WO2014042217A1

WO2014042217A1 - Solar cell protective sheet and flexible solar cell module

Info

Publication number: WO2014042217A1
Application number: PCT/JP2013/074717
Authority: WO
Inventors: 嘉謨郭; 平池　宏至; 飛鳥　政宏; 清巳上ノ町; 一成八木; 石居　正裕; 良隆国広
Original assignee: 積水化学工業株式会社
Priority date: 2012-09-13
Filing date: 2013-09-12
Publication date: 2014-03-20
Also published as: JPWO2014042217A1

Abstract

The purpose of the present invention is to provide a solar cell protective sheet having high adhesiveness between a protective layer and an adhesive sealing layer and excellent durability, and a flexible solar cell module in which the solar cell elements are protected by said solar cell protective sheet. This solar cell protective sheet is a laminate of a protective layer comprising a fluorine-based resin sheet, and an adhesive sealing layer, wherein the protective layer has a surface layer with 0.2mol% or more nitrogen atoms on the surface contacting the adhesive sealing layer, and the adhesive sealing layer contains a heat-adhesive resin having an acid group or an acid anhydride group.

Description

Solar cell protective sheet and flexible solar cell module

The present invention relates to a highly durable solar cell protective sheet having high adhesion between a protective layer and an adhesive sealing layer, and a flexible solar cell module in which a solar cell element is protected by the solar cell protective sheet.

As a solar cell, a rigid solar cell module based on glass and a flexible solar cell module based on a polyimide or polyester heat-resistant polymer material or a stainless thin film are known. In recent years, flexible solar cell modules have been attracting attention because of their ease of transportation and construction due to reduction in thickness and weight, and resistance to impact.

Such a flexible solar cell module is a flexible solar cell element in which a photoelectric conversion layer made of a silicon semiconductor or a compound semiconductor having a function of generating a current when irradiated with light is laminated in a thin film on a flexible substrate. The upper and lower surfaces are sealed with an adhesive sealing layer, and a protective layer is provided as the outermost layer.

As the adhesive sealing layer for sealing the solar cell element, it is a mainstream to use an ethylene-vinyl acetate (EVA) resin (for example, Patent Document 1). In addition, when EVA resin is used, there is a problem that the production time becomes long or an acid is generated due to the cross-linking process. Therefore, non-EVA resin such as silane-modified olefin resin is also studied. (For example, Patent Document 2).

A thermoplastic material has often been used for the protective layer because it has high impact resistance and is light. Among them, poly (vinylidene fluoride) (PVDF) is superior in that it has excellent weather resistance, radiation resistance, chemical resistance, is relatively inert, and has a very low surface energy, so that it is difficult for contaminants to adhere to it. Have been used (for example, Patent Document 3).

However, in the conventional flexible solar cell module, the adhesion between the adhesive sealing layer and the protective layer is insufficient, and the protective layer may peel off from the adhesive sealing layer when left in the environment for a long time. There was a problem in terms of durability.
On the other hand, an attempt is made to improve the adhesion between layers by providing an adhesive layer made of an acrylic resin or a mixture of an acrylic resin and a fluororesin between the adhesive sealing layer and the protective layer. . However, when such an adhesive layer is used, there is a problem that the weather resistance and heat resistance are remarkably lowered. In addition, when the adhesive layer is provided, wrinkles and curls occur in the process of continuously sealing solar cell elements by the roll-to-roll method, which has recently been attracting attention as a method excellent in mass production, particularly during the manufacturing process. There was also a problem that it became easier.

JP 7-297439 A JP 2004-214641 A International Publication No. 2008/019229 Pamphlet

The present invention provides a highly durable solar cell protective sheet having high adhesion between a protective layer and an adhesive sealing layer, and a flexible solar cell module in which solar cell elements are protected by the solar cell protective sheet. For the purpose.

The present invention is a solar cell protective sheet in which a protective layer made of a fluororesin sheet and an adhesive sealing layer are laminated, wherein the protective layer has a nitrogen atom concentration of 0. 0 on the surface in contact with the adhesive sealing layer. It has a surface layer containing 2 mol% or more, and the adhesive sealing layer is a solar cell protective sheet containing a thermal adhesive resin having an acid group or an acid anhydride group.
The present invention is described in detail below.

The inventors of the present invention form a surface layer containing 0.2 mol% or more of nitrogen atoms on the surface of the protective layer made of a fluororesin sheet in contact with the adhesive sealing layer, and thermally bond the acid group or the acid anhydride group. It has been found that the adhesive strength between layers can be remarkably increased by combining with an adhesive sealing layer containing an adhesive resin. According to the present invention, the adhesiveness between the protective layer and the adhesive sealing layer can be improved without providing an adhesive layer as in the prior art, so there is no deterioration in weather resistance or heat resistance, and roll-to-roll method or the like. Therefore, even when the solar cell elements are continuously sealed, wrinkles and curls are hardly generated.

The solar cell protective sheet of the present invention has a structure in which a protective layer and an adhesive sealing layer are laminated. In FIG. 1, the longitudinal cross-section schematic diagram of an example of the solar cell protection sheet B which consists of the protective layer 1 and the adhesion sealing layer 2 is shown. In FIG. 1, a surface layer 12 containing 0.2 mol% or more of nitrogen atoms is formed on the surface of the protective layer 1 in contact with the adhesive sealing layer 2.
When the solar cell protection sheet of the present invention is used to protect the solar cell element, the protective layer is the outermost layer in the obtained flexible solar cell module, and prevents external impact or corrosion of the solar cell element. It has a role to prevent.

The protective layer is made of a fluorine resin sheet.
The fluororesin sheet is not particularly limited as long as it is excellent in transparency, heat resistance, and flame retardancy. Tetrafluoroethylene-ethylene copolymer (ETFE), ethylene chlorotrifluoroethylene resin (ECTFE), Polychlorotrifluoroethylene resin (PCTFE), polyvinylidene fluoride resin (PVDF), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (FAP), polyvinyl fluoride resin (PVF), tetrafluoroethylene-hexafluoropropylene At least one selected from the group consisting of a copolymer (FEP), a vinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), and a mixture of polyvinylidene fluoride and polymethyl methacrylate (PVDF / PMMA) of It is preferably made of Tsu Motokei resin.
Of these, the fluororesin is more preferably a polyvinylidene fluoride resin (PVDF), a tetrafluoroethylene-ethylene copolymer (ETFE), or a polyvinyl fluoride resin (PVF) in that it is superior in heat resistance and transparency.

The protective layer has a surface layer containing 0.2 mol% or more of nitrogen atoms on the surface in contact with the adhesive sealing layer. By having such a surface layer, the adhesive force with the adhesive sealing layer containing the heat-adhesive resin having an acid group or an acid anhydride group is remarkably increased, and the protective layer when left in the environment for a long time. Can be prevented from peeling off from the adhesive sealing layer.
This is because a functional group containing a nitrogen atom contained in the surface layer (for example, an amino group) reacts with an acid group or an acid anhydride group of the heat-adhesive resin to chemically bond or electrostatically bond. It is thought that it is to do.

The lower limit of the nitrogen atom content in the surface layer is 0.2 mol%. If it is less than 0.2 mol%, the effect of improving the adhesion between the protective layer and the adhesive sealing layer cannot be obtained. The minimum with preferable content of the nitrogen atom in the surface layer of the said protective layer is 0.5 mol%, and a more preferable minimum is 1.0 mol%. The upper limit of the content of nitrogen atoms in the surface layer of the protective layer is not particularly limited, but technically about 20 mol% is considered to be a substantial upper limit.
In addition, in this specification, content of the nitrogen atom in a surface layer means the ratio of content of the nitrogen atom with respect to content of all the atoms contained in the said surface layer. Here, the content of each atom contained in the surface layer can be measured by, for example, X-ray photoelectron spectroscopy (XPS) or Auger electron spectroscopy (AES).

A preferable lower limit of the thickness of the surface layer is 0.05 nm. If the thickness of the surface layer is less than 0.05 nm, the effect of improving the adhesion between the protective layer and the adhesive sealing layer may not be obtained. A more preferable lower limit of the thickness of the surface layer is 0.1 nm. The upper limit of the thickness of the surface layer is not particularly limited, but technically about 10 nm is considered to be a substantial upper limit.
Note that the thickness of the surface layer is measured from a cross-sectional plot of the surface layer specific element by etching the surface layer using, for example, X-ray photoelectron spectroscopy (XPS) or Auger electron spectroscopy (AES). Can do.

Examples of the method for forming the surface layer on the surface of the protective layer in contact with the adhesive sealing layer include a method in which the surface of the protective layer is subjected to plasma treatment and a method in which corona discharge treatment is performed in a nitrogen atmosphere. When the protective layer is subjected to these surface treatments to form a surface layer, the adhesive strength with the adhesive sealing layer containing an acid group or an acid anhydride group is remarkably increased, and when left in the environment for a long time. It is possible to prevent the protective layer from being peeled off from the adhesive sealing layer. Among them, the method of performing plasma treatment is preferable because the generation of wrinkles is reduced and the adhesive strength after high temperature and high humidity conditions can be maintained high.

The plasma treatment to the protective layer can be performed by a conventionally known method. Specific examples include nitrogen gas plasma, nitrogen / methane mixed gas plasma, nitrogen / carbon dioxide mixed gas plasma, and nitrogen / argon mixed gas plasma.
In order to set the content of nitrogen atoms in the surface layer formed in the protective layer to 0.2 mol% or more, for example, nitrogen gas plasma under conditions of a processing speed of 25 m / min or less and a processing intensity of 0.8 kW or more. It is preferable to process.

The corona discharge treatment to the protective layer can be performed by a conventionally known method. Specific examples include nitrogen gas corona, nitrogen / hydrogen mixed gas corona, nitrogen / amine mixed gas corona, and nitrogen / methane mixed gas corona.
In order to set the content of nitrogen atoms in the surface layer formed in the protective layer to 0.2 mol% or more, for example, it is preferable to perform nitrogen gas corona discharge treatment under the condition of a treatment amount of 20 W / m ² or more. .

The protective layer preferably has an embossed shape on the surface in contact with the adhesive sealing layer. When the protective layer has an embossed shape, the adhesive force between the protective layer and the adhesive sealing layer can be further increased.
The emboss shape on the surface of the protective layer may be a regular uneven shape or a random uneven shape.

The protective layer has an embossed shape on the surface opposite to the surface in contact with the adhesive sealing layer, that is, the surface that seals the solar cell element and becomes the outermost layer of the flexible solar cell module. It is preferable. When the outermost layer has an embossed shape, it is possible to reduce the reflection loss of sunlight, prevent glare, and improve the appearance.

The embossed shape is a method of performing embossing at the same time when the molten resin is cooled by using an embossed roll as a cooling roll when the fluororesin sheet constituting the protective layer is extruded by a melt extrusion method. Or the like.
When the protective layer has an embossed shape on the surface, the embossing may be performed after the plasma treatment or the corona discharge treatment first, but the embossed shape is determined by a method using an embossing roll in the melt extrusion method. A method of performing plasma treatment or corona discharge treatment on the embossed surface of the applied fluororesin sheet by the above method is preferable.

The preferable lower limit of the thickness of the protective layer is 10 μm, and the preferable upper limit is 100 μm. If the thickness of the protective layer is less than 10 μm, insulation may not be ensured or flame retardancy may be impaired. If the thickness of the protective layer exceeds 100 μm, the weight of the flexible solar cell module may be increased, which is economically disadvantageous. The minimum with more preferable thickness of the said protective layer is 15 micrometers, and a more preferable upper limit is 80 micrometers.

The solar cell protective sheet of the present invention has an adhesive sealing layer. The said adhesive sealing layer has a role which seals a solar cell element.
The adhesive sealing layer contains a heat-adhesive resin having an acid group or an acid anhydride group. A high interlayer adhesion can be achieved by combining such an adhesive sealing layer with a protective layer having a surface layer containing 0.2 mol% or more of the nitrogen atoms.

Examples of the acid group include a carboxyl group, an unsaturated carboxylic acid group, a hydroxy acid group, an aromatic carboxylic acid group, and a dicarboxylic acid group.
Examples of the acid anhydride group include a maleic anhydride group, an acetic anhydride group, a propionic anhydride group, a succinic anhydride group, a phthalic anhydride group, and a benzoic anhydride group.

Examples of the heat-adhesive resin having an acid group or an acid anhydride group include an acid-modified polyolefin, an acid-modified ethylene-glycidyl methacrylate copolymer, an ionomer, and an ethylene-acrylic acid ester-anhydride group copolymer. It is done. These thermal adhesive resins having an acid group or an acid anhydride group may be used alone or in combination of two or more.

The acid-modified polyolefin can prevent the generation of wrinkles and curls when a solar cell element is sealed using the solar cell protective sheet of the present invention to produce a flexible solar cell module, and the adhesion to the solar cell surface is improved. From the viewpoint of superiority, it is preferably a maleic anhydride-modified polyolefin.
The maleic anhydride-modified polyolefin is a resin in which an α-olefin-ethylene copolymer having an α-olefin content of 1 to 25% by weight is graft-modified with maleic anhydride, and the total content of maleic anhydride The amount is preferably 0.1 to 3% by weight.

The ionomer is preferably one obtained by neutralizing part or all of the unsaturated carboxylic acid group of the ethylene-unsaturated carboxylic acid copolymer with a metal ion.
Examples of the ethylene-unsaturated carboxylic acid copolymer include a copolymer comprising at least a copolymer component of ethylene and an unsaturated carboxylic acid.
The ionomer can be produced by a known method.

Examples of the unsaturated carboxylic acid include acrylic acid, methacrylic acid, maleic acid, phthalic acid, citraconic acid, itaconic acid, and the like, among which acrylic acid and methacrylic acid are preferable.
As said metal ion, a sodium ion and a zinc ion are preferable.
The minimum with preferable content of the said unsaturated carboxylic acid component is 15 weight%, and a preferable upper limit is 25 weight%.

The ethylene-unsaturated carboxylic acid copolymer may further contain a (meth) acrylic acid ester component as a third component.
The (meth) acrylic acid ester is at least one selected from the group consisting of methyl (meth) acrylate, ethyl (meth) acrylate and butyl (meth) acrylate from the viewpoint of cost and polymerizability. Is preferred. Among these, from the viewpoint of the melting point, an acrylate ester is preferable, and specifically, n-butyl acrylate, isobutyl acrylate, and ethyl acrylate are more preferable.
When the ethylene-unsaturated carboxylic acid copolymer contains the (meth) acrylic acid ester component, the content of the (meth) acrylic acid ester component is preferably 25% by weight or less. If the content of the (meth) acrylic acid ester component exceeds 25% by weight, the melting point may be too low. The upper limit with more preferable content of the said (meth) acrylic acid ester component is 20 weight%.

The ethylene- (meth) acrylic acid copolymer is preferably an ethylene-acrylic acid ester-maleic anhydride terpolymer.
The ethylene-acrylic acid ester-maleic anhydride terpolymer is a copolymer composed of at least three components of ethylene, acrylic acid ester and maleic anhydride.
The acrylic ester is preferably at least one selected from the group consisting of methyl acrylate, ethyl acrylate, and butyl acrylate from the viewpoint of cost and polymerizability.
The ethylene- (meth) acrylic acid copolymer has an ethylene component content of 71 to 93% by weight, an acrylic ester component content of 5 to 28% by weight, and a maleic anhydride component content. Is preferably 0.1 to 4% by weight.

The ethylene- (meth) acrylic acid copolymer is preferably an ethylene-glycidyl methacrylate copolymer.
The ethylene-glycidyl methacrylate copolymer is a copolymer composed of at least two components of ethylene and glycidyl methacrylate.
The content of the glycidyl methacrylate component in the ethylene-glycidyl methacrylate copolymer is preferably 7% by weight and preferably 9% by weight from the viewpoint of the melting point.
The ethylene-glycidyl methacrylate copolymer can be produced using a conventionally known polymerization method.

The ethylene-glycidyl methacrylate copolymer may further contain components derived from other monomers in addition to the ethylene component and the glycidyl methacrylate component.
The other monomer is not particularly limited as long as it is a monomer copolymerizable with ethylene and glycidyl methacrylate as long as the physical properties necessary for the present invention are not impaired. Of these, (meth) acrylate is preferred from the viewpoint of melting point, polymerizability, and cost.
The (meth) acrylate is preferably an acrylate, and methyl acrylate, ethyl acrylate or butyl acrylate is particularly preferable.
When the ethylene-glycidyl methacrylate copolymer contains the (meth) acrylate component, the preferable upper limit of the content of the (meth) acrylate component is 15% by weight, and the more preferable upper limit is 10% by weight. The lower limit is not particularly limited as long as the copolymer resin can be obtained.

The adhesive sealing layer preferably further contains a silane compound having a glycidyl group. By containing such a silane compound having a glycidyl group, the adhesive force between the protective layer and the adhesive sealing layer can be further improved. Moreover, since almost no foreign substances such as gel are generated when the solar cell protective sheet is manufactured, it can be manufactured continuously. Moreover, when a solar cell element is continuously sealed by a roll-to-roll method or the like, the resin hardly protrudes from the end portion of the protective layer of the obtained flexible solar cell module. Furthermore, the adhesive force between the adhesive sealing layer and the surface of the solar cell element can also be improved.

Examples of the silane compound having a glycidyl group include 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltrimethoxysilane, and 3-glycidoxypropyltriethoxy. Silane, 3-glycidoxypropyltripropoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltriethoxysilane, 2- (3,4-epoxy (Cyclohexyl) ethyltripropoxysilane and the like. Among them, 3-glycidoxypropyltrimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3- Glycidoxypropylmethyldiethoxysilane is preferred.

Commercially available silane compounds having a glycidyl group are Z-6040 (3-glycidoxypropyltrimethoxysilane), Z-6043 (2- (3,4-epoxycyclohexyl) ethyltril) manufactured by Toray Dow Corning. Methoxysilane), KBE-403 (3-glycidoxypropyltriethoxysilane), KBM-402 (3-glycidoxypropylmethyldimethoxysilane), KBE-402 (3-glycidoxypropyl) manufactured by Shin-Etsu Silicone Methyldiethoxysilane) and the like.

The content of the silane compound having a glycidyl group in the adhesive sealing layer is 0.05 to 5 parts by weight with respect to 100 parts by weight of the thermoadhesive resin having an acid group or an acid anhydride group. preferable. When the content of the silane compound is out of the above range, the adhesive force between the protective layer and the adhesive sealing layer and the adhesive force between the adhesive sealing layer and the solar cell element may be reduced. The content of the silane compound is more preferably 0.07 parts by weight with respect to 100 parts by weight of the thermoadhesive resin having the acid group or acid anhydride group, and the upper limit is 1.5 parts by weight. It is more preferable that

The said adhesive sealing layer may further contain the other additive in the range which does not impair the physical property. Examples of the other additives include, for example, an ultraviolet stabilizer, an antioxidant, a light resistance stabilizer, a plasticizer, a filler, a colorant, a pigment, an antistatic agent, a surfactant, a toning liquid, and a refractive index matching additive. Agents and dispersion aids.

The minimum with the preferable thickness of the said adhesive sealing layer is 80 micrometers, and a preferable upper limit is 700 micrometers. If the thickness of the adhesive sealing layer is less than 80 μm, the insulating property of the flexible solar cell module may not be maintained. If it exceeds 700 μm, the flame resistance of the flexible solar cell module may be adversely affected, or the flexible solar cell The module may become heavy. The minimum with more preferable thickness of the said adhesive sealing layer is 150 micrometers, and a more preferable upper limit is 400 micrometers.

The method for forming the adhesive sealing layer includes, for example, a predetermined weight ratio of a silane compound having a glycidyl group and an additive added as necessary to the thermal adhesive resin having an acid group or an acid anhydride group. And a method of forming an adhesive sealing layer by feeding into an extruder and melting and kneading, and extruding into a sheet form from the extruder.
As the extruder, a single screw extruder or a twin screw extruder may be used.

The solar cell protective sheet of the present invention is obtained by laminating the protective layer and the adhesive sealing layer.
As the lamination method, for example, a conventionally known method such as a vacuum laminating method, a roll laminating method, or an extrusion laminating method can be used.

The solar cell protective sheet of the present invention is for manufacturing a flexible solar cell module by sealing solar cell elements.
The flexible solar cell module in which the solar cell protective sheet of the present invention and the solar cell element in which the photoelectric conversion layer is disposed on the flexible base material are laminated and integrated are also one aspect of the present invention.

The solar cell element is generally composed of a photoelectric conversion layer in which electrons are generated by receiving light, an electrode layer for taking out the generated electrons, and a flexible substrate.
In FIG. 3, the longitudinal cross-sectional schematic diagram of an example of the solar cell element C by which the photoelectric converting layer 3 is arrange | positioned on the flexible base material 4 is shown. Note that the electrode layer is omitted here because various arrangements are possible.

The flexible substrate is not particularly limited as long as it is flexible and can be used for a flexible solar cell element. For example, heat-resistant resin such as polyimide, polyetheretherketone, polyethersulfone, etc. The base material which consists of can be mentioned.
The preferable lower limit of the thickness of the flexible substrate is 10 μm, and the preferable upper limit is 80 μm.

Examples of the photoelectric conversion layer include crystal semiconductors such as single crystal silicon, single crystal germanium, polycrystalline silicon, and microcrystalline silicon, amorphous semiconductors such as amorphous silicon, GaAs, InP, AlGaAs, Cds, CdTe, and Cu _2. Examples thereof include compounds formed from compound semiconductors such as S, CuInSe ₂ and CuInS ₂ , and organic semiconductors such as phthalocyanine and polyacetylene.
The photoelectric conversion layer may be a single layer or a multilayer.
The minimum with the preferable thickness of the said photoelectric converting layer is 0.5 micrometer, and a preferable upper limit is 10 micrometers.

The electrode layer is a layer made of an electrode material.
The electrode layer may be on the photoelectric conversion layer, between the photoelectric conversion layer and the flexible base, or on the surface of the flexible base, as necessary.
Further, the solar cell element may have a plurality of the electrode layers.
Since the electrode layer on the light receiving surface side (surface) needs to be transparent, the electrode material is preferably a general transparent electrode material such as a metal oxide. Although it does not specifically limit as said transparent electrode material, ITO or ZnO etc. are used suitably.
When the transparent electrode is not used, the bus electrode and the finger electrode attached thereto may be patterned with a metal such as silver.
The electrode layer on the back side (back side) does not need to be transparent and may be made of a general electrode material, but silver is preferably used as the electrode material.

It does not specifically limit as a method of manufacturing the said solar cell element, For example, it can manufacture by well-known methods, such as arrange | positioning the said photoelectric converting layer and an electrode layer on the said flexible base material.
The solar cell element may have a long shape wound in a roll shape or a rectangular sheet shape.

As shown in FIG. 2, the flexible solar cell module of the present invention has an adhesive sealing layer 2 and a protective layer 1 on the side of the photoelectric conversion layer 3 of the solar cell element C. The adhesive sealing layer and the protective layer may also be provided on the side surface of the flexible substrate. By having the adhesive sealing layer and the protective layer on the side surface of the flexible base material of the solar cell element, the solar cell module is better sealed and can be stably generated over a long period of time. be able to.

The longitudinal cross-sectional schematic diagram of an example of the flexible solar cell module of this invention in the case of having the said adhesion sealing layer and the said protective layer in the photoelectric conversion layer side surface and flexible base material side surface of the said solar cell element is shown in FIG.
FIG. 4 is a schematic longitudinal sectional view of a flexible solar cell module F of the present invention comprising a protective layer 1, an adhesive sealing layer 2, a photoelectric conversion layer 3, a flexible substrate 4, an adhesive sealing layer 2 and a protective layer 1 in this order. Indicates.

As a method for producing the flexible solar cell module of the present invention, the solar cell protective sheet comprising the adhesive sealing layer and the protective layer is formed on at least the light receiving surface of the solar cell element by using a pair of heat rolls. A method of constricting and thermocompression bonding can be mentioned.
The light receiving surface of the solar cell element is a surface that can receive light and is a surface on which the photoelectric conversion layer of the solar cell element is disposed.
In the method for manufacturing the flexible solar cell module, the solar cell element and the solar cell element are arranged in a state where the surface on which the photoelectric conversion layer of the solar cell element is disposed and the side surface of the adhesive sealing layer of the solar cell protection sheet are opposed to each other. A method of laminating solar cell protective sheets, constricting them using a pair of heat rolls, and thermocompression bonding is preferable.

The preferable lower limit of the temperature of the heat roll when constricting using the pair of heat rolls is 70 ° C., and the preferable upper limit is 160 ° C. If the temperature of the heat roll is less than 70 ° C., adhesion failure may occur. If the temperature of the heat roll exceeds 160 ° C., wrinkles are likely to occur during thermocompression bonding. A more preferable lower limit of the temperature of the heat roll is 80 ° C., and a more preferable upper limit is 110 ° C.

A preferable lower limit of the rotation speed of the heat roll is 0.1 m / min, and a preferable upper limit is 10 m / min. If the rotational speed of the heat roll is less than 0.1 m / min, wrinkles may easily occur after thermocompression bonding. When the rotation speed of the heat roll exceeds 10 m / min, there is a possibility that adhesion failure may occur. A more preferable lower limit of the rotation speed of the heat roll is 0.3 m / min, and a more preferable upper limit is 5 m / min.

An example of the method for producing the flexible solar cell module of the present invention will be specifically described with reference to FIG.
As shown in FIG. 5, first, a long solar cell protective sheet B composed of the protective layer and the adhesive sealing layer and wound in a roll shape, and a solar cell element C are prepared. And the roll of the solar cell protection sheet B and the solar cell element C is unwound, and the light receiving surface of the photoelectric conversion layer of the solar cell element C and the adhesive sealing layer surface of the solar cell protection sheet B are arranged to face each other. Both are laminated to obtain a laminated sheet D.
Next, the laminated sheet D is supplied between a pair of rolls E and E heated to a predetermined temperature, and the laminated sheet D is heated and thermocompression bonded while pressing in the thickness direction, so that the solar cell element C and the solar cell. The protective sheet B is bonded and integrated. Thereby, a photoelectric converting layer is sealed by the adhesive sealing layer, and the flexible solar cell module A can be obtained.

Moreover, as a method of sealing the side surface of the flexible substrate, for example, in the same manner as described above, the solar cell protective sheet of the present invention is applied to the side surface of the flexible substrate of the solar cell, and the adhesive sealing layer is a flexible substrate. And a method of thermocompression bonding by narrowing them using a pair of heat rolls.
The step of thermocompression bonding the solar cell protective sheet to the flexible substrate side surface of the solar cell may be performed on the light receiving surface of the solar cell element described above before the step of thermocompression bonding the solar cell protective sheet, It may be done at the same time or later.

Using the solar cell protective sheet of the present invention, for example, an example of a method for producing the flexible solar cell module of the present invention by simultaneously sealing the photoelectric conversion layer side surface and the flexible substrate side surface of the solar cell element, This will be described with reference to FIG.
Specifically, while preparing a long solar cell element C wound in a roll shape, two long solar cell protective sheets wound in a roll shape are prepared. And as shown in FIG. 6, while unwinding the elongate solar cell protection sheets B and B, respectively, unwind the elongate solar cell element C, and the adhesive sealing layer of two solar cell protection sheets is In a state of facing each other, the solar cell protective sheets B and B are overlapped with each other through the solar cell element C to obtain a laminated sheet D. And by supplying the laminated sheet D between a pair of rolls E, E heated to a predetermined temperature, and heating the laminated sheet D while pressing the laminated sheet D in the thickness direction, the solar cell protective sheets B, B are brought together. The solar cell element C is sealed with the solar cell protective sheets B and B, and the flexible solar cell module F is continuously manufactured.
In the production of the flexible solar cell module, the solar cell protective sheets B and B are overlapped with each other via the solar cell element C to form the laminated sheet D, and at the same time, the laminated sheet D is heated while being pressed in the thickness direction. May be.

Moreover, an example of the manufacturing point of the flexible solar cell module of this invention at the time of using a rectangular sheet-like thing as the solar cell element C is shown in FIG.
Specifically, instead of the long solar cell element C wound in a roll shape, a rectangular sheet-like solar cell element C having a predetermined size is prepared. And as shown in FIG. 7, the solar cell protection sheet which unwinded the elongate solar cell protection sheet B and B currently wound by roll shape, and made each adhesive sealing layer face each other. A solar cell element C is supplied between B and B at predetermined time intervals, and the solar cell protective sheets B and B are overlapped with each other via the solar cell element C to obtain a laminated sheet D. And by supplying the laminated sheet D between a pair of rolls E, E heated to a predetermined temperature, and heating the laminated sheet D while pressing the laminated sheet D in the thickness direction, the solar cell protective sheets B, B are brought together. The solar cell element C is sealed with the solar cell protective sheets B and B, and the flexible solar cell module F is continuously manufactured.
In the production of the flexible solar cell module, the laminated sheet D may be heated while being pressed in the thickness direction simultaneously with the formation of the laminated sheet D.
The flexible solar cell module of the present invention can be suitably manufactured by applying such a roll-to-roll method.

As a method for producing the flexible solar cell module of the present invention, for example, the solar cell protective sheet and the solar cell element of the present invention cut into a desired shape are prepared, and the adhesive sealing layer of the solar cell protective sheet; The solar cell protective sheet and the solar cell element are laminated in a state where the photoelectric conversion layer side surface or both surfaces of the solar cell element are opposed to each other, and the obtained laminate is stationary under reduced pressure. The method may be such that the solar cell element is sealed with the solar cell protective sheet by heating while applying a pressing force in the thickness direction.
The step of heating the laminate while applying a pressing force in the thickness direction under reduced pressure can be performed using a conventionally known apparatus such as a vacuum laminator.

ADVANTAGE OF THE INVENTION According to this invention, the flexible solar cell module by which the solar cell element was protected by the solar cell protective sheet excellent in durability with the high adhesiveness of a protective layer and an adhesive sealing layer, and this solar cell protective sheet. Can be provided.

It is the longitudinal cross-sectional schematic diagram which showed an example of the solar cell protection sheet. It is the longitudinal cross-sectional schematic diagram which showed an example of the flexible solar cell module of this invention. It is the longitudinal cross-sectional schematic diagram which showed an example of the solar cell element. It is the longitudinal cross-sectional schematic diagram which showed an example of the flexible solar cell module of this invention. It is the schematic diagram which showed an example of the manufacturing point of the flexible solar cell module of this invention. It is the schematic diagram which showed an example of the manufacturing point of the flexible solar cell module of this invention. It is the schematic diagram which showed an example of the manufacturing point of the flexible solar cell module of this invention.

Hereinafter, embodiments of the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples.

(Example 1)
(1) Preparation of PVDF sheet having surface layer Polyvinylidene fluoride (PVDF, manufactured by Arkema Corp., Kyner 720) is used as a fluororesin using a single screw extruder at 250 ° C., 180 rotations / minute, extrusion rate of 12 kg / hour. After melt-kneading under the above conditions, melt extrusion was performed, and an embossing roll was used as a cooling roll, thereby obtaining a PVDF sheet having a thickness of 50 μm having an embossed shape on one surface.
Using a plasma processing apparatus (AP / T04-R1540 apparatus and product lineup made by Sekisui Chemical Co., Ltd.) on the surface of the obtained PVDF sheet having an embossed shape, 1 head, sheet processing speed of 5 m / min, processing strength of 1 A nitrogen gas plasma treatment was performed under a condition of 3 kW to obtain a PVDF sheet having a surface layer.
About the PVDF sheet which has the obtained surface layer, when nitrogen atom content of the surface layer was measured by X-ray photoelectron spectroscopy (XPS), it was 2.02 mol%.

(2) Production of solar cell protective sheet Modified olefin resin 100 obtained by graft-modifying a butene-ethylene copolymer having an ethylene component content of 75% by weight and a butene component content of 25% by weight with maleic anhydride A composition for an adhesive sealing layer comprising, by weight, 0.5 part by weight of 3-glycidoxypropyltrimethoxysilane (trade name “Z-6040”, manufactured by Dow Corning Toray) as a silane compound having a glycidyl group The product was supplied to an extruder and melt kneaded at 250 ° C. Then, the adhesive sealing layer composition is laminated while being extruded on the surface layer of the PVDF sheet having the surface layer obtained above to form an adhesive sealing layer, and contains a modified olefin resin and a silane compound. A solar cell protective sheet having a long and constant width was obtained by laminating and integrating an adhesive sealing layer having a thickness of 300 μm and a protective layer having a thickness of 50 μm.
The modified olefin resin used had a melt flow rate (MFR) of 3 g / 10 min and a maximum peak temperature (Tm) of an endothermic curve measured by differential scanning calorimetry of 80 ° C. The total content of maleic anhydride in the modified olefin resin was 0.3% by weight.

(3) Manufacture of flexible solar cell module Using the obtained solar cell protective sheet, a flexible solar cell module was produced in the following manner.

(3-1) Production of flexible solar cell module by roll-to-roll method First, a photoelectric conversion layer made of thin amorphous silicon is formed on a flexible base material made of a flexible polyimide film, and A solar cell element wound in a roll shape and a solar cell protection sheet in which the solar cell protection sheet obtained above was wound in a roll shape were prepared.
Next, as shown in FIG. 6, the solar cell element C and the solar cell protection sheet B are unwound, the solar cell protection sheet B is placed on the photoelectric conversion layer of the solar cell element C, and the adhesive sealing layer is the photoelectric conversion layer. Laminated sheets D were laminated so as to face the layers. Then, the laminated sheet D is supplied between a pair of rolls E and E heated to the temperatures shown in Table 1, and the laminated sheet D is heated while pressing the laminated sheet D in the thickness direction, and the solar cell protective sheet The photoelectric conversion layer was sealed by bonding and integrating B with the solar cell element C, and the flexible solar cell module A was continuously manufactured, and wound around a winding shaft (not shown).

(3-2) Manufacture of flexible solar cell module by vacuum laminating method First, a solar cell element in which a photoelectric conversion layer made of amorphous silicon in the form of a thin film is formed on a flexible base material made of a polyimide film having flexibility. The solar cell protective sheet obtained above was prepared by cutting it into a predetermined shape.
Next, the solar cell protective sheet and the solar cell element were laminated in a state where the adhesive sealing layer of the solar cell protective sheet and the photoelectric conversion layer side surface of the solar cell element were opposed to each other. The obtained laminate is heated using a vacuum laminator under a reduced pressure atmosphere of 1000 Pa or less while applying a pressing force in the thickness direction under the conditions shown in Table 1, and the solar cell element is sealed with a solar cell protective sheet. Stopped.

(Examples 2 to 4, 7 to 9, 13, 15 and Comparative Examples 1 to 4, 6)
In the preparation of PVDF sheet, the presence or absence of embossed shape, the plasma treatment conditions were changed as shown in Tables 1 to 4, and the composition of modified olefin resin and the presence or absence of silane compound in the production of solar cell protective sheet A solar cell protective sheet and a flexible solar cell module were obtained in the same manner as in Example 1 except that the values were changed as shown in Tables 1 to 4.

(Examples 5 and 14)
A vinylidene fluoride-hexafluoropropylene copolymer (trade name “Kyner Flex 2800” manufactured by Arkema Co., Ltd.) as a fluororesin is used at 250 ° C., 180 rotations / minute, and an extrusion rate of 12 kg / hour using a single screw extruder. After melt kneading under the conditions, melt extrusion was performed, and an embossing roll was used as a cooling roll to obtain a 50 μm thick PVDF-HFP copolymer sheet having an embossed shape on one surface.
The surface of the obtained PVDF-HFP copolymer sheet having an embossed shape is subjected to plasma surface treatment using a plasma treatment device (AP / T04-R1540 device and product lineup manufactured by Sekisui Chemical Co., Ltd.) A PVDF sheet was obtained. Except for changing the plasma treatment conditions as shown in Tables 1 and 2 or changing the composition of the modified olefin resin and the presence or absence of the silane compound in the production of the solar cell protective sheet as shown in Tables 1 and 2. A solar cell protective sheet and a flexible solar cell module were obtained in the same manner as in Example 1.

(Example 6)
Tetrafluoroethylene-ethylene copolymer (trade name “Neofluon ETFE”, manufactured by Daikin Industries, Ltd.) is used as a fluororesin under the conditions of 310 ° C., 180 rotations / minute, extrusion rate of 12 kg / hour using a single screw extruder. After melt kneading, melt extrusion was performed, and an embossing roll was used as a cooling roll to obtain an ETFE sheet having an embossed shape on one surface and a thickness of 50 μm. Using a plasma processing apparatus (AP / T04-R1540 apparatus and product lineup, manufactured by Sekisui Chemical Co., Ltd.) on the surface having an embossed shape of the obtained ETFE sheet, 1 head, sheet processing speed 10 m / min, processing strength 1 A nitrogen gas plasma treatment was performed under a condition of .3 kW to obtain an ETFE sheet having a surface layer.
A solar cell protective sheet and a flexible solar cell module were obtained in the same manner as in Example 1 except that the ETFE sheet having the obtained surface layer was used.

(Example 10, Comparative Example 7)
In the preparation of the PVDF sheet, the plasma treatment conditions were as shown in Tables 2 and 4.
A commercial product of ionomer resin (trade name: Himiran 1705, Zn ion type, manufactured by Mitsui DuPont Polychemical Co., Ltd.) was used in place of the modified olefin-based resin. A solar cell protective sheet and a flexible solar cell module were obtained in the same manner as in Example 1.

(Example 11, Comparative Example 8)
In the preparation of the PVDF sheet, the plasma treatment conditions were as shown in Tables 2 and 4.
Instead of the modified olefin-based resin, an ethylene-acrylic acid ester-maleic anhydride terpolymer containing a predetermined amount of components described in Tables 2 and 4 was used, as described in Tables 2 and 4. Except for the above, a solar cell protective sheet and a flexible solar cell module were obtained in the same manner as in Example 1.

(Example 12, Comparative Example 9)
In the preparation of the PVDF sheet, the plasma treatment conditions were as shown in Tables 2 and 4.
Instead of the modified olefin resin, a resin obtained by modifying an ethylene-glycidyl methacrylate copolymer containing a predetermined amount of ethylene component and glycidyl methacrylate component described in Tables 2 and 4 with maleic anhydride was used. Except as described, a solar cell protective sheet and a flexible solar cell module were obtained by the same method as in Example 1.

(Example 16)
(1) Preparation of PVDF sheet having surface layer Polyvinylidene fluoride (PVDF, manufactured by Arkema Corp., Kyner 720) is used as a fluororesin using a single screw extruder at 250 ° C., 180 rotations / minute, extrusion rate of 12 kg / hour. After melt-kneading under the above conditions, melt extrusion was performed, and an embossing roll was used as a cooling roll, thereby obtaining a PVDF sheet having a thickness of 50 μm having an embossed shape on one surface.
The surface having the embossed shape of the obtained PVDF sheet is subjected to a nitrogen gas corona discharge treatment using a corona discharge treatment device (manufactured by Kasuga Denki Co., Ltd., high frequency power supply device and treatment station) under conditions of a treatment amount of 20 W / m ^2. A PVDF sheet having a surface layer was obtained.
A solar cell protective sheet and a flexible solar cell module were obtained in the same manner as in Example 1 except that the obtained PVDF sheet having the surface layer was used.

(Examples 17 and 18, Comparative Example 5)
Except for changing the corona discharge treatment conditions as shown in Tables 2 and 3 in the preparation of the PVDF sheet, and changing the presence or absence of the silane compound as shown in Tables 2 and 3 in the production of the solar cell protective sheet. A solar cell protective sheet and a flexible solar cell module were obtained in the same manner as in Example 16.

(Evaluation)
About the obtained solar cell protective sheet, the delamination strength between the protective layer and the adhesive sealing layer was measured in the following manner, and the results are shown in Tables 1 to 4.

(1) Evaluation of initial delamination strength In the obtained flexible solar cell module, the peel strength when the protective layer and the adhesive sealing layer were peeled was measured according to JIS K6854.
In addition, when it was not able to peel with the force of 60 N / cm or more, material itself was destroyed.
The initial delamination strength between the protective layer and the adhesive sealing layer is generally required to be 10 N / cm or more, preferably 20 N / cm or more, and more preferably 30 N / cm or more.

(2) Evaluation of delamination strength after endurance at high temperature and high humidity The obtained flexible solar cell module is allowed to stand for 3000 hours in an environment of 85 ° C. and 85% relative humidity described in JIS C8991, and the protective layer and adhesive seal The peel strength when peeled from the stop layer was measured according to JIS K6854.
In addition, when it was not able to peel with the force of 60 N / cm or more, material itself was destroyed.
The delamination strength after high temperature and high humidity durability between the protective layer and the adhesive sealing layer is generally required to be 10 N / cm or more, preferably 20 N / cm or more, and more preferably 30 N / cm or more. Yes.

(3) High temperature and high humidity durability (power generation characteristics)
The obtained flexible solar cell module was left in an environment of 85 ° C. and a relative humidity of 85% described in JIC C8990, and the amount of change in the maximum output Pmax was measured using 1116N manufactured by Nissin Tor. In addition, about what peeling was confirmed in less than 1000 hours, it did not implement. The evaluation results shown in Tables 1 to 4 mean the following.
> 3000H: Maintaining 95% output after 3000 hours.
1500H: Maintains 95% output until 2000 hours.
1000H: 95% output maintained until 1000 hours (JIS-C8991 standard).
500H: 95% output maintained until 500 hours have passed.

A, F Flexible solar cell module B Solar cell protective sheet C Solar cell element D Laminated sheet E Roll 1 Protective layer 12 Surface layer 2 Adhesive sealing layer 3 Photoelectric conversion layer 4 Flexible base material

Claims

A solar cell protective sheet in which a protective layer made of a fluorine resin sheet and an adhesive sealing layer are laminated,
The protective layer has a surface layer containing 0.2 mol% or more of nitrogen atoms on the surface in contact with the adhesive sealing layer,
The said adhesive sealing layer contains the heat adhesive resin which has an acid group or an acid anhydride group, The solar cell protective sheet characterized by the above-mentioned.
The solar cell protective sheet according to claim 1, wherein the protective layer has been subjected to plasma treatment on a surface in contact with the adhesive sealing layer.
The heat-adhesive resin having an acid group or an acid anhydride group is composed of an acid-modified polyolefin, an acid-modified ethylene-glycidyl methacrylate copolymer, an ionomer, and an ethylene-acrylic acid ester-anhydride group copolymer. The solar cell protective sheet according to claim 1, wherein the solar cell protective sheet is at least one selected.
The solar cell protective sheet according to claim 1, wherein the adhesive sealing layer contains a silane compound having a glycidyl group.
The fluororesin sheet constituting the protective layer is composed of tetrafluoroethylene-ethylene copolymer, ethylene chlorotrifluoroethylene resin, polychlorotrifluoroethylene resin, polyvinylidene fluoride resin, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer Selected from the group consisting of a polymer, a polyvinyl fluoride resin, a tetrafluoroethylene-hexafluoropropylene copolymer, a vinylidene fluoride-hexafluoropropylene copolymer, and a mixture of polyvinylidene fluoride and polymethyl methacrylate The solar cell protective sheet according to claim 1, 2, 3, or 4, comprising at least one fluorine-based resin.
The solar cell protective sheet according to claim 1, 2, 3, 4 or 5, wherein the protective layer has an embossed shape on a surface in contact with the adhesive sealing layer.
The solar cell protective sheet according to claim 1, 2, 3, 4, 5 or 6, and a solar cell element in which a photoelectric conversion layer is arranged on a flexible base material is laminated and integrated. Battery module.