JP2012222147A - Flexible solar cell module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flexible solar cell module which is excellent in the adhesive between a protection layer and an adhesive sealing layer and enables highly efficient manufacturing.SOLUTION: A flexible solar cell module includes: a protection layer formed by a fluoropolymer containing an epoxy group containing compound; an adhesive sealing layer formed by a maleic anhydride modified olefin based resin; and solar cell elements.

Description

The present invention relates to a flexible solar cell module that is excellent in adhesion between a protective layer constituting a flexible solar cell module and an adhesive sealing layer for sealing solar cell elements, and can be manufactured with high efficiency and high yield. .

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 a method for producing a flexible solar cell module, a vacuum thermocompression bonding method using a laminator is generally used. However, there is a problem that wrinkles are likely to occur if the film is loosened during crimping.
In recent years, a roll-to-roll method has been studied as a method for producing a flexible solar cell module because it is excellent in mass production (see, for example, Patent Document 1).
The roll-to-roll method uses a roll in which a film-like solar cell protective sheet composed of an adhesive sealing layer and a protective layer is wound, and the solar cell protective sheet unwound from the roll is used with a pair of rolls. In this method, the solar cell element is thermocompression-bonded and sealed, thereby continuously manufacturing a flexible solar cell module.
According to such a roll-to-roll method, it can be expected to continuously manufacture flexible solar cell modules with extremely high efficiency.

For the protective layer of the flexible solar cell module, a thermoplastic material has often been used because it has high impact resistance and is light. Among them, fluoropolymers are poly (vinylidene fluoride) because they are excellent in weather resistance, radiation resistance, chemical resistance, are relatively inert, and have a very low surface energy, so that contaminants hardly adhere to them. ) (PVDF) or the like has been conventionally used for the protective layer (see, for example, Patent Document 2).
On the other hand, sealing base materials, such as EVA and a thermoplastic resin, have been used for the adhesive sealing layer for sealing a solar cell element.

However, the adhesive sealing layer made of these sealing base materials does not have sufficient adhesiveness with the protective layer made of a fluoropolymer. For this reason, in order to improve the adhesiveness, for example, a method of applying an adhesive composition of an acrylic polymer or a mixture of an acrylic polymer and a fluoropolymer between an adhesive sealing layer and a film made of a fluoropolymer, etc. Is known (see, for example, Patent Document 3).

However, a mixture such as an acrylic polymer has a problem that the weather resistance and heat resistance are remarkably lowered as compared with the case of a fluoropolymer alone. Further, when the acrylic polymer mixture is used as a protective material for the flexible solar cell module, there is a problem that wrinkles and curls are generated during the manufacturing process, particularly in the step of continuously sealing the solar cell element. .

JP 2000-294815 A International Publication No. 2008/019229 Pamphlet Special table 2008-5313329 gazette

An object of this invention is to provide the flexible solar cell module which is excellent in the adhesiveness of a protective layer and an adhesive sealing layer, and can be manufactured with high efficiency in view of the said present condition.

The present invention provides a flexible solar cell module comprising a protective layer made of a fluoropolymer containing an epoxy group-containing compound, an adhesive sealing layer made of a maleic anhydride-modified olefin resin, and a solar cell element. is there.
The present invention is described in detail below.

The present invention is a flexible solar cell module that is excellent in adhesiveness between the protective layer and the adhesive sealing layer and can be manufactured with high efficiency by comprising the protective layer and the adhesive sealing layer with specific components. It is what.
That is, the present inventors reduce transparency and weather resistance by combining a protective layer made of a fluoropolymer containing an epoxy group-containing compound and an adhesive sealing layer made of a maleic anhydride-modified olefin resin. The present invention has been found by improving the adhesion between the protective layer and the adhesive sealing layer, and by applying a production method such as a roll-to-roll method, which can be produced with high efficiency. It came to.

The flexible solar cell module of the present invention has a protective layer made of a fluoropolymer containing an epoxy group-containing compound, an adhesive sealing layer made of maleic anhydride-modified olefin resin, and a solar cell element.
In FIG. 1, the longitudinal cross-sectional schematic diagram of an example of the flexible solar cell module A of this invention which has the protective layer 1, the adhesive sealing layer 2, and the solar cell element C is shown.

The flexible solar cell module of the present invention has a protective layer made of a fluoropolymer containing an epoxy group-containing compound.
The said protective layer is a layer which can become an outermost layer in the flexible solar cell module of this invention. Since the protective layer is made of a fluoropolymer, it is excellent in weather resistance, stain resistance, and the like.

The fluoropolymer is at least one selected from compounds having a vinyl group capable of initiating polymerization in a chain, at least one fluorine atom directly bonded to the vinyl group, and a fluoroalkyl group or a fluoroalkoxy group. Any polymer containing the monomer of

Examples of the monomer include, for example, vinyl fluoride; vinylidene fluoride (VDF, formula CH ₂ = CF ₂ ); trifluoroethylene (VF ₃ ); chlorotrifluoroethylene (CTFE); 1,2-difluoroethylene; Perfluoro (alkyl vinyl ether) such as tetrafluoroethylene (TFE); hexafluoropropylene (HFP); perfluoro (methyl vinyl ether) (PMVE), perfluoro (ethyl vinyl ether) (PEVE) and perfluoro (propyl vinyl ether) (PPVE); 1,3-dioxole); perfluoro (2,2-dimethyl-1,3-dioxole) (PDD); formula CF ₂ = CFOCF ₂ CF (CF ₃ ) OCF ₂ CF ₂ X (where X is SO ₂ F , _CO 2 H, C _{2 OH,} CH ₂ OCN or compounds of _CH 2 _OPO 3 H); formula _CF 2 ₌ compound of _{CFOCF 2 CF 2 SO 2 F)} ; the formula _{F (CF 2) n CH 2} OCF = CF 2 ( wherein n is 1 2, 3, 4 or 5); a compound of formula R ¹ CH ₂ OCF═CF _2, wherein R ¹ is hydrogen or F (CF ₂ ) _z , z is 1, 2, 3 or 4; Compounds of formula R ³ OCF═CH ₂ (where R ³ is F (CF ₂ ) _z —, z is 1, 2, 3 or 4); perfluorobutylethylene (PFBE); 3,3,3-trifluoro Mention may be made of propene and 2-trifluoromethyl-3,3,3-trifluoro-1-propene.
The fluoropolymer may be a homopolymer or a copolymer, and may contain a non-fluoromonomer such as ethylene as a constituent component.

The fluoropolymer is preferably selected from the following:
1) A homopolymer of vinylidene fluoride (VDF) and a copolymer thereof, preferably comprising at least 50% by weight of VDF. The comonomer of the copolymer is selected from chlorotrifluoroethylene (CTFE), hexafluoropropylene (HFP), trifluoroethylene (VF ₃ ) and tetrafluoroethylene (TFE).
2) Homopolymers and copolymers of trifluoroethylene (VF ₃ ),
3) Combine residues of chlorotrifluoroethylene (CTFE), tetrafluoroethylene (TFE), hexafluoropropylene (HFP) and / or ethylene (which may further include VDF and / or VF ₃ if desired) Copolymers, especially terpolymers.
Especially, it is preferable that the said fluoropolymer is a homopolymer and / or copolymer of a poly (vinylidene fluoride) (PVDF).

The PVDF contains VDF, preferably 50% by weight or more, more preferably 75% by weight or more, and still more preferably 85% by weight or more. The comonomer contained in the PVDF is preferably HFP and / or CTFE.

The PVDF preferably has a viscosity in the range of 100 Pa · s to 2000 Pa · s. When the viscosity is within the above range, it is suitable for extrusion molding and injection molding when forming the protective layer.
The viscosity is more preferably in the range of 300 Pa · s to 1200 Pa · s.
The viscosity is a value measured at 230 ° C. using a capillary rheometer at a shear rate of 100 s −1.

A commercial product may be used as the PVDF. Examples of commercially available PVDF products that can be used in the present invention include, for example, Kynar (registered trademark) 710, 720, 740 (manufactured by Arkema); Kynarflex (registered trademark) 2802, 2800, 2850, 3120 ( Arkema).

The protective layer further contains an epoxy group-containing compound.
By containing the epoxy group-containing compound, it is possible to improve the adhesion between the protective layer and the adhesive sealing layer described later while maintaining transparency and weather resistance.
The epoxy group-containing compound is not particularly limited, and examples thereof include an epoxy silane compound, an epoxychlorohydrin-bisphenol A type epoxy resin, an epoxychlorohydrin-bisphenol F type epoxy resin, and a glycidyl ether of tetrabromobisphenol A. Flame retardant type epoxy resin, novolak type epoxy resin, hydrogenated bisphenol A type epoxy resin, glycidyl ether type epoxy resin of bisphenol A propylene oxide adduct, p-oxybenzoic acid glycidyl ether ester type epoxy resin, m-aminophenol type epoxy resin Resin, diaminodiphenylmethane epoxy resin, urethane-modified epoxy resin, various alicyclic epoxy resins, N, N-diglycidylaniline, N, N-diglycidyl-o-toluidine triglycidyl Isocyanurate, polyalkylene glycol diglycidyl ether, glycidyl ethers of polyhydric alcohols such as glycerin, hydantoin type epoxy resins, and epoxy compounds of unsaturated polymers such as petroleum resins. These may be used alone or in combination of two or more.
Of these, an epoxysilane compound is preferable.

The said epoxy silane compound is a silane compound which has an epoxy group, and should just have at least 1 epoxy groups, such as an aliphatic epoxy group and an alicyclic epoxy group, in a molecule | numerator.
The epoxy silane compound is preferably a silane compound represented by the following general formula (I).

(In the formula, R ¹ represents a 3-glycidoxypropyl group or 2- (3,4-epoxycyclohexyl) ethyl group, R ² represents an alkyl group having 1 to 3 carbon atoms, and R ³ Represents an alkyl group having 1 to 3 carbon atoms, and n is 0 or 1.)

R ¹ represents a 3-glycidoxypropyl group represented by the following formula (II) or a 2- (3,4-epoxycyclohexyl) ethyl group represented by the following formula (III).

R ² is not particularly limited as long as it is an alkyl group having 1 to 3 carbon atoms, and examples thereof include a methyl group, an ethyl group, and a propyl group. A methyl group and an ethyl group are preferable, and a methyl group is preferable. More preferred.

The R ³ is not particularly limited as long as it is an alkyl group having 1 to 3 carbon atoms, and examples thereof include a methyl group, an ethyl group, and a propyl group, and a methyl group is preferable.

Examples of the silane compound represented by the general formula (I) include 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxysilane, Sidoxypropyltriethoxysilane, 3-glycidoxypropyltripropoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltriethoxysilane, 2- ( 3,4-epoxycyclohexyl) ethyltripropoxysilane and the like.

In the general formula (I), n is preferably 0.
Particularly preferable examples of the epoxysilane compound include 3-glycidoxypropyltrimethoxysilane and 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane.

The content of the epoxy group-containing compound is preferably 0.001 to 3 parts by weight with respect to 100 parts by weight of the fluoropolymer. If it is less than 0.001 part by weight, the adhesion between the protective layer and the adhesive sealing layer may be insufficiently improved. If it exceeds 3 parts by weight, the adhesiveness may be lowered.
As for content of the said epoxy group containing compound, it is more preferable that a minimum is 0.05 weight part with respect to 100 weight part of fluoropolymers, and it is more preferable that an upper limit is 1 weight part.

The protective layer preferably has a thickness of 5 to 200 μm. When the protective layer is formed as a film or an extrusion layer, the thickness is preferably 15 to 80 μm. On the other hand, when formed by coating, the thickness is preferably 5 to 25 μm.

As a method of forming the protective layer, for example, the fluoropolymer, the epoxy group-containing compound, and an additive that is added as necessary are supplied to an extruder at a predetermined weight ratio and melted and kneaded. And a method of forming a protective layer by extruding into a sheet form from an extruder.

The flexible solar cell module of the present invention has an adhesive sealing layer.
The adhesive sealing layer is a layer for sealing the solar cell element. The adhesive sealing layer is preferably adjacent to the protective layer.

The said adhesive sealing layer consists of maleic anhydride modified olefin resin. By setting it as the adhesive sealing layer which consists of the said maleic anhydride modified olefin resin, it can be excellent in the adhesiveness of the said adhesive sealing layer and a protective layer. Moreover, a flexible solar cell module can be efficiently manufactured also in the method of manufacturing by sealing continuously, such as a roll-to-roll method.

Examples of the maleic anhydride-modified olefin resin include an olefin resin graft-modified with maleic anhydride, a copolymer of ethylene or propylene and acrylic acid or methacrylic acid, or a metal-crosslinked polyolefin resin.
Among them, the maleic anhydride-modified olefin resin is preferably an olefin resin graft-modified with maleic anhydride.

The olefin resin may be a homopolymer composed of a single monomer or a copolymer composed of two or more kinds of monomers.
Specific examples of the homopolymer include polyethylene, polypropylene, polybutene, and the like.
Specific examples of the copolymer include an ethylene-α olefin copolymer and a polypropylene-α olefin copolymer.
As the olefin resin, an α-olefin-ethylene copolymer, which is a copolymer of α-olefin and ethylene, is preferable from the viewpoint of heat fusion.

The α-olefin-ethylene copolymer is preferably a copolymer composed of an α-olefin and ethylene.
The α-olefin preferably has 3 to 10 carbon atoms, and more preferably 4 to 8 carbon atoms, in order to lower the melting point and improve flexibility by improving the amorphousness of the resin.
Specific examples of the α-olefin include propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, and the like. Butene and 1-octene are preferred.
That is, the α-olefin-ethylene copolymer is preferably a butene-ethylene copolymer or an octene-ethylene copolymer.

As a method of graft-modifying the olefin resin with maleic anhydride, a known method is used. For example, a composition containing the olefin resin, maleic anhydride and a radical polymerization initiator is supplied to an extruder. Melt-kneading and then melt-modifying method in which maleic anhydride is graft-polymerized to the olefin resin, or a solution is prepared by dissolving the olefin resin in a solvent, and maleic anhydride and radical polymerization initiator are added to the solution. And a solution modification method in which maleic anhydride is graft-polymerized to the olefin resin. Especially, the said melt modification method is preferable on production at the point which can be mixed on-machine.

The radical polymerization initiator used in the above graft modification method is not particularly limited as long as it is conventionally used for radical polymerization. For example, benzoyl peroxide, cumene hydroperoxide, diisopropyl peroxydicarbonate , Cumyl peroxyneodecanoate, cumyl peroxyoctoate, azobisisobutyronitrile and the like.

The maleic anhydride-modified olefin resin is 5% by weight of a butene component, an ethylene-propylene-butene copolymer, an amorphous ethylene-propylene copolymer, a propylene-α-olefin copolymer, if necessary. It is preferable to contain above.

The maleic anhydride-modified olefin resin preferably has a total maleic anhydride content of 0.005 to 3% by weight.
There exists a possibility that the adhesiveness with respect to the solar cell element of the said adhesive sealing layer may fall that the total content of the said maleic anhydride is less than 0.005 weight%. If the total maleic anhydride content exceeds 3% by weight, the maleic anhydride-modified olefin resin may be cross-linked and the adhesiveness of the adhesive sealing layer may be reduced or the extrusion moldability may be reduced. There is.
The total content of maleic anhydride is more preferably 0.05% by weight at the lower limit, further preferably 0.1% by weight, and more preferably 1.5% by weight. More preferably, it is 1.0% by weight.
In addition, the total content of the maleic anhydride is determined from the absorption intensity in the vicinity of 1790 cm ⁻¹ by preparing a test film using the maleic anhydride-modified olefin resin and measuring the infrared absorption spectrum of the test film. Can be calculated. Specifically, the total content of maleic anhydride in the maleic anhydride-modified olefin resin is determined using, for example, FT-IR (Fourier Transform Infrared Spectrometer Nicolet 6700 FT-IR). (Analytical Society of Japan, published by Asakura Shoten, 2008).

The maleic anhydride-modified olefin resin preferably has a maximum peak temperature (Tm) of an endothermic curve measured by differential scanning calorimetry of 80 to 125 ° C.
When the maximum peak temperature (Tm) of the endothermic curve is lower than 80 ° C., the heat resistance of the adhesive sealing layer may be lowered. When the maximum peak temperature (Tm) of the endothermic curve is higher than 125 ° C., the heating time of the adhesive sealing layer becomes long in the sealing step, and the productivity of the flexible solar cell module is reduced, or the solar cell. There is a possibility that the sealing of the element becomes insufficient.
The maximum peak temperature (Tm) of the endothermic curve is more preferably 83 to 110 ° C.
In addition, the maximum peak temperature (Tm) of the endothermic curve measured by the differential scanning calorimetry can be measured according to the measurement method defined in JIS K7121.

The maleic anhydride-modified olefin resin preferably has a melt flow rate (MFR) of 0.5 g / 10 min to 29 g / 10 min. If the melt flow rate is less than 0.5 g / 10 min, the extrusion moldability of the adhesive sealing layer may be lowered. If it exceeds 29 g / 10 minutes, the extrusion moldability of the adhesive sealing layer may be reduced, and the thickness accuracy of the adhesive sealing layer may be reduced.
The melt flow rate is more preferably 2 g / 10 min to 10 g / 10 min.
The melt flow rate of the maleic anhydride-modified olefin resin is a value measured at a load of 2.16 kg in accordance with ASTM D1238, which is a method for measuring the melt blow rate of a polyethylene resin.

The maleic anhydride-modified olefin resin preferably has a viscoelastic storage elastic modulus at 30 ° C. of 2 × 10 ⁸ Pa or less. When the viscoelastic storage elastic modulus at 30 ° C. exceeds 2 × 10 ⁸ Pa, the flexibility of the adhesive sealing layer is reduced and handling properties are reduced, or the solar cell element is sealed with the adhesive sealing layer. When manufacturing the solar cell module by stopping, the adhesive sealing layer may need to be heated rapidly. If the viscoelastic storage elastic modulus at 30 ° C. is too low, the adhesive sealing layer may exhibit adhesiveness at room temperature and the handling property of the adhesive sealing layer may be lowered. × 10 ⁷ Pa is preferable. The upper limit is more preferably 1.5 × 10 ⁸ Pa.

The maleic anhydride-modified olefin resin preferably has a viscoelastic storage elastic modulus at 100 ° C. of 5 × 10 ⁶ Pa or less. When the viscoelastic storage elastic modulus at 100 ° C. exceeds 5 × 10 ⁶ Pa, the adhesion of the adhesive sealing layer to the solar cell element may be reduced.
When the viscoelastic storage elastic modulus at 100 ° C. is too low, when the solar cell element is sealed by the adhesive sealing layer to produce a solar cell module, the adhesive sealing layer flows greatly due to the pressing force. And since the nonuniformity of the thickness of the said adhesive sealing layer may become large, it is preferable that a minimum is 1 * 10 < ⁴ > Pa. The upper limit is more preferably 4 × 10 ⁶ Pa.
The viscoelastic storage elastic modulus of the maleic anhydride-modified olefin resin refers to a value measured by a dynamic property test method based on JIS K6394.

The adhesive sealing layer preferably further contains an epoxy group-containing compound.
By containing the epoxy group-containing compound, the adhesion to the protective layer and the solar cell element can be further improved.
As said epoxy group containing compound, the thing similar to the epoxy group containing compound used in the protective layer mentioned above can be mentioned.
Of these, the epoxy group-containing compound is preferably an epoxysilane compound.

The said epoxysilane compound is a compound which has an epoxy group, and should just have at least 1 epoxy groups, such as an aliphatic epoxy group and an alicyclic epoxy group, in a molecule | numerator. The epoxy silane compound is preferably a silane compound represented by the following general formula (I).

(In the formula, R ¹ represents a 3-glycidoxypropyl group or 2- (3,4-epoxycyclohexyl) ethyl group, R ² represents an alkyl group having 1 to 3 carbon atoms, and R ³ Represents an alkyl group having 1 to 3 carbon atoms, and n is 0 or 1.)

R ¹ represents a 3-glycidoxypropyl group represented by the following formula (II) or a 2- (3,4-epoxycyclohexyl) ethyl group represented by the following formula (III).

R ² is not particularly limited as long as it is an alkyl group having 1 to 3 carbon atoms, and examples thereof include a methyl group, an ethyl group, and a propyl group. A methyl group and an ethyl group are preferable, and a methyl group is preferable. More preferred.

The R ³ is not particularly limited as long as it is an alkyl group having 1 to 3 carbon atoms, and examples thereof include a methyl group, an ethyl group, and a propyl group, and a methyl group is preferable.

Examples of the silane compound represented by the general formula (I) include 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxysilane, Sidoxypropyltriethoxysilane, 3-glycidoxypropyltripropoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltriethoxysilane, 2- ( 3,4-epoxycyclohexyl) ethyltripropoxysilane and the like.

In the general formula (I), n is preferably 0.
As the epoxy silane compound, 3-glycidoxypropyltrimethoxysilane and 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane are particularly preferable.

The content of the epoxy group-containing compound in the adhesive sealing layer is preferably 0.05 to 5 parts by weight with respect to 100 parts by weight of the maleic anhydride-modified olefin resin.
There exists a possibility that the adhesiveness of the said adhesive sealing layer may fall that content of the said epoxy group containing compound is outside the above-mentioned range.
The lower limit of the content of the epoxy group-containing compound is more preferably 0.1 parts by weight and the upper limit is 1.5 parts by weight with respect to 100 parts by weight of the maleic anhydride-modified olefin resin. More preferred.

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 UV stabilizers, plasticizers, fillers, colorants, pigments, antioxidants, antistatic agents, surfactants, toning liquids, refractive index matching additives, and dispersion aids. Agents and the like.

The adhesive sealing layer preferably has a thickness of 80 to 700 μm.
If the thickness 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 retardancy of the flexible solar cell module may be adversely affected, the weight of the flexible solar cell module may be increased, and it is economically disadvantageous.
The thickness of the adhesive sealing layer is more preferably 150 to 400 μm.

As a method for forming the adhesive sealing layer, for example, the maleic anhydride-modified olefin-based resin, the epoxy group-containing compound, and an additive that is added as necessary are extruded at a predetermined weight ratio. And a method of forming an adhesive sealing layer by extruding into a sheet from an extruder.

The protective layer and the adhesive sealing layer can be combined to form a solar cell protective sheet.
In FIG. 2, 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.
The solar cell protective sheet can be produced by stacking and integrating the protective layer and the adhesive sealing layer. The method for integrating the layers is not particularly limited. For example, a method of forming the protective layer on one surface of the adhesive sealing layer formed in advance by extrusion lamination, or the adhesive sealing layer and the protective layer And the like, and the like.
Especially, it is preferable that the said solar cell protective sheet is formed by coextrusion at the point which can form the favorable coupling | bonding between the said protective layer and the said adhesive sealing layer.
In the coextrusion step, the extrusion setting temperature is preferably 30 ° C. or more from the melting point of the fluoropolymer and the maleic anhydride-modified olefin resin and less than 30 ° C. from the decomposition temperature.

The solar cell protective sheet preferably has an embossed shape on the surface. The solar cell protective sheet preferably has an embossed shape on the surface (protective layer surface) on the light receiving surface side when applied to a flexible solar cell module.
By having the said emboss shape, the reflection loss of sunlight can be reduced, glare can be prevented, and an external appearance can be improved.
The embossed shape may be a regular uneven shape or a random uneven shape.
The embossed shape may be embossed before being bonded to the solar cell element, embossed after being bonded to the solar cell element, or simultaneously molded in the step of bonding to the solar cell element. May be.
Among them, it is preferable to form by embossing before bonding to the solar cell element because there is no unevenness of emboss transfer and a uniform emboss shape can be obtained.
In particular, the above-mentioned adhesive sealing layer and protective layer are simultaneously formed by a co-extrusion process, and an embossing shape is simultaneously applied when cooling the molten resin using an embossing roll as a cooling roll. Since a uniform emboss shape can be maintained without deforming the emboss shape in the step of bonding to the element, it is more preferable.

The flexible solar cell module of the present invention has a solar cell element.
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 flexible substrate preferably has a thickness of 10 to 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 thickness of the photoelectric conversion layer is preferably 0.5 to 10 μm.

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.

The method for producing the solar cell element is not particularly limited as long as it is a known method. For example, it may be formed by a known method in which the photoelectric conversion layer or the electrode layer is disposed on the flexible substrate.
The solar cell element may have a long shape wound in a roll shape or a rectangular sheet shape.

As shown in FIG. 1, 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.

It is preferable that the temperature of the said heat roll at the time of constricting using said pair of heat roll is 70-160 degreeC. If it is less than 70 ° C., adhesion failure may occur. If it exceeds 160 ° C., wrinkles are likely to occur during thermocompression bonding. The temperature of the heat roll is more preferably 80 to 110 ° C.

The rotational speed of the hot roll is preferably 0.1 to 10 m / min. If it is less than 0.1 m / min, wrinkles may easily occur after thermocompression bonding. If it exceeds 10 m / min, adhesion failure may occur. The rotation speed of the heat roll is more preferably 0.3 to 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 flexible base material side surface, for example, in the same manner as described above, the solar cell protective sheet is disposed on the flexible base material side surface of the solar cell, and the adhesive sealing layer faces the flexible base material. And a method of thermocompression bonding by narrowing them using a pair of heat rolls.
The step of thermocompression bonding the solar cell protection sheet to the flexible substrate side surface of the solar cell may be performed before the step of thermocompression bonding the solar cell protection sheet on the light receiving surface of the solar cell element described above. May be performed simultaneously or later.

About an example of the method of manufacturing the flexible solar cell module of this invention using the said solar cell protective sheet, for example, sealing the photoelectric conversion layer side surface and flexible base material side surface of a solar cell element simultaneously, FIG. Will be described.
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 cut into a desired shape are prepared, the adhesive sealing layer of the solar cell protective sheet, and the above In the state where the photoelectric conversion layer side surface of the solar cell element or both surfaces are opposed, the solar cell protection sheet and the solar cell element are laminated, and the obtained laminate is in a stationary state under reduced pressure. A method may be used in which 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.

Thus, the present invention reduces transparency and weather resistance by having a protective layer made of a fluoropolymer containing an epoxy group-containing compound and an adhesive sealing layer made of maleic anhydride-modified olefin resin. The flexible solar cell module is excellent in adhesion between the protective layer and the adhesive sealing layer and can be manufactured with high efficiency.

Since the flexible solar cell module of the present invention has the above-described configuration, the flexible solar cell module has excellent adhesion between the protective layer and the adhesive sealing layer, and can be manufactured with high efficiency.

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 protection sheet. 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.

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

(Examples 1-3, 6-9, 12-13)
The modified olefin resins obtained by graft-modifying predetermined olefin resins shown in Tables 1 and 2 with maleic anhydride were supplied to the first extruder and melt-kneaded at 250 ° C.
On the other hand, 100 parts by weight of a predetermined fluoropolymer resin (polyvinylidene fluoride, manufactured by Arkema, trade name “Kyner 720”) shown in Tables 1 and 2 and a predetermined amount of 3-glycidoxypropyltrimethoxysilane ( Protective layer comprising Toray Dow Corning, trade name “Z-6040”) or 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane (Shin-Etsu Chemical Co., trade name “KBM-303”) The composition for use was supplied to the second extruder and melt-kneaded at the preset extrusion temperatures shown in Tables 1 and 2.
Then, the modified olefin resin and the protective layer composition are supplied and joined to a joining die that connects the first extruder and the second extruder together, and the joining die is connected to the joining die. The sheet was extruded from a T die into a sheet, and the adhesive sealing layer made of the modified olefin resin having a thickness of 0.3 mm and the protective layer made of the protective layer composition having a thickness of 0.03 mm were laminated and integrated. A solar cell protective sheet having a long and constant width was obtained.
Tables 1 and 2 show the melt flow rate (MFR) of the modified olefin resin used and the maximum peak temperature (Tm) of the endothermic curve measured by differential scanning calorimetry. Tables 1 and 2 show the total maleic anhydride content in the modified olefinic resin.

Subsequently, the flexible solar cell module was produced in the following ways using the solar cell protective sheet obtained above.
First, on a flexible base material made of a flexible polyimide film, a photoelectric conversion layer made of a thin film-like amorphous silicon is formed, and a solar cell element wound in a roll shape, and A solar cell protective sheet in which the obtained solar cell protective sheet was wound into a roll was prepared.

Next, as shown in FIG. 5, 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 Tables 1 and 2, and the laminated sheet D is heated while pressing the laminated sheet D in the thickness direction thereof, thereby obtaining a solar cell. The photoelectric conversion layer was sealed by bonding and integrating the protective sheet B to the solar cell element C, and the flexible solar cell module A was continuously manufactured, and wound around a winding shaft (not shown).

(Examples 4-5, 10, 11, 14, 15)
To 100 parts by mass of the modified olefin resin, a predetermined amount of 3-glycidoxypropyltrimethoxysilane (made by Toray Dow Corning, trade name “Z-6040”) described in Tables 1 and 2 or 2- (3 A flexible solar cell module was obtained in the same manner as in Example 1 except that 4-epoxycyclohexyl) ethyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name “KBM-303”) was added.

(Comparative Examples 1 and 2)
The solar cell protective sheet obtained was used in the same manner as in Example 1 except that the silane compound was not added to the fluoropolymer and the adhesive sealing layer composition shown in Table 2 was used. A flexible solar cell module was obtained in the same manner as in Example 1 except that sealing was performed at the roll temperature.

About the obtained flexible solar cell module, the generation | occurrence | production condition of wrinkles, the generation | occurrence | production state of curl, peeling strength, delamination strength, and high temperature, high humidity durability were measured in the following way, and the result is shown in Table 1 and 2 It was.

<Occurrence of wrinkles>
The state of occurrence of wrinkles in the obtained flexible solar cell module was judged visually, and was scored according to the following score. 4 points or more pass.
5 points: No wrinkling was observed.
4 points: 1 wrinkle within 0.5 mm / m ^{2 is} found.
3 points: 2 to 4 wrinkles / m ² within 0.5 mm are found.
2 points: 5 wrinkles / m ² or more within 0.5 mm are found.
1 point: A large wrinkle of 0.5 mm or more is found.

<Occurrence of curls>
The flexible solar cell module having a size of 500 mm × 500 mm was placed on a flat plane, and the height of lifting from the horizontal plane at the end was measured.
◎: Less than 20 mm ○: 20 mm or more and less than 25 mm Δ: 25 mm or more and less than 35 mm x: 35 mm or more

<Peel strength>
In the obtained flexible solar cell module, the peel strength when the solar cell protective sheet was peeled from the solar cell element was measured according to JIS K6854.

<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.

<High temperature and high humidity durability>
The obtained flexible solar cell module was allowed to stand in an environment of 85 ° C. and a relative humidity of 85% described in JIC C8991, and the solar cell protective sheet was peeled off from the solar cell element after starting the above-mentioned leaving. Observation was made every 500 hours, and the time when peeling was confirmed was measured.
In JIC C8991, which defines the authentication conditions for solar cell modules, the durability of 1000 hours or more is required in terms of power generation efficiency, and it is determined that an article that has been confirmed to be peeled in less than 1000 hours has insufficient adhesion.

The present invention is a flexible solar cell module that has excellent adhesion between a protective layer and an adhesive sealing layer and can be manufactured with high efficiency.

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

Claims (5)

A flexible solar cell module comprising a protective layer made of a fluoropolymer containing an epoxy group-containing compound, an adhesive sealing layer made of a maleic anhydride-modified olefin resin, and a solar cell element. The flexible solar cell module according to claim 1, wherein the epoxy group-containing compound is an epoxysilane compound represented by the general formula (I).

(In the formula, R ¹ represents a 3-glycidoxypropyl group or 2- (3,4-epoxycyclohexyl) ethyl group, R ² represents an alkyl group having 1 to 3 carbon atoms, and R ³ Represents an alkyl group having 1 to 3 carbon atoms, and n is 0 or 1.) The flexible solar cell module according to claim 1, wherein the protective layer contains 0.001 to 3 parts by weight of the epoxy group-containing compound with respect to 100 parts by weight of the fluoropolymer. The maleic anhydride-modified olefin resin is a resin obtained by graft-modifying an olefin resin with maleic anhydride, and the total content of maleic anhydride is 0.005 to 3% by weight. 3. The flexible solar cell module according to 3. The adhesive sealing layer further contains 0.05 to 5 parts by weight of the epoxysilane compound represented by the general formula (I) with respect to 100 parts by weight of the maleic anhydride-modified olefin resin. Or the flexible solar cell module of 4.

(In the formula, R ¹ represents a 3-glycidoxypropyl group or 2- (3,4-epoxycyclohexyl) ethyl group, R ² represents an alkyl group having 1 to 3 carbon atoms, and R ³ Represents an alkyl group having 1 to 3 carbon atoms, and n is 0 or 1.)

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