive. . Moreover, low density polyethylene (LDPE) ("Sumikasen CE4009" manufactured by Sumitomo Chemical Co., Ltd.) was used as the polyethylene resin. Moreover, a polyethylene terephthalate (PET) film ("LBD" manufactured by DuPont) with a thickness of 12 μm was used as a transparent base material.
　上記透明基材の片面に上記接着剤を厚さ５μｍで塗布し、上記バリアフィルムの酸化ケイ素蒸着膜側の面とドライラミネート法を用いて貼り合わせを行った。続いて、接着剤硬化のために、４５℃、５日間のエージングを行った。次に、上記バリアフィルムの保護層側の面に、上記接着剤をアンカー剤として塗布し、ポリエチレン樹脂を厚さ６０μｍで押し出して、封止層を形成した。さらに、上記封止層のバリアフィルムとは反対側の面にコロナ処理を施した。これにより、透明基材と、第２の接着層と、透明バリア層と、保護層と、接着層と、封止層とをこの順に有する集電シート用フィルムを得た。 The adhesive was applied to a thickness of 5 μm on one side of the transparent substrate, and the adhesive was bonded to the silicon oxide vapor-deposited film side of the barrier film using a dry lamination method. Subsequently, aging was performed at 45° C. for 5 days to cure the adhesive. Next, the adhesive was applied as an anchor to the surface of the barrier film on the protective layer side, and polyethylene resin was extruded to a thickness of 60 μm to form a sealing layer. Further, the surface of the sealing layer opposite to the barrier film was subjected to corona treatment. Thereby, a film for a current collector sheet having a transparent base material, a second adhesive layer, a transparent barrier layer, a protective layer, an adhesive layer, and a sealing layer in this order was obtained.
［実施例４］
　下記のようにしてバリアフィルムを作製したこと以外は、実施例３と同様にして、集電シート用フィルムを作製した。これにより、透明基材と、第２の接着層と、オーバーコート層と、透明バリア層と、保護層と、接着層と、封止層とをこの順に有する集電シート用フィルムを得た。 [Example 4]
A current collector sheet film was produced in the same manner as in Example 3, except that the barrier film was produced as described below. Thereby, a film for a current collector sheet having a transparent base material, a second adhesive layer, an overcoat layer, a transparent barrier layer, a protective layer, an adhesive layer, and a sealing layer in this order was obtained.
　透明基材および透明バリア層を有するフィルムとして、厚さ１２μｍのポリエチレンテレフタレート（ＰＥＴ）フィルムの一方の面に厚さ１０ｎｍの酸化ケイ素蒸着膜（透明バリア層）が形成されたフィルム（三菱ケミカル社製「テックバリア　Ｔｅｃｈ　ＬＸ」）を用いた。 As a film having a transparent base material and a transparent barrier layer, a film (manufactured by Mitsubishi Chemical Corporation) in which a 10 nm thick silicon oxide vapor deposited film (transparent barrier layer) was formed on one side of a 12 μm thick polyethylene terephthalate (PET) film was used. "Tech Barrier Tech LX") was used.
　また、オーバーコート層を形成するための樹脂組成物を調製した。具体的には、下記組成のＡ液に、下記組成のＢ液を加えて撹拌し、ゾルゲル法によりオーバーコート層用樹脂組成物を得た。 Additionally, a resin composition for forming an overcoat layer was prepared. Specifically, Solution B having the following composition was added to Solution A having the following composition and stirred to obtain a resin composition for an overcoat layer by a sol-gel method.
＜Ａ液：混合液＞
ポリビニルアルコール（ＰＶＡ）　１．８１質量部
イソプロピルアルコール　３９．８質量部
イオン交換水　２．０９質量部 <Liquid A: Mixed liquid>
Polyvinyl alcohol (PVA) 1.81 parts by mass Isopropyl alcohol 39.8 parts by mass Ion exchange water 2.09 parts by mass
＜Ｂ液：加水分解液＞
オルトケイ酸テトラエチル（ＴＥＯＳ）　２１．４９質量部
イソプロピルアルコール　５．０３質量部
０．５Ｎ塩酸水溶液　０．６９質量部
イオン交換水　２９．１質量部 <Liquid B: Hydrolyzed liquid>
Tetraethyl orthosilicate (TEOS) 21.49 parts by mass Isopropyl alcohol 5.03 parts by mass 0.5N aqueous hydrochloric acid solution 0.69 parts by mass Ion exchange water 29.1 parts by mass
　上記フィルムの透明バリア層上に、上記樹脂組成物を塗布し、１５０℃で３０秒間加熱乾燥し、２００℃で３０秒間加熱処理を行った。これにより、透明基材と透明バリア層とオーバーコート層とをこの順に有するバリアフィルムを得た。 The resin composition was applied onto the transparent barrier layer of the film, dried by heating at 150°C for 30 seconds, and heat-treated at 200°C for 30 seconds. Thereby, a barrier film having a transparent base material, a transparent barrier layer, and an overcoat layer in this order was obtained.
［比較例５］
　透明基材として、厚さ１２μｍのポリエチレンテレフタレート（ＰＥＴ）フィルム（デュポン社製「ＬＢＤ」）を用いた。また、接着剤として、ポリカーボネート系の主剤（ロックペイント社製「ＫＴ－００３５」）と、イソシアネート系の硬化剤（ロックペイント社製「Ｈ－０３９Ｚ２」）とからなる２液型接着剤を用いた。また、ポリエチレン樹脂として、低密度ポリエチレン（ＬＤＰＥ）（住友化化学社製「スミカセンＣＥ４００９」）を用いた。 [Comparative example 5]
A 12 μm thick polyethylene terephthalate (PET) film (“LBD” manufactured by DuPont) was used as the transparent base material. In addition, a two-component adhesive consisting of a polycarbonate base agent (KT-0035 manufactured by Rock Paint Co., Ltd.) and an isocyanate curing agent (H-039Z2 manufactured by Rock Paint Co., Ltd.) was used as the adhesive. . Moreover, low density polyethylene (LDPE) ("Sumikasen CE4009" manufactured by Sumitomo Chemical Co., Ltd.) was used as the polyethylene resin.
　上記透明基材の片面に、上記接着剤をアンカー剤として塗布し、上記ポリエチレン樹脂を厚さ６０μｍで押し出して、ポリエチレン樹脂を含む封止層を形成した。さらに、封止層の透明基材とは反対側の面にコロナ処理を施した。これにより、透明基材と接着層と封止層とをこの順に有する集電シート用フィルムを得た。 The adhesive was applied as an anchor to one side of the transparent base material, and the polyethylene resin was extruded to a thickness of 60 μm to form a sealing layer containing polyethylene resin. Furthermore, the surface of the sealing layer opposite to the transparent base material was subjected to corona treatment. Thereby, a film for a current collector sheet having a transparent base material, an adhesive layer, and a sealing layer in this order was obtained.
［参考例１］
　厚さ５０μｍの白色ＰＥＴフィルム（デュポン社製「Ｓ－ＰＶ８Ｗ」）と、厚さ７μｍのアルミニウム箔と、厚さ２５０μｍの透明ＰＥＴフィルム（デュポン社製「Ｍｙｌａｒ　Ａ　Ｓ６」）と、厚さ３０μｍのポリエチレンフィルム（タマポリ社製「ＳＥ６２５ＮＷＴ０２」、白色ＬＬＤＰＥ）とがこの順に、接着剤を介して積層された、裏面保護シートＡを準備した。 [Reference example 1]
A 50 μm thick white PET film (“S-PV8W” manufactured by DuPont), a 7 μm thick aluminum foil, a 250 μm thick transparent PET film (“Mylar A S6” manufactured by DuPont), and a 30 μm thick A back protection sheet A was prepared in which polyethylene films ("SE625NWT02" manufactured by Tamapori Co., Ltd., white LLDPE) were laminated in this order via an adhesive.
［参考例２］
　厚さ１４０μｍの透明ＰＥＴフィルム（デュポン社製「ＡＰ」）と、実施例２で用いたバリアフィルムと、厚さ１４０μｍの透明ＰＥＴフィルム（デュポン社製「ＡＰ」）と、実施例２で用いたバリアフィルムとがこの順に、接着剤を介して積層され、さらに、透明ＰＥＴフィルム側の面に、厚さ５μｍのアクリル系樹脂をベースとする耐候性トップコート層が形成され、バリアフィルム側の面に厚さ１μｍの易接着プライマー層が形成された、裏面保護シートＢを準備した。 [Reference example 2]
A 140 μm thick transparent PET film (“AP” manufactured by DuPont), a barrier film used in Example 2, a 140 μm thick transparent PET film (“AP” manufactured by DuPont), and a barrier film used in Example 2. A barrier film is laminated in this order via an adhesive, and then a weather-resistant top coat layer based on an acrylic resin with a thickness of 5 μm is formed on the surface on the transparent PET film side. A back protection sheet B was prepared, on which an easily adhesive primer layer with a thickness of 1 μm was formed.
［参考例３］
　厚さ１５２μｍの白色ＰＥＴフィルム（デュポン社製「ＢＰ」）と、厚さ３０μｍのポリエチレンフィルム（タマポリ社製「ＳＥ６２５Ｎ」、白色ＬＬＤＰＥ）とがこの順に、接着剤を介して積層された、裏面保護シートＣを準備した。 [Reference example 3]
Back protection in which a 152 μm thick white PET film (“BP” manufactured by DuPont) and a 30 μm thick polyethylene film (“SE625N” manufactured by Tamapori, white LLDPE) are laminated in this order via adhesive. Sheet C was prepared.
［製造例１］
　基材層として、厚さ１５２μｍの耐加水分解性を有するポリエチレンテレフタレート（ＰＥＴ）フィルム（デュポン社製「ＢＰ」）を用いた。また、易接着層として、厚さ３０μｍのポリエチレンフィルム（タマポリ社製「ＳＥ６２５Ｎ」）を用いた。また、接着剤として、ポリカーボネート系の主剤（ロックペイント社製「ＫＴ－００３５」）と、イソシアネート系の硬化剤（ロックペイント社製「Ｈ－０３９Ｚ２」）とからなる２液型接着剤を用いた。 [Manufacture example 1]
As the base material layer, a polyethylene terephthalate (PET) film ("BP" manufactured by DuPont) having a thickness of 152 μm and having hydrolysis resistance was used. In addition, a 30 μm thick polyethylene film (“SE625N” manufactured by Tamapoly Co., Ltd.) was used as an easily adhesive layer. In addition, a two-component adhesive consisting of a polycarbonate base agent (KT-0035 manufactured by Rock Paint Co., Ltd.) and an isocyanate curing agent (H-039Z2 manufactured by Rock Paint Co., Ltd.) was used as the adhesive. .
　ドライラミネート法により、基材層と易接着層とを接着剤を介して積層した。これにより、基材層と第３の接着層と易接着層とをこの順に有する裏面保護シートＤを得た。 A base material layer and an easily adhesive layer were laminated via an adhesive by a dry lamination method. Thereby, a back protection sheet D having a base material layer, a third adhesive layer, and an easy-to-adhesion layer in this order was obtained.
［製造例２］
　基材層として、厚さ１５２μｍの耐加水分解性を有するポリエチレンテレフタレート（ＰＥＴ）フィルム（デュポン社製「ＢＰ」）を用いた。また、第２のバリアフィルムとして、実施例２で用いた、透明基材と透明バリア層とオーバーコート層とをこの順に有するバリアフィルムを用いた。また、易接着層として、厚さ３０μｍのポリエチレンフィルム（タマポリ社製「ＳＥ６２５Ｎ」）を用いた。また、接着剤として、ポリカーボネート系の主剤（ロックペイント社製「ＫＴ－００３５」）と、イソシアネート系の硬化剤（ロックペイント社製「Ｈ－０３９Ｚ２」）とからなる２液型接着剤を用いた。 [Manufacture example 2]
As the base material layer, a polyethylene terephthalate (PET) film ("BP" manufactured by DuPont) having a thickness of 152 μm and having hydrolysis resistance was used. Further, as the second barrier film, the barrier film used in Example 2 and having a transparent base material, a transparent barrier layer, and an overcoat layer in this order was used. In addition, a 30 μm thick polyethylene film (“SE625N” manufactured by Tamapoly Co., Ltd.) was used as an easily adhesive layer. In addition, a two-component adhesive consisting of a polycarbonate base agent (KT-0035 manufactured by Rock Paint Co., Ltd.) and an isocyanate curing agent (H-039Z2 manufactured by Rock Paint Co., Ltd.) was used as the adhesive. .
　ドライラミネート法により、基材層と第２のバリアフィルムと易接着層とをそれぞれ接着剤を介して積層した。これにより、基材層と第３の接着層と第２のバリアフィルムと第４の接着層と易接着層とをこの順に有する裏面保護シートＥを得た。第２のバリアフィルムは、透明基材が易接着層側、オーバーコート層が基材層側になるように配置した。 The base material layer, the second barrier film, and the easy-to-adhesion layer were each laminated via an adhesive by a dry lamination method. Thereby, a back protection sheet E was obtained which had a base material layer, a third adhesive layer, a second barrier film, a fourth adhesive layer, and an easily adhesive layer in this order. The second barrier film was arranged so that the transparent base material was on the easily adhesive layer side and the overcoat layer was on the base layer side.
［評価２］
（１）水蒸気透過度
　集電シート用フィルムおよび裏面保護シートについて、ＩＳＯ　１５１０６－５：２０１５（差圧法）に準拠して、水蒸気透過度測定装置（Ｔｅｃｈｎｏｌｏｘ社製の「ＤＥＬＴＡＰＥＲＭ」）を用いて、温度４０℃、相対湿度差９０％ＲＨの条件で、水蒸気透過度を測定した。 [Evaluation 2]
(1) Water vapor permeability The current collector sheet film and back protection sheet were measured using a water vapor permeability measuring device (“DELTAPERM” manufactured by Technolox) in accordance with ISO 15106-5:2015 (differential pressure method). Water vapor permeability was measured under conditions of a temperature of 40° C. and a relative humidity difference of 90% RH.
（２）バリア性
　まず、集電シート用フィルムおよび裏面保護シートを用いて、試験用太陽電池モジュールを作製した。具体的には、透明基板として、厚さ３．２ｍｍの白板強化ガラスを用い、第１封止材および第２封止材として厚さ４７０μｍのエチレン－酢酸ビニル共重合体（ＥＶＡ）シート（タキロンシーアイ社製、ファストキュアＥＶＡ）を用いた。次いで、透明基板と、第１封止材と、集電シート用フィルムと、塩化コバルト紙と、集電シート用フィルムと、第２封止材と、裏面保護シートとを、この順に積層し、設定温度１５０℃、真空引き５分、プレス７．５分、圧力１００ｋＰａの条件で真空ラミネートを行い、試験用太陽電池モジュールを作製した。塩化コバルト紙（アドバンテック東洋社製）は、予め８０℃のオーブンで乾燥させて用いた。 (2) Barrier properties First, a test solar cell module was produced using a current collector sheet film and a back protection sheet. Specifically, a 3.2 mm thick white tempered glass plate was used as the transparent substrate, and a 470 μm thick ethylene-vinyl acetate copolymer (EVA) sheet (Takiron) was used as the first and second sealing materials. Fast Cure EVA) manufactured by CI Corporation was used. Next, the transparent substrate, the first sealing material, the current collecting sheet film, the cobalt chloride paper, the current collecting sheet film, the second sealing material, and the back protection sheet are laminated in this order, Vacuum lamination was performed under the conditions of a set temperature of 150° C., evacuation for 5 minutes, press for 7.5 minutes, and pressure of 100 kPa to produce a test solar cell module. Cobalt chloride paper (manufactured by Advantech Toyo Co., Ltd.) was used after being dried in an oven at 80°C.
　次に、試験用太陽電池モジュールに対して、高温高湿試験を実施した。高温高湿試験は、試験用太陽電池モジュールを、温度８５℃、湿度８５％ＲＨに設定したオーブンに投入して行い、１２時間、２４時間、７２時間、９６時間、１２０時間経過後における塩化コバルト紙の呈色を目視により観察した。 Next, a high temperature and high humidity test was conducted on the test solar cell module. The high temperature and high humidity test was conducted by placing the test solar cell module in an oven set at a temperature of 85°C and a humidity of 85% RH. The coloration of the paper was visually observed.
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
　表２および表３から、集電シート用フィルムがバリアフィルムを有する場合には、バリア性が良好であることが確認された。特に、集電シート用フィルムおよび裏面保護シートの両方がバリアフィルムを有する場合（試験番号８、９）には、裏面保護シートがアルミニウム箔を有する場合（試験番号１）や、裏面保護シートが、水蒸気バリア性に優れ高価なバリアフィルムである場合（試験番号２）と、同程度の高温高湿試験結果が得られることが示された。 From Tables 2 and 3, it was confirmed that when the current collector sheet film had a barrier film, the barrier properties were good. In particular, when both the current collector sheet film and the back protection sheet have a barrier film (test numbers 8 and 9), when the back protection sheet has aluminum foil (test number 1), or when the back protection sheet has a barrier film, It was shown that similar high temperature and high humidity test results could be obtained as in the case of an expensive barrier film with excellent water vapor barrier properties (Test No. 2).
　本開示は、以下の発明を提供する。
［１］太陽電池の集電シートに用いられる集電シート用樹脂フィルムであって、
　基材層と、接着層と、ポリエチレン樹脂層と、をこの順に有し、
　上記基材層が、ポリエチレンテレフタレート樹脂を含有し、
　上記ポリエチレン樹脂層の１９０℃におけるメルトマスフローレートが、４ｇ／１０分以上８ｇ／１０分以下であり、
　１５０℃で１０分間保持したときの熱収縮率が、２．０％以下である、集電シート用樹脂フィルム。
［２］上記ポリエチレン樹脂層の融点が、１００℃以上１２０℃以下である、［１］に記載の集電シート用樹脂フィルム。
［３］上記ポリエチレン樹脂層の厚さが、上記基材層の厚さよりも厚い、［１］または［２］に記載の集電シート用樹脂フィルム。
［４］上記ポリエチレン樹脂層の厚さが、４０μｍ以上１００μｍ以下である、［１］から［３］までのいずれかに記載の集電シート用樹脂フィルム。
［５］上記基材層の厚さが、１２μｍ以上３８μｍ以下である、［１］から［４］までのいずれかに記載の集電シート用樹脂フィルム。
［６］上記接着層の厚さが、０．１μｍ以上１０μｍ以下である、［１］から［５］までのいずれかに記載の集電シート用樹脂フィルム。
［７］上記基材層が、上記接着層とは反対の面に、表面処理部を有する、［１］から［６］までのいずれかに記載の集電シート用樹脂フィルム。
［８］太陽電池の集電シートに用いられる集電シート用フィルムであって、
　透明基材と、透明バリア層と、接着層と、封止層と、をこの順に有する、集電シート用フィルム。
［９］上記透明バリア層と上記接着層との間に、保護層を有する、［８］に記載の集電シート用フィルム。
［１０］上記透明バリア層と上記接着層との間に、オーバーコート層を有する、［８］または［９］に記載の集電シート用フィルム。
［１１］水蒸気透過度が、１×１０－３ｇ／（ｍ２・ｄａｙ）以上１ｇ／（ｍ２・ｄａｙ）以下である、［８］から［１０］までのいずれかに記載の集電シート用フィルム。
［１２］上記封止層が、ポリオレフィン樹脂を含有する、［８］から［１１］までのいずれかに記載の集電シート用フィルム。
［１３］上記ポリオレフィン樹脂が、ポリエチレン樹脂である、［１２］に記載の集電シート用フィルム。
［１４］上記封止層が、上記接着層とは反対の面に、表面処理部を有する、［８］から［１３］までのいずれかに記載の集電シート用フィルム。
［１５］太陽電池に用いられる集電シートであって、
　［１］から［７］までのいずれかに記載の集電シート用樹脂フィルムと、
　上記集電シート用樹脂フィルムの上記ポリエチレン樹脂層の面側に配置されたワイヤと、
　を有する、集電シート。
［１６］太陽電池に用いられる集電シートであって、
　［８］から［１４］までのいずれかに記載の集電シート用フィルムと、
　上記集電シート用フィルムの上記封止層の面側に配置されたワイヤと、
　を有する、集電シート。
［１７］［１５］に記載の集電シートと、
　上記集電シートの上記ポリエチレン樹脂層の面側に配置され、上記ワイヤと電気的に接続された太陽電池素子と、
　を有する、集電シート付き太陽電池素子。
［１８］［１６］に記載の集電シートと、
　上記集電シートの上記封止層の面側に配置され、上記ワイヤと電気的に接続された太陽電池素子と、
　を有する、集電シート付き太陽電池素子。
［１９］透明基板と、第１封止材と、［１７］に記載の集電シート付き太陽電池素子と、第２封止材と、対向基板と、をこの順に有する、太陽電池。
［２０］透明基板と、第１封止材と、［１８］に記載の集電シート付き太陽電池素子と、第２封止材と、裏面保護シートと、をこの順に有する、太陽電池。
［２１］上記太陽電池は、複数の上記集電シート付き太陽電池素子を有する太陽電池モジュールである、［１９］に記載の太陽電池。
［２２］上記太陽電池は、複数の上記集電シート付き太陽電池素子を有する太陽電池モジュールである、［２０］に記載の太陽電池。
［２３］上記裏面保護シートが、上記第２封止材側から順に、易接着層と、バリアフィルムと、基材層とを有する、［２０］または［２２］に記載の太陽電池。 The present disclosure provides the following inventions.
[1] A resin film for a current collector sheet used in a current collector sheet of a solar cell,
It has a base material layer, an adhesive layer, and a polyethylene resin layer in this order,
The base layer contains polyethylene terephthalate resin,
The polyethylene resin layer has a melt mass flow rate at 190° C. of 4 g/10 minutes or more and 8 g/10 minutes or less,
A resin film for a current collector sheet, which has a heat shrinkage rate of 2.0% or less when held at 150°C for 10 minutes.
[2] The resin film for a current collector sheet according to [1], wherein the polyethylene resin layer has a melting point of 100°C or more and 120°C or less.
[3] The resin film for a current collector sheet according to [1] or [2], wherein the polyethylene resin layer is thicker than the base layer.
[4] The resin film for a current collector sheet according to any one of [1] to [3], wherein the polyethylene resin layer has a thickness of 40 μm or more and 100 μm or less.
[5] The resin film for a current collector sheet according to any one of [1] to [4], wherein the base layer has a thickness of 12 μm or more and 38 μm or less.
[6] The resin film for a current collector sheet according to any one of [1] to [5], wherein the adhesive layer has a thickness of 0.1 μm or more and 10 μm or less.
[7] The resin film for a current collector sheet according to any one of [1] to [6], wherein the base layer has a surface-treated portion on a surface opposite to the adhesive layer.
[8] A film for a current collector sheet used for a current collector sheet of a solar cell,
A film for a current collector sheet, comprising a transparent base material, a transparent barrier layer, an adhesive layer, and a sealing layer in this order.
[9] The film for a current collector sheet according to [8], which has a protective layer between the transparent barrier layer and the adhesive layer.
[10] The film for a current collector sheet according to [8] or [9], which has an overcoat layer between the transparent barrier layer and the adhesive layer.
[11] The current collector according to any one of [8] to [10], which has a water vapor permeability of 1×10 −3 g/(m 2 ·day) or more and 1 g/(m 2 ·day) or less. Film for sheets.
[12] The film for a current collector sheet according to any one of [8] to [11], wherein the sealing layer contains a polyolefin resin.
[13] The film for a current collector sheet according to [12], wherein the polyolefin resin is a polyethylene resin.
[14] The film for a current collector sheet according to any one of [8] to [13], wherein the sealing layer has a surface treatment portion on a surface opposite to the adhesive layer.
[15] A current collector sheet used for solar cells,
The resin film for current collector sheet according to any one of [1] to [7],
A wire arranged on the surface side of the polyethylene resin layer of the resin film for current collector sheet;
A current collecting sheet having.
[16] A current collector sheet used in solar cells,
The film for current collector sheet according to any one of [8] to [14],
A wire arranged on the surface side of the sealing layer of the current collector sheet film;
A current collecting sheet having.
[17] The current collector sheet according to [15],
a solar cell element arranged on the surface side of the polyethylene resin layer of the current collector sheet and electrically connected to the wire;
A solar cell element with a current collecting sheet.
[18] The current collector sheet according to [16],
a solar cell element arranged on the surface side of the sealing layer of the current collector sheet and electrically connected to the wire;
A solar cell element with a current collecting sheet.
[19] A solar cell comprising, in this order, a transparent substrate, a first encapsulant, the solar cell element with a current collector sheet according to [17], a second encapsulant, and a counter substrate.
[20] A solar cell comprising, in this order, a transparent substrate, a first encapsulant, the solar cell element with a current collector sheet according to [18], a second encapsulant, and a back protection sheet.
[21] The solar cell according to [19], wherein the solar cell is a solar cell module having a plurality of the solar cell elements with the current collector sheet.
[22] The solar cell according to [20], wherein the solar cell is a solar cell module having a plurality of the solar cell elements with the current collector sheet.
[23] The solar cell according to [20] or [22], wherein the back protection sheet includes, in order from the second sealing material side, an easily adhesive layer, a barrier film, and a base layer.
　　１　…　基材層
　　２　…　接着層
　　３　…　ポリエチレン樹脂層
　　１０、１０Ａ、１０Ｂ　…　集電シート用樹脂フィルム
　　１１　…　ワイヤ
　　２０　…　集電シート
　　３０　…　集電シート付き太陽電池素子
　　３１　…　太陽電池素子
　　４０　…　太陽電池
　　４１　…　透明基板
　　４２　…　第１封止材
　　４３　…　第２封止材
　　４４　…　対向基板
　　５０　…　集電シート用フィルム
　　５１　…　透明基材
　　５２　…　透明バリア層
　　５３　…　接着層
　　５４　…　封止層
　　５５　…　バリアフィルム
　　５６　…　保護層
　　５７　…　オーバーコート層 1... Base material layer 2... Adhesive layer 3... Polyethylene resin layer 10, 10A, 10B... Resin film for current collector sheet 11... Wire 20... Current collector sheet 30... Solar cell element with current collector sheet 31... Solar cell element 40... Solar cell 41... Transparent substrate 42... First sealing material 43... Second sealing material 44... Counter substrate 50... Film for current collector sheet 51... Transparent base material 52... Transparent barrier layer 53... Adhesive layer 54... Sealing layer 55... Barrier film 56... Protective layer 57... Overcoat layer

Claims (23)

  1. 　太陽電池の集電シートに用いられる集電シート用樹脂フィルムであって、
    　基材層と、接着層と、ポリエチレン樹脂層と、をこの順に有し、
    　前記基材層が、ポリエチレンテレフタレート樹脂を含有し、
    　前記ポリエチレン樹脂層の１９０℃におけるメルトマスフローレートが、４ｇ／１０分以上８ｇ／１０分以下であり、
    　１５０℃で１０分間保持したときの熱収縮率が、２．０％以下である、集電シート用樹脂フィルム。     A resin film for a current collector sheet used for a current collector sheet of a solar cell,
    It has a base material layer, an adhesive layer, and a polyethylene resin layer in this order,
    The base material layer contains polyethylene terephthalate resin,
    The polyethylene resin layer has a melt mass flow rate at 190° C. of 4 g/10 minutes or more and 8 g/10 minutes or less,
    A resin film for a current collector sheet, which has a heat shrinkage rate of 2.0% or less when held at 150°C for 10 minutes.
  2. 　前記ポリエチレン樹脂層の融点が、１００℃以上１２０℃以下である、請求項１に記載の集電シート用樹脂フィルム。 The resin film for a current collector sheet according to claim 1, wherein the polyethylene resin layer has a melting point of 100°C or more and 120°C or less.
  3. 　前記ポリエチレン樹脂層の厚さが、前記基材層の厚さよりも厚い、請求項１または請求項２に記載の集電シート用樹脂フィルム。 The resin film for a current collector sheet according to claim 1 or 2, wherein the polyethylene resin layer is thicker than the base layer.
  4. 　前記ポリエチレン樹脂層の厚さが、４０μｍ以上１００μｍ以下である、請求項１または請求項２に記載の集電シート用樹脂フィルム。 The resin film for a current collector sheet according to claim 1 or 2, wherein the polyethylene resin layer has a thickness of 40 μm or more and 100 μm or less.
  5. 　前記基材層の厚さが、１２μｍ以上３８μｍ以下である、請求項１または請求項２に記載の集電シート用樹脂フィルム。 The resin film for a current collector sheet according to claim 1 or 2, wherein the base layer has a thickness of 12 μm or more and 38 μm or less.
  6. 　前記接着層の厚さが、０．１μｍ以上１０μｍ以下である、請求項１または請求項２に記載の集電シート用樹脂フィルム。 The resin film for a current collector sheet according to claim 1 or 2, wherein the adhesive layer has a thickness of 0.1 μm or more and 10 μm or less.
  7. 　前記基材層が、前記接着層とは反対の面に、表面処理部を有する、請求項１または請求項２に記載の集電シート用樹脂フィルム。 The resin film for a current collector sheet according to claim 1 or 2, wherein the base layer has a surface treated portion on a surface opposite to the adhesive layer.
  8. 　太陽電池の集電シートに用いられる集電シート用フィルムであって、
    　透明基材と、透明バリア層と、接着層と、封止層と、をこの順に有する、集電シート用フィルム。     A current collector sheet film used for a solar cell current collector sheet,
    A film for a current collector sheet, comprising a transparent base material, a transparent barrier layer, an adhesive layer, and a sealing layer in this order.
  9. 　前記透明バリア層と前記接着層との間に、保護層を有する、請求項８に記載の集電シート用フィルム。 The film for a current collector sheet according to claim 8, further comprising a protective layer between the transparent barrier layer and the adhesive layer.
  10. 　前記透明バリア層と前記接着層との間に、オーバーコート層を有する、請求項８または請求項９に記載の集電シート用フィルム。 The film for a current collector sheet according to claim 8 or 9, comprising an overcoat layer between the transparent barrier layer and the adhesive layer.
  11. 　水蒸気透過度が、１×１０－３ｇ／（ｍ２・ｄａｙ）以上１ｇ／（ｍ２・ｄａｙ）以下である、請求項８または請求項９に記載の集電シート用フィルム。 The film for a current collector sheet according to claim 8 or 9, having a water vapor permeability of 1×10 −3 g/(m 2 ·day) or more and 1 g/(m 2 ·day) or less.
  12. 　前記封止層が、ポリオレフィン樹脂を含有する、請求項８または請求項９に記載の集電シート用フィルム。 The film for a current collector sheet according to claim 8 or 9, wherein the sealing layer contains a polyolefin resin.
  13. 　前記ポリオレフィン樹脂が、ポリエチレン樹脂である、請求項１２に記載の集電シート用フィルム。 The film for a current collector sheet according to claim 12, wherein the polyolefin resin is a polyethylene resin.
  14. 　前記封止層が、前記接着層とは反対の面に、表面処理部を有する、請求項８または請求項９に記載の集電シート用フィルム。 The film for a current collector sheet according to claim 8 or 9, wherein the sealing layer has a surface treatment portion on a surface opposite to the adhesive layer.
  15. 　太陽電池に用いられる集電シートであって、
    　請求項１または請求項２に記載の集電シート用樹脂フィルムと、
    　前記集電シート用樹脂フィルムの前記ポリエチレン樹脂層の面側に配置されたワイヤと、
    　を有する、集電シート。     A current collector sheet used for solar cells,
    The resin film for a current collector sheet according to claim 1 or 2,
    a wire disposed on the surface side of the polyethylene resin layer of the resin film for current collector sheet;
    A current collecting sheet having.
  16. 　太陽電池に用いられる集電シートであって、
    　請求項８または請求項９に記載の集電シート用フィルムと、
    　前記集電シート用フィルムの前記封止層の面側に配置されたワイヤと、
    　を有する、集電シート。     A current collector sheet used for solar cells,
    The film for current collector sheet according to claim 8 or 9,
    a wire disposed on the surface side of the sealing layer of the current collector sheet film;
    A current collecting sheet having.
  17. 　請求項１５に記載の集電シートと、
    　前記集電シートの前記ポリエチレン樹脂層の面側に配置され、前記ワイヤと電気的に接続された太陽電池素子と、
    　を有する、集電シート付き太陽電池素子。     The current collector sheet according to claim 15,
    a solar cell element arranged on the surface side of the polyethylene resin layer of the current collector sheet and electrically connected to the wire;
    A solar cell element with a current collecting sheet.
  18. 　請求項１６に記載の集電シートと、
    　前記集電シートの前記封止層の面側に配置され、前記ワイヤと電気的に接続された太陽電池素子と、
    　を有する、集電シート付き太陽電池素子。     The current collector sheet according to claim 16,
    a solar cell element disposed on the side of the sealing layer of the current collector sheet and electrically connected to the wire;
    A solar cell element with a current collecting sheet.
  19. 　透明基板と、第１封止材と、請求項１７に記載の集電シート付き太陽電池素子と、第２封止材と、対向基板と、をこの順に有する、太陽電池。 A solar cell comprising, in this order, a transparent substrate, a first encapsulant, the solar cell element with a current collector sheet according to claim 17, a second encapsulant, and a counter substrate.
  20. 　透明基板と、第１封止材と、請求項１８に記載の集電シート付き太陽電池素子と、第２封止材と、裏面保護シートと、をこの順に有する、太陽電池。 A solar cell comprising, in this order, a transparent substrate, a first encapsulant, the solar cell element with a current collector sheet according to claim 18, a second encapsulant, and a back protection sheet.
  21. 　前記太陽電池は、複数の前記集電シート付き太陽電池素子を有する太陽電池モジュールである、請求項１９に記載の太陽電池。 The solar cell according to claim 19, wherein the solar cell is a solar cell module having a plurality of solar cell elements with the current collector sheet.
  22. 　前記太陽電池は、複数の前記集電シート付き太陽電池素子を有する太陽電池モジュールである、請求項２０に記載の太陽電池。 The solar cell according to claim 20, wherein the solar cell is a solar cell module having a plurality of solar cell elements with the current collector sheet.
  23. 　前記裏面保護シートが、前記第２封止材側から順に、易接着層と、バリアフィルムと、基材層とを有する、請求項２０に記載の太陽電池。 The solar cell according to claim 20, wherein the back protection sheet includes, in order from the second encapsulant side, an easily adhesive layer, a barrier film, and a base layer.
PCT/JP2023/020931 2022-06-06 2023-06-06 Resin film for current collector sheets, film for current collector sheets, current collector sheet, solar cell element with current collector sheet, and solar cell WO2023238844A1 (en)

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JP2022-091429 2022-06-06
JP2022091429A JP2023178632A (en) 2022-06-06 2022-06-06 Resin film for power collection sheet, power collection sheet, solar battery element with power collection sheet, and solar battery
JP2022-091430 2022-06-06
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JP2010232463A (en) * 2009-03-27 2010-10-14 Lintec Corp Solar cell module
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