JP2009071236A - Back sheet for solar battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a back sheet excellent in an ultraviolet removing function and visible light removing function, and to provide an adhesive layer excellent in adhesive strength between a first organic film and a second organic film. <P>SOLUTION: A back sheet for solar battery 30 comprises a first organic film 10 and a second organic film 11 adhered by an adhesion layer and the adhesion layer 20 contains a resin component 21 and an inorganic pigment component 22. The resin component 21 contains a diamine compound (A component) and a vinyl copolymer (B component). Preferably, the B component contains ethylene and an unsaturated carboxylic acid derivative having a functional group reactive with the A component. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to a solar cell backsheet used on the back surface (opposite the light receiving surface) of a solar cell.

A general solar cell is a single-sided light receiving type, and the configuration thereof is, for example, a transparent adhesive for a sealing film, a solar cell element, a transparent adhesive for a sealing film, and a glass plate sequentially laminated on a back sheet. It will be. Since the transparent adhesive for sealing films can be melted by heating and crosslinked and cured, the substrate, the solar cell element and the glass plate can be integrated by heat treatment.

Since solar cells are used outdoors, light resistance is required for the layers constituting the solar cells. In particular, the back sheet that protects the back surface of the solar cell is a part that comes into contact with water and water vapor, and also a surface that directly receives sunlight reflected light (hereinafter referred to as reflected light). In addition to being small, it is necessary to have excellent light resistance.

In this case, the back sheet according to the prior art is formed by adhering the first organic film and the second organic film through an adhesive layer, and has low water vapor permeability and light resistance. .

As shown in FIG. 2, in the solar cell using the back sheet, the glass plate 60 as the surface-side transparent protective member on the light receiving surface side, the first organic film 10, and the second organic film 11 are bonded to each other. The solar battery cell, that is, a solar battery element 50 such as silicon, is sealed between the solar battery backsheet 30 attached by the above-described transparent adhesives 40 and 41 for sealing film ( For example, see Patent Document 1).

JP 2000-174296 A

Although a fluororesin film has been proposed as the first organic film constituting the conventional backsheet, the fluororesin film transmits ultraviolet rays and visible light contained in the reflected light, so that the adhesive layer constituting the backsheet In addition, when the second organic film is irradiated with ultraviolet rays / visible rays for a long period of time, there is a problem that the respective layers are deteriorated.
In particular, when the adhesive layer is deteriorated, the adhesive strength between the first organic film and the second organic film to be adhered to the adhesive layer is reduced, which seriously hinders the reliability of the solar cell. there were.
On the other hand, when the second organic film is deteriorated, the second organic film itself becomes brittle, which causes a decrease in the adhesive force with the adhesive layer. In this case, as an initial sign of deterioration of the second organic film, the film itself may be yellowed.

The present invention relates to a back sheet used in the solar cell shown in FIG. 2, and an object of the present invention is to provide a back sheet excellent in ultraviolet ray removing action and visible light removing action.
Moreover, an object of this invention is to provide the contact bonding layer excellent in the adhesive strength with a 1st organic film and a 2nd organic film.
Furthermore, an object of the present invention is to provide a back sheet excellent in long-term stability.

The present invention is a solar cell backsheet characterized in that a first organic film and a second organic film are adhered by an adhesive layer, and the adhesive layer contains a resin component and an inorganic pigment component. is there.

In the adhesive layer, the amount of the resin component is preferably 20 to 99% by weight, and the inorganic pigment component is preferably 1 to 80% by weight.

The inorganic pigment component is preferably titanium dioxide.

It is preferable that the adhesive layer contains an ultraviolet absorber.

The first organic film is preferably a fluororesin film.

The resin component contains a diamine compound (component A) and a vinyl copolymer (component B), and the component B includes ethylene and an unsaturated carboxylic acid derivative having a functional group capable of reacting with the component A. It is preferable.

The component A preferably has a siloxane bond.

（式中のＲ^１は、炭素数１〜１０のアルキレン基を表し、ｍおよびｎは０〜１０の整数を示す） The component A is preferably a siloxane compound having amino groups at both ends represented by the following general formula (1) or the following general formula (2).

(R ¹ in the formula represents an alkylene group having 1 to 10 carbon atoms, and m and n represent an integer of 0 to 10)

The component B is a vinyl copolymer having ethylene and an unsaturated carboxylic acid having a functional group capable of reacting with the diamine compound or a derivative thereof, and the vinyl copolymer preferably has a glycidyl group. .

According to the present invention, a back sheet having an ultraviolet ray removing action and a visible light ray removing action can be provided by blending an inorganic pigment component into the adhesive layer constituting the invention.
Moreover, according to this invention specified by Claim 6, a back sheet | seat with big adhesive strength with a 2nd organic film can be provided.

Hereinafter, the present invention will be described with reference to the drawings.
The back sheet 30 in the present invention is a member that protects the back side (the side that receives the reflected light) of the single-sided light-receiving solar cell. As shown in FIG. 1, the first organic film 10 and the second organic film 11 is characterized in that a resin component 21 and an inorganic pigment component 22 are contained in the adhesive layer 20 in a laminated structure through the adhesive layer 20.

The adhesive layer 20 constituting the present invention contains a resin component 21 and an inorganic pigment component 22. Since the inorganic pigment component 22 used in the present invention has a property of not transmitting or preventing transmission of ultraviolet rays and visible light, it is not preferable to use it as a member for protecting the surface of the solar cell. It is necessary to use as

The thickness of the adhesive layer 20 is not particularly limited, but is preferably 1 to 100 μm. It is more preferable to set it as 5-50 micrometers, and it is especially preferable to set it as 10-30 micrometers.
If it is less than 1 μm, the adhesive strength between the first organic film and the second organic film tends to be insufficient. Moreover, although it is excellent in the adhesive force with these films when it exceeds 100 micrometers, when providing an adhesive layer by coating, the adhesive layer must be formed several times and is complicated.
Hereinafter, materials constituting the present invention will be described.

<Inorganic pigment component>
Examples of the inorganic pigment component include basic lead carbonate, basic lead sulfate, basic lead silicate, zinc white (specific gravity 5.47 to 5.61), zinc sulfide (specific gravity 4.1), lithopone, and triacid value. Antimony (specific gravity 5.5-5.6), diacid value titanium (specific gravity 4.2), graphite (specific gravity 3.3) can be mentioned. These components may be used alone or in combination of two or more.
As the inorganic pigment component, it is preferable to use titanium dioxide or zinc sulfide as a main component. In particular, titanium dioxide can be suitably used as a material contained in the adhesive layer, has a strong action of removing ultraviolet rays (light having a wavelength of 400 nm or less), and has an action of removing visible light.
Diacid-valent titanium is classified into a tetragonal type and an orthorhombic type depending on the crystal lattice. Tetragonal type further includes anatase type (low temperature type) and rutile type (high temperature type), and orthorhombic type includes brookite type. In the present invention, it is preferable to use a rutile-type titanium diacid value titanium in which the photocatalytic action is inactivated.

The shape of the inorganic pigment component may be a spherical structure, an elliptical structure, a needle-like structure, a polygonal structure, or an amorphous structure.

The particle size of the inorganic pigment component is not particularly limited as long as it is smaller than the thickness of the adhesive layer. For example, when the thickness of the adhesive layer is about 10 to 30 μm, the particle size is 0.01. By setting the thickness to about 3.0 μm, the adhesive force between the first organic film and the second organic film can be suitably maintained.

The inorganic pigment component blended in the adhesive layer may be 1 to 80% by weight. 5 to 60% by weight is preferable, and 10 to 50% by weight is more preferable.
If it is less than 1% by weight, it is difficult to suppress the light transmittance of ultraviolet rays and / or visible light, and if it exceeds 80% by weight, the adhesive strength between the second organic film and the first organic film may be reduced. There is.

The inorganic pigment component used in the present invention is preferably increased in specific gravity because the bulk of the inorganic pigment component contained in the adhesive layer is reduced. Thereby, since the area which the resin component contained in an contact bonding layer, and a 1st organic film and a 2nd organic film contact increases, adhesive force can be maintained suitably. Therefore, the specific gravity of the inorganic pigment component used in the present invention is preferably large. Specifically, the specific gravity is preferably 2.5 or more, and more preferably 3.0 or more.

<Resin component>
The compounding amount of the resin component in the adhesive layer is preferably 20 to 99% by weight. It is more preferable that it is 40 to 95 weight%, and it is especially preferable that it is 50 to 90 weight%.
If it is less than 20% by weight, the adhesive strength between the first organic film and the second organic film may not be suitably maintained.
The resin component to be included in the adhesive layer is, for example, epoxy resin, phenol resin, styrene block copolymer, polyamide resin, acrylic resin, acrylonitrile-butadiene copolymer, vinyl copolymer, polyester resin, polyimide resin, silicone resin. An adhesive mainly composed of one or more resins selected from amine compounds, bismaleimide compounds, and the like can be used.

The resin component constituting the adhesive layer contains a diamine compound (component A) and a vinyl copolymer (component B), and the component B is an unsaturated carboxylic acid having a functional group capable of reacting with ethylene and the component A. It is preferable to include a derivative.
By containing these components, the adhesive force with a 1st organic film and a 2nd organic film can be maintained suitably.
Further, the adhesive layer containing the A component and the B component is less susceptible to yellowing under heating conditions and under ultraviolet irradiation, and is suitable for use as a solar cell backsheet that is used for a long period of time.

[Component A]
In the present invention, the component A is both as shown in the structural formula [H ₂ N—R ² —NH ₂ ] (wherein R ² represents a divalent aliphatic group, aromatic group or alicyclic group). Any compound having an amino group at the terminal may be used.

Examples of the component A include 3,3′-diaminobiphenyl, 3,4′-diaminobiphenyl, 4,4′-diaminobiphenyl, 3,3′-diaminodiphenylmethane, 3,4′-diaminodiphenylmethane, 4,4 '-Diaminodiphenylmethane, 2,2- (3,3'-diaminodiphenyl) propane, 2,2- (3,4'-diaminodiphenyl) propane, 2,2- (4,4'-diaminodiphenyl) propane, 2,2- (3,3′-diaminodiphenyl) hexafluoropropane, 2,2- (3,4′-diaminodiphenyl) hexafluoropropane, 2,2- (4,4′-diaminodiphenyl) hexafluoropropane 3,3′-oxydianiline, 3,4′-oxydianiline, 4,4′-oxydianiline, 3,3′-diaminodiphenyl sulfide, 3,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 1,3-bis [1- (3-aminophenyl) -1-methylethyl] benzene, 1,3-bis [1- (4-aminophenyl) -1-methylethyl] benzene, 1,4-bis [1- (3- Aminophenyl) benzene, 1,3-bis (3-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (3-aminophenoxy) benzene, 1,4-bis ( 4-aminophenoxy) benzene, 3,3′-bis (3-aminophenoxy) diphenyl ether, 3,3′-bis (4-aminophenoxy) diphenyl ether Ether, 3,4′-bis (3-aminophenoxy) diphenyl ether, 3,4′-bis (4-aminophenoxy) diphenyl ether, 4,4′-bis (3-aminophenoxy) diphenyl ether, 4,4′-bis (4-aminophenoxy) diphenyl ether, 1,4-bis [1- (4-aminophenyl) -1-methylethyl-bis (3-aminophenoxy)] biphenyl, 3,3′-bis (4-aminophenoxy) Biphenyl, 3,4'-bis (3-aminophenoxy) biphenyl, 3,4'-bis (4-aminophenoxy) biphenyl, 4,4'-bis (3-aminophenoxy) biphenyl, 4,4'-bis (4-aminophenoxy) biphenyl, bis [4- (3-aminophenoxy) phenyl] sulfone, bis [4- (4-aminophenoxy) Phenyl] sulfone, 2,2-bis [3- (3-aminophenoxy) phenyl] propane, 2,2-bis [3- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (3 -Aminophenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [3- (3-aminophenoxy) phenyl] hexafluoropropane, 2,2- Bis [3- (4-aminophenoxy) phenyl] hexafluoropropane, 2,2-bis [4- (3-aminophenoxy) phenyl] hexafluoropropane, 2,2-bis [4- (4-aminophenoxy) Phenyl] hexafluoropropane, 9,9-bis (3-aminophenyl) fluorene, 9,9-bis (4-aminophenyl) fluorene, Tiger diamine, hexamethylene diamine, mention may be made of a heptamethylene diamine.

The component A preferably has a siloxane bond. Since the adhesive layer after curing repels moisture, the moisture absorption rate of the adhesive layer decreases. Accordingly, since the amount of moisture that permeates through the second organic film is reduced, the moisture is less likely to come into contact with the sealing film transparent adhesive laminated on the second organic film. Thereby, white turbidity of the transparent adhesive for sealing film caused by moisture contact can be reduced.
The component A having a siloxane bond is particularly preferably at least one selected from the compound group represented by the following general formula (1) or general formula (2).

（式中のＲ^１はそれぞれ独立に炭素数１〜１０のアルキレン基を表し、ｍおよびｎはそれぞれ独立に０〜１０の整数を示す。）

(R ¹ in the formula independently represents an alkylene group having 1 to 10 carbon atoms, and m and n each independently represents an integer of 0 to 10)

In formula (1), the alkylene group for R ¹ may be linear or branched, and is particularly preferably a linear alkylene group having 2 to 5 carbon atoms.
As m, the integer of 3-8 is preferable.
n is preferably an integer of 0 to 8.

As a siloxane compound having an amino group at both ends represented by the above general formula (1) or (2), product names: TSL9306 (diaminodisiloxane) manufactured by Toshiba Silicone Co., Ltd., product names: TSL9886 (diaminopoly) Siloxane), trade name: TSF4706 (diaminodisiloxane), trade name: XF42-A2645 (diaminopolysiloxane), and the like.

The content of the component A in the adhesive layer of the present invention is preferably 1 to 20% by weight, more preferably 1 to 15% by weight, and more preferably 1 to 10% by weight of the total solid content of the resin component constituting the adhesive layer. Further preferred. If it is less than 1% by weight, crosslinking with the component B becomes insufficient, and the adhesive force cannot be suitably maintained. If it exceeds 20% by weight, the crosslinking with the component B proceeds too much, so that the adhesive layer becomes too hard, and the adhesive force cannot be suitably maintained.

[B component]
Component B is a vinyl copolymer containing ethylene and an unsaturated carboxylic acid derivative having a functional group capable of reacting with the diamine compound.
The vinyl copolymer constituting the present invention includes at least ethylene and an unsaturated carboxylic acid derivative having a functional group capable of reacting with the diamine compound as main monomer components. A small amount of monomer may be contained.
Here, the monomer component means a compound that forms a repeating unit of the polymer when it is polymerized by a polymerization reaction to form a polymer. For example, a polymer containing ethylene as a monomer component contains a repeating unit represented by the formula — [CH ₂ —CH ₂ ] — formed by cleavage of a double bond of ethylene.

Examples of the functional group capable of reacting with the diamine compound include an aldehyde group, an aminoformaldehyde group, an isocyanate group, a carboxyl group, a glycidyl group, a maleimide group, and a bismaleimide group. Among them, a glycidyl group is preferable because of its high reactivity. Particularly preferred functional groups are a carboxyl group and a glycidyl group.
As unsaturated carboxylic acid which has these groups, or its derivative (s), the following are mentioned, for example. Examples of those having a carboxyl group include olefins such as acrylic acid, methacrylic acid, (anhydrous) maleic acid, and propylene having a carboxyl group. Examples of those having a glycidyl group include glycidyl acrylate and glycidyl methacrylate.

In the present invention, the vinyl copolymer is preferably ethylene- (meth) acrylic acid alkyl ester-glycidyl (meth) acrylate copolymer, ethylene-glycidyl (meth) acrylate copolymer, ethylene-glycidyl (meta ) Acrylate-vinyl acetate copolymer. Among these, ethylene- (meth) acrylic acid alkyl ester-glycidyl (meth) acrylate copolymer and ethylene-glycidyl (meth) acrylate copolymer are preferable. In the adhesive layer constituting the present invention, it is also preferable to use two or more of the above vinyl copolymers in combination.

The vinyl copolymer can impart flexibility to the adhesive layer, and preferably contains an ethylene- (meth) acrylate as described above. A copolymer containing an ethylene- (meth) acrylic acid ester does not contain a diene bond in the main chain, so that it does not easily cause thermal deterioration (no elasticity) even at high temperatures and can maintain stress relaxation over a long period of time. .
In addition, since it has an ester bond in the side chain, it has relatively high solubility in organic solvents and is difficult to hydrolyze, so it can be used for sealing films bonded to the adhesive layer even in high-temperature and high-humidity environments. The white turbidity of the resin is suppressed, and it can be used as a solar cell for a long time. In this case, the monomer ratio of the acrylic ester is preferably 5 to 40 mol%. If it is less than 5 mol%, the solubility in an organic solvent is extremely lowered, so that it is unsuitable for a coating solution (paint). Moreover, when it exceeds 40 mol%, it becomes easy to produce a hydrolysis of a contact bonding layer and it is easy to produce the cloudiness of resin for sealing films.

In the component B, the proportion of ethylene is preferably 40% by weight or more, and more preferably 50 to 98% by weight, based on the total of all monomer components contained in the resin component.
In the component B, the content of the unsaturated carboxylic acid derivative in the vinyl copolymer in the resin component is preferably 0.1 to 40% by weight, and more preferably 0.8 to 20% by weight. When the content of the unsaturated carboxylic acid derivative component in the copolymer is less than 0.1% by weight, the reactivity with the component A or the component B is low, and the solubility in an organic solvent is also low. On the other hand, if the content exceeds 40% by weight, the stability in the paint state tends to deteriorate. Further, when the third monomer is present, its content is 40% by weight or less, more preferably 30% by weight or less.
The total amount of ethylene and unsaturated carboxylic acid derivative is preferably 40 to 98% by weight based on the total of all monomer components.

The content of the component B in the adhesive layer of the present invention is preferably 80 to 99% by weight, more preferably 80 to 95% by weight, and 85 to 95% by weight of the total solid content of the resin component constituting the adhesive layer. More preferred is 90 to 95% by weight. If it is less than 80% by weight, the adhesive layer tends to be hard and the adhesive force cannot be suitably maintained. If it exceeds 99% by weight, the crosslinking with the component A becomes insufficient and the adhesive strength cannot be suitably maintained.

[Other optional ingredients]
The adhesive layer of the present invention can contain the following optional components in order to improve the adhesion between the first organic film and the second organic film after film formation and the adhesive layer.

The adhesive layer of the present invention may contain an epoxy resin, an epoxy curing agent, a phenol resin, and a coupling agent. By containing these, the curing reaction of the adhesive layer of the present invention is promoted, and the heat resistance as the adhesive layer is improved.

Examples of the epoxy resin include bifunctional epoxy resins such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, and naphthalene type epoxy resin, triglycidyl isocyanurate type epoxy resin, and triglycidyl-p-aminopheno. Polyfunctional glycidylamine type epoxy resin such as tetra-type epoxy resin, tetraglycidyl diaminodiphenylmethane type epoxy resin, tetraglycidyl metaxylenediamine type epoxy resin, tetraglycidyl-1,3-bisaminomethylcyclohexane type epoxy resin, tetra Polyfunctional glycidyl ether type epoxy resin such as phenyl glycidyl ether ethane type epoxy resin, triphenyl glycidyl ether methane type epoxy resin, phenol type epoxy resin Resins, polyfunctional resol type epoxy resins such as alkylphenol type epoxy resin, cyclopentadiene type epoxy resin, biphenyl type epoxy resin, phenol epoxy resins, such as a polyfunctional novolak epoxy resins and cresol type epoxy resins. These may be used alone or in combination of two or more.

As the epoxy curing agent, commonly used ones can be used. Specifically, amine catalysts such as imidazoles, 1,8-diazabicyclo (5,4,0) undecene, triphenylphosphine and the like can be used. A phosphorus catalyst etc. can be illustrated.

Examples of the phenol resin include phenol derivatives such as a resole phenol resin, a phenol novolak resin, a cresol novolac resin, a resorcinol resin, and a xylene resin. Among these, a phenol novolac resin is preferable because it has excellent reactivity and excellent moisture resistance and heat resistance.

Moreover, in order to improve the adhesiveness with a 1st organic film and a 2nd organic film, it is preferable to add a coupling agent to the contact bonding layer of this invention.
As the coupling agent, a silane coupling agent, a titanium coupling agent and an aluminum coupling agent are preferably used.

Furthermore, the adhesive layer of the present invention may contain an ultraviolet absorber for preventing deterioration due to ultraviolet irradiation, and may contain a dispersant for improving the dispersibility of the inorganic pigment component. In addition, various dye compounds may be included in the adhesive layer of the present invention, the amount of light transmission in a specific wavelength region can be reduced, and design properties are imparted to the backsheet.

The adhesive layer of the present invention can be formed by applying and drying a paint in which an inorganic pigment component and a resin component, which are essential components, are dissolved and dispersed in an organic solvent to an organic film. When other components are contained in the adhesive layer, they may be mixed when dissolved or dispersed in an organic solvent.
Preferred organic solvents include N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, pyridine, methyl ethyl ketone, methyl isobutyl ketone, toluene, xylene, 1,4-dioxane, tetrahydrofuran Several types and amounts such as ethanol, methanol, methyl cellosolve and the like can be appropriately selected and used.
The coating material is preferably prepared such that the solid content concentration is 5% by weight or more, and more preferably 10 to 50% by weight. When the solid content concentration is less than 5% by weight, the thickness of the adhesive layer tends to be uneven.

In the adhesive layer of the present invention, it is preferable that the adhesive layer-forming coating material is applied to an organic film and then subjected to heat treatment to volatilize the solvent. For example, when toluene is used as the solvent, it is preferably heated to about 100 to 135 ° C. If the temperature at this time is less than 100 ° C., the solvent may not sufficiently volatilize. The drying time may be adjusted according to the drying temperature. For example, when the drying temperature is 100 ° C., about 10 minutes is sufficient.

[First organic film]
As the first organic film constituting the back sheet of the present invention, a fluororesin film can be suitably used. Specifically, polytetrafluoroethylene (PTFE), 4-fluoroethylene-perchloroalkoxy copolymer (PFA), 4-fluoroethylene-6-fluoropropylene copolymer (FEP), 2-ethylene Examples include -4-fluoroethylene copolymer (ETFE), poly-3-fluoroethylene chloride (PCTFE), polyvinylidene fluoride (PVDF), and polyvinyl fluoride (PVF). These fluororesin films are excellent in light resistance and do not cause yellowing when irradiated with ultraviolet rays.
In the present invention, among fluororesin films, it is preferable to use PCTFE because of its extremely low water vapor transmission rate. In the present invention, the organic film having a low water vapor transmission rate means a film having a water vapor transmission rate of 1.0 g / m ² · 24 hr or less as a result of measurement according to JIS-K7126.

The thickness of the first organic film is preferably about 5 to 250 μm.

[Second organic film]
Examples of the second organic film constituting the backsheet of the present invention include polyester, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), acrylic resin, polycarbonate, polyimide, polyamide, polyamideimide, polyethersulfone, Examples thereof include polyphenylene sulfide, polyether ketone, polyether imide, triacetyl cellulose, silicone rubber, and a fluororesin film.

The thickness of the second organic film is preferably about 5 to 250 μm.
EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to this at all.
In addition, the part in an Example means a weight part.

An adhesive layer material having the following composition was dissolved in 170 g of toluene to prepare a coating material for forming an adhesive layer.
・ Rutyl type titanium oxide (particle diameter 0.25 μm, specific gravity 4.2) 3.8 parts ・ (A component) diaminodisiloxane (manufactured by Toshiba Silicone Co., Ltd., trade name: TSL9306) 3.0 parts ・ (B component) ethylene -Ethyl acrylate-maleic anhydride copolymer (manufactured by Sumitomo Atchem, trade name: Bondine A × 8390) 30.7 parts (solid content)

Next, a coating material composed of these components is applied onto a second organic film composed of a PET film having a thickness of 100 μm and dried at 100 ° C. for 10 minutes in a hot air circulation dryer, and the thickness is 19 μm. An adhesive layer was formed. Subsequently, an organic film made of a poly (3-fluoroethylene chloride) film having a thickness of 23 μm (trade name: NEOFLON PCTFE) having a thickness of 23 μm is laminated on the dried adhesive layer, and heated at 150 ° C. for 1 hour. The adhesive layer was cured to produce the back sheet of the present invention.
The poly-3-fluoroethylene chloride film laminated on the adhesive layer did not cover the entire adhesive layer so that the yellowing occurrence site could be recognized.

A back sheet was produced in the same manner as in Example 1 except that the thickness of the adhesive layer after drying was 22 μm.

Using the adhesive layer material having the following composition, the first organic film is made of 4-fluoroethylene-6-fluoropropylene copolymer (trade name: NEOFLON FEP manufactured by Daikin Industries, Ltd.) having a thickness of 50 μm. A back sheet was produced in the same manner as in Example 1 except that the film was used. The thickness of the adhesive layer after drying was 19 μm.
・ Rutyl type titanium oxide (particle diameter 0.25 μm, specific gravity 4.2) 7.5 parts (component A) diaminodisiloxane (trade name: TSL9886 manufactured by Toshiba Silicone) 3.0 parts (component B) ethylene- Glycidyl methacrylate copolymer (trade name: Bond First E, manufactured by Sumitomo Chemical Co., Ltd.) 27.0 parts

A back sheet was produced in the same manner as in Example 3 except that the thickness of the adhesive layer after drying was 22 μm.

A film made of 2-ethylene-4-fluoroethylene copolymer (trade name: NEOFLON ETFE, manufactured by Daikin Industries, Ltd.) having a thickness of 50 μm is used as the first organic film, using an adhesive layer material having the following composition. A back sheet was produced in the same manner as in Example 1 except that it was used. The thickness of the adhesive layer after drying was 19 μm.
・ Rutyl type titanium oxide (particle diameter 0.25 μm, specific gravity 4.2) 11.3 parts (component A) diaminodisiloxane (trade name: TSL9306 manufactured by Toshiba Silicone) 2.4 parts (component B) ethylene- Glycidyl methacrylate copolymer (trade name: Bond First E, manufactured by Sumitomo Chemical Co., Ltd.) 23.9 parts

A back sheet was produced in the same manner as in Example 5 except that the thickness of the adhesive layer after drying was 22 μm.

A back sheet was produced in the same manner as in Example 1 except that the adhesive layer material having the following composition was used. The thickness of the adhesive layer after drying was 15 μm.
・ Rutyl-type titanium oxide (particle diameter 0.25 μm, specific gravity 4.2) 15.0 parts ・ (Component A) diaminodisiloxane 2.0 parts ・ (Component B) ethylene-ethyl acrylate-maleic anhydride copolymer 20.5 parts

A back sheet was produced in the same manner as in Example 7 except that the thickness of the adhesive layer after drying was 22 μm.

A back sheet was produced in the same manner as in Example 1 except that the adhesive layer material having the following composition was used. The thickness of the adhesive layer after drying was 16 μm.
・ Rutyl type titanium oxide (particle diameter 0.25 μm, specific gravity 4.2) 18.8 parts (component A) diaminodisiloxane (manufactured by Toshiba Silicone Co., Ltd., trade name: TSL9306) 1.7 parts (component B) ethylene -Ethyl acrylate-maleic anhydride copolymer (manufactured by Sumitomo Atchem, trade name: Bondine A × 8390) 17.1 parts

A back sheet was produced in the same manner as in Example 9 except that the thickness of the adhesive layer after drying was 18 μm.

A back sheet was produced in the same manner as in Example 1 except that the adhesive layer material having the following composition was used.
Alumina (particle size 1.5 μm, specific gravity 4.0) 18.8 parts (component A) diaminodisiloxane (manufactured by Toshiba Silicone, trade name: TSL9306) 1.7 parts (component B) ethylene-acrylic acid 17.1 parts of ethyl-maleic anhydride copolymer (manufactured by Sumitomo Atchem, trade name: Bondine A × 8390)

[Comparative Example 1]
A back sheet was produced in the same manner as in Example 1 except that no titanium oxide was contained.
Table 1 summarizes the compounding ratios of the materials constituting the adhesive layer materials of Examples 1 to 11 and Comparative Example 1.

The following measurement items were evaluated for the back sheets of Examples 1 to 11 and Comparative Example 1.
(1) Ultraviolet ray removing action The ultraviolet ray removing action was confirmed by a method according to JIS-K7105.
That is, the ultraviolet ray removing action in the present embodiment and the like can be measured by the amount of light transmitted from the second organic film 11 side by irradiating 330 nm light from the first organic film 10 side constituting the back sheet 30. Quantitative determination was made from the relative value (%) of the amount of transmitted light when the light irradiation amount was 100%. The obtained results are shown in Table 2.
In addition, in this invention, the ultraviolet-ray removal effect | action is excellent means that the transmitted light amount by the said method is 10% or less. The amount of transmitted light is preferably 5% or less. When the amount of transmitted light is more than 10%, the adhesive layer 20 and the second organic film 11 are likely to deteriorate when the backsheet 30 is used for a long time.
(2) Visible light removing action The visible light removing action in this example and the like was measured by the total light transmittance according to JIS-K7105. The obtained results are shown in Table 2.
In addition, in this invention, that the visible light removal effect | action is excellent means that the total light transmittance by the said method is 50% or less. In general, the shorter the wavelength, the greater the amount of energy. Therefore, it is preferable that the visible light removing action has a lower transmitted light amount as the wavelength is shorter.
(3) Near-infrared ray removing action The near-infrared ray removing action in this example and the like is measured by a method according to JIS-K7105, and can be determined by irradiating light of about 800 to 1000 nm. In general, since the shorter the wavelength, the greater the amount of energy, it is preferable that the near-infrared ray removing action as well as the visible light removing action have a lower transmitted light amount as the wavelength is shorter.
(4) Presence or absence of yellowing After irradiating ultraviolet rays for 120 hours on the first organic film surface of the backsheet produced in Examples 1 to 11 and Comparative Example 1 by a carbon arc test according to JIS-B7753, It was visually determined whether or not these backsheets were yellowed. The case where yellowing did not occur was marked with ○, and the case where yellowing occurred was marked with ×.

The backsheets of Examples 1 to 10 containing titanium oxide in the adhesive layer showed almost no light transmittance in ultraviolet light (330 nm), and any total light transmittance was 50% or less. Also in the carbon arc test, yellowing was not recognized in the adhesive layer and the second organic film, and it was confirmed that the film had excellent light resistance.
Also for the back sheet of Example 11 in which alumina was contained in the adhesive layer, the ultraviolet light and total light transmittance could be reduced.
On the other hand, Comparative Example 1 in which the inorganic pigment component was not contained in the adhesive layer produced yellowing in the carbon arc test.

As described above, according to the present invention, since an adhesive layer containing an inorganic pigment component is used, it is possible to provide a back sheet excellent in ultraviolet ray removing action and visible ray removing action.
Moreover, the back sheet | seat excellent in the adhesive strength with a 1st organic film and a 2nd organic film can be provided by using A component and B component for the resin component which comprises the said contact bonding layer.
Furthermore, according to the present invention, a back sheet excellent in long-term stability can be provided.

It is sectional drawing which shows the solar cell backsheet of this invention. It is sectional drawing of the solar cell to which the solar cell backsheet of this invention is applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 1st organic film 11 2nd organic film 20 Adhesive layer 21 Resin component 22 Inorganic pigment component 30 Back sheet 40, 41 Transparent adhesive 50 for sealing films Solar cell element 60 Glass plate 70 Solar cell

Claims (9)

A back sheet for a solar cell, wherein a first organic film and a second organic film are adhered by an adhesive layer, and the adhesive layer contains a resin component and an inorganic pigment component. 2. The solar cell backsheet according to claim 1, wherein the adhesive layer contains 20 to 99 wt% of the resin component and 1 to 80 wt% of the inorganic pigment component. . The solar cell backsheet according to claim 1, wherein the inorganic pigment component is titanium dioxide. The solar cell backsheet according to claim 1, wherein the adhesive layer contains an ultraviolet absorber. The solar cell backsheet according to claim 1, wherein the first organic film is a fluororesin film. The resin component contains a diamine compound (component A) and a vinyl copolymer (component B), and the component B includes ethylene and an unsaturated carboxylic acid derivative having a functional group capable of reacting with the component A. The solar cell backsheet according to claim 1. The said A component has a siloxane bond, The solar cell backsheet of Claim 6 characterized by the above-mentioned. 8. The solar cell backsheet according to claim 6, wherein the component A is a siloxane compound having amino groups at both ends represented by the following general formula (1) or the following general formula (2). .

(R ¹ in the formula represents an alkylene group having 1 to 10 carbon atoms, and m and n represent an integer of 0 to 10) The B component is a vinyl copolymer having ethylene and an unsaturated carboxylic acid having a functional group capable of reacting with the diamine compound or a derivative thereof, wherein the vinyl copolymer has a glycidyl group. The solar cell backsheet according to claim 6.

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