JP2012216805A - Solar cell module filler sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solar cell module filler sheet which excels in adhesion with solar cell elements and in durability and heat resistance, making it possible to manufacture a solar cell module with high efficiency.SOLUTION: A solar cell module filler sheet A includes an adhesive layer 2 on both sides of an intermediate layer 1. The intermediate layer 1 comprising low-density polyethylene resin having a melting point of 90 to 130°C or linear low-density polyethylene resin having a melting point of 90 to 130°C. The adhesive layer 2 comprising at least one kind of thermoplastic resin selected from the group consisting of acid modified polyolefin, silane modified polyolefin, ionomer, and ethylene-(meth)acrylic acid copolymer. A ratio in thickness of the adhesive layer 2 to the intermediate layer 1 (adhesive layer/intermediate layer) is 20/80 to 70/30.

Description

The present invention relates to a solar cell module filler sheet that is excellent in adhesiveness with a solar cell element, durability, and heat resistance, and that can produce a solar cell module with high efficiency.

In recent years, solar cells have been attracting attention as a clean energy source as the awareness of environmental issues and energy issues has increased. Currently, solar cell modules having various forms have been developed and proposed.

Such a solar cell module is generally composed of a transparent protective material, a filler sheet, a solar cell element as a photovoltaic element, a filler sheet, a back surface protective material, and the like. Then, these members are sequentially laminated, and manufactured by a lamination method or the like in which vacuum suction is performed and thermocompression bonding is performed.

In these members, the filler sheet is a layer for protecting the solar cell element in which the solar cell absorbs sunlight and generates electric power, and also maintains the performance and strength of the solar cell element and the solar cell module. And a layer for adhering a transparent protective material for maintaining durability and a back surface protective material. For this reason, the said filler sheet | seat needs the adhesiveness with a solar cell element, a transparent protective material, and a back surface protective material, durability, heat resistance, etc. of filler material itself. Further, in the manufacturing process such as the above-described lamination method, there is a need for vacuum lamination suitability that does not generate wrinkles and the like and can manufacture a solar cell module by suitably sealing a solar cell element.

Conventionally, ethylene-vinyl acetate resin (EVA) has been used as such a filler sheet (Patent Document 1). EVA can also exhibit excellent heat resistance by crosslinking in the step of bonding to the solar cell element. However, this cross-linking process has a problem that the manufacturing time becomes long. Moreover, there also existed a problem that the acetic acid contained in EVA contaminates the light emitting layer and transparent electrode layer of a solar cell element.

For this reason, the use of a non-EVA resin has been studied as a filler sheet.
For example, Patent Document 2 discloses 1 selected from the group consisting of a copolymer of an α-olefin and an ethylenically unsaturated silane compound or a modified or condensed product thereof, a light-resistant material, an ultraviolet absorber, and a heat stabilizer. It is described that a resin film made of a resin composition containing seeds or two or more kinds is used as a filler sheet that is laminated on the front surface side and the back surface side of a solar cell element.

However, with the filler sheet made of a non-EVA resin proposed to date, it has been difficult to achieve both adhesion to the solar cell element and high heat resistance within a short manufacturing time.

JP 7-297439 A JP 2004-214641 A

In view of the present situation, the present invention provides a solar cell module filler sheet that is excellent in adhesiveness, durability, and heat resistance with a solar cell element, and that can manufacture a solar cell module with high efficiency. Objective.

The present invention has an adhesive layer on both surfaces of an intermediate layer, and the intermediate layer is a low-density polyethylene resin having a melting point of 90 to 130 ° C, or a linear low-density polyethylene having a melting point of 90 to 130 ° C. The adhesive layer is made of at least one thermoplastic resin selected from the group consisting of acid-modified polyolefin, silane-modified polyolefin, ionomer, and ethylene- (meth) acrylic acid copolymer, A solar cell module filler sheet characterized in that the thickness ratio of the adhesive layer to the intermediate layer (adhesive layer / intermediate layer) is 20/80 to 70/30.
The present invention is described in detail below.

The solar cell module filler sheet of the present invention comprises an intermediate layer made of a specific component and an adhesive layer located on both sides thereof, and the ratio of the thickness of the adhesive layer to the intermediate layer is within a certain range. By doing so, a solar cell module excellent in adhesiveness, durability and heat resistance can be efficiently produced.
That is, the inventors of the present invention consisted of a conventional single-layer filler sheet consisting of a low density polyethylene resin having a specific range of melting point or an intermediate layer made of a linear low density polyethylene resin, and specific components on both sides thereof. By having a three-layer structure with an adhesive layer, and by making the ratio of the thickness of the adhesive layer and the intermediate layer within a certain range, thermal contraction is prevented during thermocompression bonding in the manufacturing process of the solar cell element module. In addition, because of its excellent adhesiveness, it has been found that it is excellent in suitability for vacuum lamination, can efficiently produce a solar cell module, and can be excellent in heat resistance and durability, and completes the present invention. It came to.
In addition, the filler sheet of the present invention having a specific three-layer structure can also suppress the occurrence of curl due to strain during processing due to rapid heating and cooling, particularly when used in the manufacture of flexible solar cell modules. it can.

The filler sheet for a solar cell module of the present invention has an intermediate layer made of a low density polyethylene resin or a linear low density polyethylene resin.
In the present specification, the low density polyethylene resin means a crystalline thermoplastic resin in which ethylene as a repeating unit is randomly branched and bonded. The low density polyethylene resin has a soft property that the crystallization does not proceed so much due to its branched structure, and the melting point is relatively low.
In the present specification, the linear low density polyethylene resin means that a repeating unit of ethylene and a slight amount of α-olefin (for example, propylene, 1-butene, 1-hexene, 4-methylpentene, 1-octene, etc.) are used together. It means a polymerized thermoplastic resin.

Since the low-density polyethylene resin or the linear low-density polyethylene resin maintains transparency at the time of lamination, it has a property that it is difficult to prevent the transmission of sunlight to the solar cell element. Moreover, since it is excellent in adhesiveness with the thermoplastic resin which comprises the said adhesive bond layer, interface peeling does not arise between adhesive bond layers. Furthermore, since it has moderate flexibility and waist, it is resistant to cracking and can be prevented from curling due to heat shrinkage.
By having such an intermediate layer made of low-density polyethylene resin or linear low-density polyethylene resin, the solar cell module filler sheet of the present invention is excellent in adhesion, durability and heat resistance to the solar cell element. A solar cell module can be manufactured with high efficiency.

The lower limit of the melting point of the low density polyethylene resin or linear low density polyethylene resin constituting the intermediate layer is 90 ° C., and the upper limit is 130 ° C. When the melting point is less than 90 ° C., the heat resistance is not sufficient, and wrinkles and curls due to thermal shrinkage occur during thermocompression bonding in the manufacturing process of the solar cell element module. If it exceeds 130 ° C., the adhesiveness becomes insufficient during thermocompression bonding in the manufacturing process of the solar cell element module. The minimum with said preferable melting | fusing point is 100 degreeC, and a preferable upper limit is 120 degreeC.
In addition, the said melting | fusing point is the maximum peak temperature (Tm) of the endothermic curve measured by differential scanning calorimetry, and is a value obtained by measuring based on the measuring method prescribed | regulated to JISK7121.

The density of the low-density polyethylene resin or linear low-density polyethylene resin constituting the intermediate layer is preferably 0.920 g / cm ³ or less. The low density polyethylene resin or linear low density polyethylene resin having a density of 0.920 g / cm ³ or less is superior in transparency due to its relatively low crystallinity, and exhibits the property of preventing the transmission of sunlight more easily. can do.
The density of the low density polyethylene resin or linear low density polyethylene resin is preferably 0.895 g / cm ³ or more.
In addition, the said density is a value obtained by the measuring method prescribed | regulated to JISK7112 (The measuring method of the density and specific gravity of a plastic).

The low-density polyethylene resin or linear low-density polyethylene resin constituting the intermediate layer preferably has a melt mass flow rate (MFR) of 3.0 g / 10 min or less. When the MFR exceeds 3.0 g / 10 min, durability may be reduced. The MFR is more preferably 2.5 g / 10 min or less. The lower limit of the MFR is preferably 0.5 g / 10 minutes.
The MFR is a value measured at a load of 2.16 kg in accordance with ASTM D1238.

A commercially available product may be used as the low-density polyethylene resin or the linear low-density polyethylene resin constituting the intermediate layer as long as the physical properties described above are satisfied.
As a commercial item of the said low density polyethylene resin, Novatec (trademark) YF30, LF488K (made by Nippon Polyethylene Co., Ltd.) etc. are mentioned, for example.
Commercially available products of the above linear low density polyethylene resin include, for example, Moretec (registered trademark) 0218CN (manufactured by Prime Polymer), Evolue (registered trademark) SP9010, SP4020 (manufactured by Prime Polymer), kernel KF260T (Nippon Polyethylene). Product), AFFINITY (registered trademark) PL1850 (manufactured by Dow), ENGAGE (registered trademark) 8003 (manufactured by Dow), and the like.

The intermediate layer may contain other additives other than the low density polyethylene resin or the linear low density polyethylene resin to the extent that the effects of the present invention are not affected. Examples of the other additives include an ultraviolet absorber, an antioxidant, a light stabilizer, a lubricant, and a pigment.

As a method of forming the intermediate layer, the low-density polyethylene resin or linear low-density polyethylene resin and an additive added as necessary are supplied to an extruder at a predetermined weight ratio and melted. Examples of the method include kneading and extruding into a sheet form from an extruder to form an intermediate layer.

The solar cell module filler sheet of the present invention has an adhesive layer on both surfaces of the intermediate layer.
Since the filler sheet for solar cell module of the present invention has a three-layer structure having a specific adhesive layer on both surfaces of such a specific intermediate layer, it is excellent in heat resistance, durability and adhesiveness.
The adhesive layer is made of at least one thermoplastic resin selected from the group consisting of acid-modified polyolefin, silane-modified polyolefin, ionomer, and ethylene- (meth) acrylic acid copolymer.
Among these, acid-modified polyolefin and silane-modified polyolefin are preferable, and acid-modified polyolefin is more preferable in terms of excellent adhesion to a solar cell element and vacuum laminate suitability.
The acid-modified polyolefin resin is more preferably a maleic anhydride-modified polyolefin resin.

Examples of the maleic anhydride-modified polyolefin 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, 1-hexene or 1-octene is preferred. That is, the α-olefin-ethylene copolymer is preferably a butene-ethylene copolymer, a hexene-ethylene copolymer, or an octene-ethylene copolymer.

The α-olefin-ethylene copolymer preferably has an α-olefin content of 1 to 25% by weight. If the α-olefin content is less than 1% by weight, wrinkles and curls may occur during the production of the solar cell module. When the α-olefin content exceeds 25% by weight, the adhesion to the solar cell element may be reduced. The more preferable lower limit of the α-olefin content is 10% by weight, and the more preferable upper limit is 20% by weight.

The content of the α-olefin in the α-olefin-ethylene copolymer can be determined from a spectrum integrated value of ¹³ C-NMR. Specifically, for example, when 1-butene is used, a spectral integrated value derived from a 1-butene structure obtained in the vicinity of 10.9 ppm, 26.1 ppm, and 39.1 ppm in deuterated chloroform, and 26.9 ppm. , 29.7 ppm vicinity, 30.2 ppm vicinity, 33.4 ppm vicinity, it calculates using the spectrum integral value derived from the ethylene structure. For spectral attribution, known data such as a polymer analysis handbook (edited by the Analytical Society of Japan, published by Asakura Shoten, 2008) may be used.

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 preferably has a total maleic anhydride content of 0.1 to 3% by weight. There exists a possibility that the adhesiveness of the filler sheet of this invention with respect to a solar cell element may fall that the total content of the said maleic anhydride is less than 0.1 weight%. When the total maleic anhydride content exceeds 3% by weight, the maleic anhydride-modified olefin resin is cross-linked, and the adhesiveness of the filler sheet of the present invention is lowered or the extrusion moldability is lowered. There is a fear. The more preferable lower limit of the total maleic anhydride content is 0.2% by weight, and the more preferable upper limit is 1.5% by weight, and more preferably less than 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 filler sheet of the present invention may be lowered. When the maximum peak temperature (Tm) of the endothermic curve is higher than 125 ° C., the heating time of the filler sheet becomes longer in the sealing step, and the productivity of the solar cell module is reduced, or the solar cell element There is a risk that sealing may be 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 mass flow rate (MFR) of 0.5 g / 10 min to 29 g / 10 min. If the MFR is less than 0.5 g / 10 min, the extrusion moldability of the filler sheet of the present invention may be lowered. If it exceeds 29 g / 10 minutes, the extrudability of the filler sheet may be reduced, and the thickness accuracy of the filler sheet may be reduced.
The MFR is more preferably 2 g / 10 min to 10 g / 10 min.
In addition, MFR of the said maleic anhydride modified olefin resin means the value measured by the load of 2.16kg based on ASTM D1238 which is a measuring method of MFR of a polyethylene-type 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 filler sheet of the present invention is lowered and the handleability is lowered, or the solar cell element is sealed with the filler sheet. When the solar cell module is manufactured by stopping, the filler sheet may need to be heated rapidly. When the viscoelastic storage elastic modulus at 30 ° C. is too low, the filler sheet exhibits adhesiveness at room temperature, and the handleability of the filler sheet may be lowered. Therefore, the lower limit is 1 ×. It is preferably 10 ⁷ Pa. 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 adhesiveness of the filler sheet of the present invention to the solar cell element may be lowered.
When the viscoelastic storage elastic modulus at 100 ° C. is too low, the filler sheet flows greatly due to the pressing force when the solar cell element is sealed with the filler sheet of the present invention to produce a solar cell module. And since the nonuniformity of the thickness of the said filler material sheet | seat 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.

Examples of the silane-modified polyolefin include a resin obtained by graft polymerization of an ethylenically unsaturated silane compound to a polyolefin in the presence of a radical generator.
Examples of the polyolefin include a copolymer of ethylene and α-olefin.
Examples of the α olefin include propylene, 1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene, vinyl acetate, acrylic acid, methacrylic acid, acrylic ester, and methacrylic ester. .
Examples of the ethylenically unsaturated silane compounds include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltripropoxysilane, vinyltriisopropoxysilane, vinyltributoxysilane, vinyltripentyloxysilane, vinyltriphenoxysilane, and vinyltribenzyl. Examples thereof include oxysilane, vinyltrimethylenedioxysilane, vinyltriethylenedioxysilane, vinylpropionyloxysilane, vinyltriacetoxysilane, and vinyltricarboxysilane.

The amount of the ethylenically unsaturated silane compound graft-polymerized to the polyolefin is preferably 0.1 parts by weight or more and less than 10 parts by weight with respect to 100 parts by weight of the polyolefin.

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.
As said ethylene-unsaturated carboxylic acid copolymer, the copolymer which consists of a copolymerization component of ethylene and unsaturated carboxylic acid at least is mentioned.
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 ionomer can be produced by a known method.

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 adhesive layer preferably further contains a silane compound having an epoxy group.
In particular, when the maleic anhydride-modified polyolefin resin is used, it is preferable to further contain the silane compound having the epoxy group.
By containing the said silane compound, the adhesiveness of the solar cell module filler sheet of this invention and a solar cell element can be improved.
The silane compound may have at least one epoxy group such as an aliphatic epoxy group or an alicyclic epoxy group in the molecule. The silane compound having an epoxy group 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 silane compound, 3-glycidoxypropyltrimethoxysilane and 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane are particularly preferable.

The content of the silane compound in the adhesive layer is preferably 0.1 to 15 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 filler sheet of this invention may fall that content of the said silane compound is outside the above-mentioned range.
The lower limit of the content of the silane compound is more preferably 0.15 parts by weight and the upper limit is more preferably 1 part by weight with respect to 100 parts by weight of the maleic anhydride-modified olefin resin.

The adhesive layer may further contain other additives as long as the physical properties are not impaired. 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.

As a method for forming the adhesive layer, the resin component described above, the silane compound, and an additive that is added as necessary are supplied to an extruder at a predetermined weight ratio, and melted and kneaded. Examples include a method of forming an adhesive layer by extruding into a sheet form from an extruder.

The adhesive layer is located on both surfaces of the intermediate layer, but when applied to a solar cell module, the adhesive layer on the front surface side that is the light receiving surface side and the adhesive layer on the back surface side are the ranges described above. As long as they are composed of these components, they may not be composed of exactly the same components, but they are preferably composed of the same components in that the effect of the present invention can be improved.

The solar cell module filler sheet of the present invention is formed by laminating the adhesive layer, the intermediate layer, and the adhesive layer in this order.
The total thickness of the filler sheet including these three layers is 100 to 600 μm.
There exists a possibility that adhesiveness and durability may be insufficient in the said total thickness being less than 100 micrometers. If the thickness exceeds 600 μm, the resin may protrude during thermocompression bonding in the manufacturing process of the solar cell element module. The lower limit of the total thickness is preferably 120 μm, and the upper limit is preferably 400 μm.

In the solar cell module filler sheet of the present invention, the thickness ratio of the adhesive layer to the intermediate layer (adhesive layer / intermediate layer) is 20/80 to 70/30. If it is less than 20/80, the adhesiveness tends to be insufficient. If it exceeds 70/30, wrinkles and curls due to thermal contraction are likely to occur during thermocompression bonding in the manufacturing process of the solar cell element module.
The lower limit of the thickness ratio is preferably 30/70, and the upper limit is preferably 60/40.
The thickness of the adhesive layer is preferably the same for both layers.

The method for producing the solar cell module filler sheet of the present invention can be produced by laminating and integrating the intermediate layer and the adhesive layer. The method for laminating and integrating is not particularly limited. For example, the intermediate layer and the adhesive layer may be formed by extrusion lamination on one surface of the adhesive layer, or the intermediate layer and the adhesive layer. Examples include a method of forming by coextrusion.
Among these, the method of forming by coextrusion is preferable.
In the case of forming by co-extrusion, the extrusion setting temperature is preferably 30 ° C. or higher than the melting point of the resin constituting the intermediate layer and the adhesive layer and less than 30 ° C. from the decomposition temperature.

The longitudinal cross-sectional schematic diagram which showed an example of the filler sheet | seat for solar cell modules of this invention is shown in FIG.
As shown in FIG. 1, the solar cell module filler sheet A of the present invention has an adhesive layer 2 on both surfaces of an intermediate layer 1.

Using the solar cell module filler sheet of the present invention, the solar cell element can be sealed to produce a solar cell module.
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 base material and a glass substrate as necessary.

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 200 μm.

The flexible substrate is not particularly limited as long as it is flexible and can be used for a flexible solar cell module. 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.

The glass substrate may be a glass substrate that can withstand the process of laminating the photoelectric conversion layer and the electrode material, and does not contain a substance that contaminates the photoelectric conversion layer when used as a solar cell. If it does not specifically limit, For example, soda-lime glass etc. are mentioned.
The thickness of the glass substrate is preferably 0.1 to 3 mm.

The electrode layer is a layer made of an electrode material.
The electrode layer may be on the photoelectric conversion layer as necessary, or may be between the photoelectric conversion layer and a flexible base material or a glass substrate, or on the flexible base material or the glass substrate surface. May be.
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 or 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, a method of forming a pn junction surface on a silicon wafer and printing the electrode and then firing, or the flexible substrate or glass It can form by well-known methods, such as the method of arrange | positioning the said photoelectric converting layer and electrode layer on a board | substrate.

As a method of sealing a solar cell element using the solar cell module filler sheet of the present invention, for example, the solar cell module filler sheet of the present invention is laminated above and below the solar cell element, and further, The laminate obtained by laminating the transparent protective material on the light-receiving surface side of the photoelectric conversion layer and the back surface protective material on the back surface side is heated in a stationary state under reduced pressure while applying a pressing force in the thickness direction. And the method of crimping | bonding the filler sheet for solar cell modules of this invention to the said solar cell element is mentioned. In addition, while a transparent protective material is laminated | stacked on the light-receiving surface side of a photoelectric converting layer, the aspect which does not laminate | stack a back surface protective material on the back surface side is also mentioned.
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.
The said solar cell element and the said solar cell module filler sheet | seat are good to use the rectangular thing adjusted to the desired magnitude | size previously.

The step of heating the laminate while applying a pressing force in the thickness direction under reduced pressure is preferably performed in a reduced pressure atmosphere of 1000 Pa or less, and more preferably in a reduced pressure atmosphere of 80 to 1000 Pa.
In the heating step, the laminate is preferably heated to 100 to 130 ° C, more preferably 100 to 120 ° C. The heating time is preferably 1 to 10 minutes, more preferably 2 to 5 minutes.

The said transparent protective material is a layer which can become the outermost layer by the side of the light-receiving surface of the photoelectric converting layer of a solar cell module.
The above-mentioned transparent protective material is excellent in transparency, heat resistance and flame retardancy. Glass, tetrafluoroethylene-ethylene copolymer (ETFE), ethylene chlorotrifluoroethylene resin (ECTFE), polychlorotrifluoroethylene Resin (PCTFE), polyvinylidene fluoride resin (PVDF), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (FEP), polyvinyl fluoride resin (PVF), and tetrafluoroethylene-hexafluoropropylene copolymer (FEP) It is preferable that it consists of fluorine resin, such as.

When the said transparent protective material consists of glass, it is preferable that the thickness of the said transparent protective material is 0.1-5 mm, and it is more preferable that it is 1.0-3.5 mm.
When the transparent protective material is made of a fluorine-based resin, the thickness of the transparent protective material is preferably 10 to 100 μm, and more preferably 15 to 80 μm.

The back surface protective material is a layer that can be the outermost layer on the back surface side of the solar cell module (that is, the side opposite to the light receiving surface of the photoelectric conversion layer).
The said back surface protection material may consist of resin sheets, such as glass, stainless steel, a polyvinyl fluoride / polyester / polyvinyl fluoride laminated sheet, a polyester / aluminum / polyester laminated sheet, in the point which is excellent in water vapor | steam barrier property and a weather resistance. preferable. In addition, the said back surface protection material does not need to be especially transparent.

When the said back surface protection material consists of glass or stainless steel, it is preferable that the thickness of the said back surface protection material is 0.1-5 mm, and it is more preferable that it is 1.0-3.5 mm.
When the said back surface protection material consists of laminated sheets, it is preferable that the thickness of the said back surface protection material is 10-500 micrometers, and it is more preferable that it is 100-300 micrometers.

The transparent protective material preferably has an embossed shape on the outermost surface. 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 is a step of embossing before the transparent protective material is bonded to the solar cell element, embossing after bonding to the solar cell element, or bonding with the solar cell element. You may mold at the same time.

The transparent protective material or the back protective material may have an adhesive layer on one surface. The transparent protective material or the back surface protective material is laminated so that the adhesive layer is in contact with the laminated body on the laminated body in which the solar cell module filler sheet of the present invention is laminated above and below the photoelectric conversion layer. Thereby, sealing can be made more reliable.

The adhesive layer is not particularly limited as long as it is made of a known component as a sealing material for solar cell elements. It is preferable that it consists of the same component as the adhesive layer of a material sheet.
The adhesive layer preferably has a thickness of 80 to 700 μm, and more preferably 150 to 400 μm.

The schematic diagram of an example of the structure of the solar cell module manufactured using the filler sheet for solar cell modules of this invention was shown in FIG.
In FIG. 2, the solar cell module filler sheet A having the adhesive layers 2 on both sides of the intermediate layer 1 is disposed above and below the solar cell element on which the photoelectric conversion layer 3 is formed on the substrate 4, A transparent protective material 5 and a back surface protective material 6 are arranged outside the filler sheet A for solar cell modules.
A solar cell module can be manufactured by heating a laminated body having such a configuration in a stationary state under reduced pressure while applying a pressing force in the thickness direction.

The solar cell module filler sheet of the present invention is excellent in adhesion, durability and heat resistance to solar cell elements. Further, since the thermal shrinkage is small, the solar cell element can be suitably sealed without generating wrinkles and the like, and a solar cell module can be manufactured efficiently.

The present invention is a solar cell module filler sheet excellent in adhesiveness, heat resistance and durability. For this reason, the solar cell module filler sheet of the present invention can be suitably used for the production of solar cell modules.

It is the longitudinal cross-sectional schematic diagram which showed an example of the filler sheet for solar cell modules of this invention. It is a schematic diagram of an example of a structure of the solar cell module manufactured using the filler sheet for solar cell modules.

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.

Example 1
A composition for an adhesive layer and an intermediate layer composition each having the composition shown in Table 2 were prepared, and co-extruded at 230 ° C., and the adhesive layer, the intermediate layer, and the adhesive layer were laminated in this order. A filler sheet was produced.
The two adhesive layers had a thickness of 30 μm, and the intermediate layer had a thickness of 90 μm.

(Examples 2 to 19, Comparative Examples 1 to 10)
Except having used the composition for adhesive layers and the composition for intermediate | middle layers which consist of a composition shown in Tables 2-4, and having made the thickness of an adhesive bond layer or an intermediate | middle layer into the numerical value of Tables 2-4, an Example In the same manner as in Example 1, a filler sheet was produced.

Table 1 shows the melting point, density, and MFR value of the thermoplastic resin constituting the intermediate layer used in the examples and comparative examples.
In Table 1, the density of the linear low density polyethylene resins F, H, and I represents the density measured according to ASTM D792, and the density of the cyclic polyethylene A represents the density measured according to ISO 1183. Others represent densities measured in accordance with JIS K7112.

Moreover, the materials shown in Tables 2 to 4 other than the thermoplastic resin constituting the intermediate layer are specifically as follows.
Modified butene resin: Adhesive Admer (registered trademark) XE070 (melting point: 89 ° C., density: 0.893 g / cm ³ , MFR: 3 g / 10 min, manufactured by Mitsui Chemicals, Inc.)
Silane-modified resin: Linkron (registered trademark) XLE815N (melting point 80 ° C., density: 0.915 g / cm ³ , MFR: 0.5 g / 10 min, manufactured by Mitsubishi Chemical Corporation)
Ionomer: Hi Milan (registered trademark) 1705 (melting point: 91 ° C., density: 0.95 g / cm ³ , MFR: 5.0 g / 10 min, manufactured by Mitsui DuPont)
Epoxy coupling agent: Z-6040 (manufactured by Dow Corning Toray)
Vinyl coupling agent: Z-6300 (Toray Dow Corning)
Amino coupling agent: Z-6011 (Toray Dow Corning)

(Evaluation)
About the obtained filler sheet, the breaking strength, accelerated weather resistance, curl measurement, heat shrinkage, adhesive strength, interlayer adhesion, transparency and heat durability were measured as follows, and the results are shown in Table 2 This is shown in FIG.

(1) Tensile strength at break Using Tensilon (manufactured by Toyo Seiki Seisakusho Co., Ltd.), the breaking strength of the prepared filler sheet was measured according to JIS K 6781, and the breaking strength was evaluated according to the following criteria.
A: The strength at break was 70 N or more.
A: The strength at break was 60 N or more and less than 70 N.
Δ: The strength at break was 50 N or more and less than 60 N.
X: The strength at break was less than 50N.

(2) Accelerated weather resistance Sunshine Super Long Life Weather Meter (manufactured by Suga Test Co., Ltd.) was used for irradiation for 800 hours under conditions of a black panel temperature of 63 ° C. and a water spray time of 12 minutes / 1 hour. Based on 6781, the elongation at break of the filler sheet was measured, and the accelerated weather resistance was evaluated according to the following criteria.
A: The elongation at break was 600% or more.
A: The elongation at break was 400% or more and less than 600%.
Δ: Elongation at break was 200% or more and less than 400%.
X: The elongation at break was less than 200%.

(3) Curl measurement The above filler sheet (50 cm × 50 cm) and a 38 μm thick biaxially stretched polyethylene terephthalate film (50 cm × 50 cm) in which photoelectric conversion layers made of amorphous silicon are arranged in parallel are vacuum laminated (80 ° C. , Heated at 150 seconds and pressed at 120 ° C. for 300 seconds), placed the resulting composite sheet on a flat table, measured the curl height, evaluated.
A: The curl height was less than 20 mm.
A: The curl height was 20 mm or more and less than 25 mm.
Δ: The curl height was 25 mm or more and less than 35 mm.
X: The curl height was 35 mm or more.

(4) Thermal shrinkage rate The above filler sheet was cut into 50 mm squares in both the MD and TD directions, and a “10” of 45 mm was drawn (dimension line) in the central portion of the sample for evaluation, and the length of each line was blank. Measure as
And after putting into 110 degreeC oven for 5 minutes, it takes out and the length of each said line in the time is measured. The ratio of the length after the blank and the oven was taken as the heat shrinkage rate, and evaluated according to the following criteria.
A: Shrinkage rate of TD was less than 5%.
○: Shrinkage of TD was 5% or more and less than 20%.
Δ: Shrinkage of TD was 20% or more and less than 50%.
X: Shrinkage of TD was 50% or more.

(5) Adhesive strength Laminate a transparent protective material made of polyvinylidene fluoride, the filler sheet and the solar cell element, and vacuum laminate (heat at 80 ° C. for 150 seconds and press at 120 ° C. for 300 seconds) ) To produce a solar cell module.
In the solar cell element, a photoelectric conversion layer made of thin-film amorphous silicon is formed on a flexible base material made of a flexible polyimide film.
In the produced solar cell module, the peel strength when the filler sheet was peeled from the substrate of the solar cell element was measured according to JIS K6854 and evaluated according to the following criteria.
A: Adhesive strength was 3 N / cm or more.
○: Adhesive strength was 2 N / cm or more and less than 3 N / cm.
Δ: Adhesive strength was 1 N / cm or more and less than 2 N / cm.
X: Adhesive strength was less than 1 N / cm.

(6) Interlayer adhesion Interlayer strength between the adhesive layer and the intermediate layer of the obtained filler sheet was evaluated according to the following criteria.
(Double-circle): Since the resin was integrated, there was no interlayer, and evaluation was impossible.
X: An interface existed and was easily peeled by hand (cannot be handled as a laminated film).

(7) Using a transparency haze meter (TC-HIII, manufactured by Tokyo Denshoku Co., Ltd.), the total light transmittance of the obtained filler sheet was measured by a method based on JIS-K7105, and evaluated according to the following criteria. did.
◎: Total light transmittance is 90% or more ○: Total light transmittance is 85% or more and less than 90% Δ: Total light transmittance is 80% or more and less than 85% ×: Total light transmittance is less than 80%

(8) Heat resistance durability The obtained filler sheet was sandwiched between stainless steel plates having a thickness of 5 mm and a size of 10 cm × 10 cm, and subjected to hot pressing at 120 ° C. for 10 minutes to obtain a laminate.
In the state which hold | maintained the obtained laminated body with the inclination of 30 degrees, the thermal test of 85 degreeC--40 degreeC defined by JIS-8991 was performed 200 cycles. After the cooling test, the deviation between the upper and lower stainless steel plates was measured and evaluated according to the following criteria.
A: The deviation of the stainless steel plate is less than 3 mm. A: The deviation of the stainless steel plate is 3 mm or more and less than 5 mm. Δ: The deviation of the stainless steel plate is 5 mm or more and less than 10 mm. X: The deviation of the stainless steel plate is 10 mm or more.

The solar cell module filler sheet of the present invention can be suitably used for the production of solar cell modules.

A Filler sheet for solar cell module 1 Intermediate layer 2 Adhesive layer 3 Photoelectric conversion layer 4 Base material 5 Transparent protective material 6 Back surface protective material

Claims (6)

Has an adhesive layer on both sides of the intermediate layer,
The intermediate layer is made of a low-density polyethylene resin having a melting point of 90 to 130 ° C, or a linear low-density polyethylene resin having a melting point of 90 to 130 ° C.
The adhesive layer is made of at least one thermoplastic resin selected from the group consisting of acid-modified polyolefin, silane-modified polyolefin, ionomer, and ethylene- (meth) acrylic acid copolymer,
The filler sheet for a solar cell module, wherein the thickness ratio of the adhesive layer to the intermediate layer (adhesive layer / intermediate layer) is 20/80 to 70/30. 2. The solar cell module filler sheet according to claim 1, wherein the low-density polyethylene resin or the linear low-density polyethylene resin has a density of 0.920 g / cm ³ or less. The filler sheet for a solar cell module according to claim 1 or 2, wherein the low-density polyethylene resin or the linear low-density polyethylene resin has a melt mass flow rate of 3.0 g / 10 min or less. The adhesive layer is a resin obtained by graft-modifying an α-olefin-ethylene copolymer having an α-olefin content of 1 to 25% by weight with maleic anhydride, and the total content of maleic anhydride is 0. The filler sheet for a solar cell module according to claim 1, comprising a maleic anhydride-modified polyolefin resin in an amount of from 1 to 3% by weight. The filler sheet for solar cell module according to claim 4, wherein the α-olefin is 1-butene, 1-hexene or 1-octene. The solar cell module according to claim 4 or 5, wherein the adhesive layer further contains 0.1 to 15 parts by weight of the silane compound represented by the general formula (I) with respect to 100 parts by weight of the maleic anhydride-modified polyolefin resin. Filler sheet.

(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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