JP2008282873A - Back sheet for solar cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a back sheet for solar cell wherein an adhesive layer having strong adhesive force with an organic film is adopted so as to make it harder to be peeled off from the organic film. <P>SOLUTION: The adhesive layer contains (A) epoxy resin, (B) phenol resin, (C) vinyl copolymer which contains an unsaturated carboxylic acid derivative having a functional group that can be reacted with ethylene and epoxy resin or epoxy curing agent, and (D) siloxane compound. It is stacked on the organic film. <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.

In recent years, solar energy has attracted attention from the viewpoint of effectively using resources, and development of solar cells that convert the energy into electric energy has been promoted.
A general solar cell is a single-sided light receiving type, and the configuration thereof is, for example, on a back sheet provided with an organic film on both surfaces of an aluminum foil, for a transparent adhesive for a sealing film, for a solar cell element, for a sealing film A transparent adhesive and a glass plate are sequentially laminated. 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, weather resistance is required for the layers constituting the solar cells. In particular, the back sheet for protecting the back surface of the solar cell is required to have excellent weather resistance and a low water vapor transmission rate. Thereby, since the cloudiness of the transparent adhesive for sealing films due to moisture can be prevented, the output of the solar cell element can be maintained over a long period of time.

Although the above aluminum foil has these properties, it is difficult to separate and collect only the aluminum foil after use, so it must be disposed of by incineration. However, at the time of the incineration, there was a problem that the remaining metal was clogged in the rostrol (grate) of the incinerator.

Therefore, solar cells using an aluminum film and using a back sheet made of an organic film and an adhesive layer are attracting attention. That is, as shown in FIG. 2, the solar battery is a solar battery cell between a glass substrate 60 as a surface-side transparent protective member on the light-receiving surface side and a back sheet 30 made of the adhesive layer 20 and the organic film 10, That is, the solar cell element 50 such as silicon is sealed through the sealing film transparent adhesives 40 and 41.
As this organic film, a fluororesin film having excellent weather resistance and a low water vapor transmission rate can be suitably used (for example, see Patent Document 1).
However, since the conventional backsheet has a weak adhesive force between the fluororesin film and the adhesive layer, there is a problem that the fluororesin film and the adhesive layer peel off when used for a long time as a backsheet for protecting the back surface of the solar cell. Was.

JP 2000-174296 A

The present invention relates to a back sheet used in the solar cell shown in FIG. 2, and by using an adhesive layer having excellent adhesive strength with an organic film, the organic film such as the fluororesin film and the adhesive layer are used. It aims at providing the solar cell backsheet (henceforth a backsheet) with large adhesive strength.
Another object of the present invention is to provide a back sheet having a low water vapor transmission rate.

（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）
前記有機フィルムがフッ素樹脂フィルムであることが好ましい（請求項３）。
前記フッ素樹脂フィルムが三フッ化塩化エチレン共重合体からなることが好ましい（請求項４）。
前記接着層がカップリング剤を含有することが好ましい（請求項５）。
前記接着層がエポキシ硬化剤を含有することが好ましい（請求項６）。 The present invention relates to (A) an epoxy resin, (B) a phenol resin, and (C) a vinyl containing an unsaturated carboxylic acid derivative having a functional group capable of reacting with an epoxy resin or an epoxy curing agent as a monomer component. An adhesive layer containing a copolymer and a (D) siloxane compound is laminated on an organic film (claim 1).
The (D) siloxane compound 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)
It is preferable that the organic film is a fluororesin film.
It is preferable that the fluororesin film is made of a trifluoroethylene chloride copolymer.
The adhesive layer preferably contains a coupling agent (Claim 5).
It is preferable that the adhesive layer contains an epoxy curing agent (Claim 6).

According to the present invention, the adhesive layer has (A) an epoxy resin, (B) a phenol resin, and (C) an unsaturated carboxylic acid having a functional group that can react with an epoxy resin or an epoxy curing agent as a monomer component Since it contains a vinyl copolymer containing an acid derivative and (D) a siloxane compound, it is possible to provide a back sheet having excellent adhesion to an organic film.

According to the present invention, since a fluororesin film having a low water vapor transmission rate can be used as the organic film, a back sheet having a low water vapor transmission rate can be provided.

Hereinafter, the present invention will be described with reference to the drawings, but the present invention is not limited thereto.
The back sheet 30 in the present invention is a member that protects the back side of the single-sided light-receiving solar cell, and is formed by laminating an adhesive layer 20 on the organic film 10 as shown in FIG. As long as the organic film 10 exists on the surface side (not necessarily the outermost surface) of the back sheet, the other layer configuration is not particularly limited.
Therefore, for example, a new adhesive layer may be provided on the organic film 10 on which the adhesive layer 20 is laminated, or a hard coat layer may be provided. Moreover, a new resin film may be laminated on the adhesive layer 20 on which the organic film 10 is laminated, or a transparent adhesive for sealing film may be laminated.

The adhesive strength between the organic film 10 and the adhesive layer 20 is excellent in a laminate in which the adhesive layer 20 and the organic film 10 are sequentially laminated on a polyethylene terephthalate (PET) film having a thickness of 100 μm. When 10 is peeled off from the adhesive layer 20 under a predetermined condition, the organic film 10 is torn before being peeled off.
The predetermined condition means a tensilon universal testing machine (trade name: RTC-1210A manufactured by ORIENTEC) operated by a full scale 10N.

<Adhesive layer>
The adhesive layer of the present invention comprises (A) an epoxy resin [hereinafter referred to as (A) component], (B) a phenol resin [hereinafter referred to as (B) component], and (C) ethylene and an epoxy resin as monomer components. Or a vinyl copolymer containing an unsaturated carboxylic acid derivative having a functional group capable of reacting with an epoxy curing agent [hereinafter referred to as (C) component], (D) a siloxane compound [hereinafter referred to as (D) component], It is necessary to contain.
Since the adhesive layer composed of these components is white, it cannot be used for a protective sheet that protects the surface of the solar cell, and must be used for a back sheet that protects the back side of the solar cell. It is.

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 force with the organic film tends to be insufficient. On the other hand, when the thickness exceeds 100 μm, the adhesive strength with the organic film is excellent, but when the adhesive layer is provided by coating, the adhesive layer must be formed several times, which is complicated.
Hereinafter, these components will be described sequentially.

[(A) component]
The component (A) plays a role of reacting with the component (B), the component (C), and the component (D) by heating to form a three-dimensional network configuration. Thereby, the adhesive force with respect to an organic film can be improved. The content of the component (A) in the adhesive layer of the present invention is preferably 3 to 45% by weight, more preferably 5 to 25% by weight based on the total solid content of the adhesive layer.

The epoxy resin used as the component (A) is a resin having two or more epoxy groups in the molecule. As the component (A), for example, any structure such as glycidyl ether, glycidyl ester, glycidyl amine, linear aliphatic epoxide, alicyclic epoxide can be used.

Specifically, bifunctional epoxy resins such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, naphthalene type epoxy resin, triglycidyl isocyanurate type epoxy resin, triglycidyl-p-aminophenol Type epoxy resin, tetraglycidyldiaminodiphenylmethane type epoxy resin, tetraglycidylmetaxylenediamine type epoxy resin, tetraglycidyl-1,3-bisaminomethylcyclophene type epoxy resin, etc., polyfunctional glycidylamine type epoxy resin, tetraphenylglycidyl Polyfunctional glycidyl ether type epoxy resin such as ether ethane type epoxy resin, triphenyl glycidyl ether methane type epoxy resin, phenol type epoxy resin, alkylphenol Multifunctional resol type epoxy resins such as Nord 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.
Among these, bisphenol type epoxy resins are preferably used in the present invention because they are inexpensive. In addition, the polyfunctional epoxy resin is suitably used in the present invention because of its excellent heat resistance.
Moreover, it is preferable to use a halogenated epoxy resin, particularly a brominated epoxy resin, as the component (A) because it is effective for imparting flame retardancy to the adhesive layer. Further, a phosphide epoxy resin or the like may be used instead of the halogenated epoxy resin.
These may be used alone or in combination of two or more.

The component (A) preferably has an epoxy equivalent (molecular weight per epoxy group) of 100 to 4000, more preferably 100 to 2000, and particularly preferably 100 to 1000. If the epoxy equivalent is less than 100, foaming tends to occur when cured, which may reduce the adhesive strength. When the epoxy equivalent is more than 4000, it becomes difficult to dissolve in a solvent, and compatibility with other resins is not preferable.

[Component (B)]
The phenol resin used as the component (B) is a resin obtained by addition / condensation of phenols and aldehydes, and reacts with an epoxy resin to form a three-dimensional network structure.
Examples of the component (B) include phenol derivatives such as a resole phenol resin, a phenol novolac 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.
The content of the component (B) in the adhesive layer of the present invention is preferably 2 to 30% by weight, more preferably 5 to 25% by weight based on the total solid content of the adhesive layer.

In addition, the ratio of the component (A) to the component (B) in the adhesive layer of the present invention is preferably a functional group equivalent ratio and is in the range of 1: 0.6 to 1: 1.4. : More preferably within the range of 0.7 to 1: 1.1. That is, when the content of the component (B) when the component (A) is 1 is less than 0.6, the cured adhesive layer tends to be brittle. Further, when the content of the component (B) when the component (A) is 1 is more than 1.4, the adhesive force tends to be lowered. For example, when it is used for a long period of time as an adhesive layer of a solar cell, there is a risk that the adhesive force will decrease with repeated temperature changes.
Here, the functional group equivalent ratio of the component (A) and the component (B) is the number of epoxy groups in the component (A) (the functional group of the component (A)) and the hydroxyl group in the component (B) ( (B) the ratio to the number of functional groups).

[Component (C)]
Component (C) is a vinyl copolymer containing, as a monomer component, ethylene and an unsaturated carboxylic acid derivative having a functional group capable of reacting with an epoxy resin or an epoxy curing agent. By containing the component (C), the moisture resistance is improved, and the combination with the component (A), the component (B) and the component (C) improves the adhesive force with the organic film.

The vinyl copolymer constituting the present invention contains at least ethylene and an unsaturated carboxylic acid derivative having a functional group capable of reacting with the epoxy resin or the epoxy curing agent as main monomer components. A small amount of the third 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.

Functional groups that can react with the epoxy resin or epoxy curing agent include amino groups, isocyanate groups, glycidyl groups, carboxyl groups (including anhydride groups), silanol groups, hydroxyl groups, vinyl groups, methylol groups, mercapto groups, esters. Among them, an amino group, a carboxyl group, a glycidyl group, and a hydroxyl group are preferable because of their high reactivity. Particularly preferred functional groups are glycidyl and carboxyl groups. Specific examples of the unsaturated carboxylic acid derivative having these groups include the following. Examples of those having a carboxyl group include acrylic acid, methacrylic acid, (anhydrous) maleic acid, olefins such as propylene having a carboxyl group, and those having a glycidyl group include glycidyl acrylate, glycidyl methacrylate, and the like. Examples of those containing a hydroxyl group include hydroxymethyl acrylate, hydroxymethyl methacrylate, hydroxyethyl acrylate, and hydroxyethyl methacrylate. The third monomer copolymerizable with the ethylene and the unsaturated carboxylic acid derivative having a functional group may be an alkyl (meth) acrylate such as methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, or the like. Examples include aryl esters and vinyl acetate.

In the present invention, the vinyl copolymer is preferably an ethylene- (meth) acrylic acid ester-maleic anhydride copolymer, an ethylene- (meth) acrylic acid alkyl ester-glycidyl (meth) acrylate copolymer, Examples include ethylene-glycidyl (meth) acrylate copolymer, ethylene- (meth) acrylic acid copolymer, and ethylene-glycidyl (meth) acrylate-vinyl acetate copolymer. Among these, ethylene- (meth) acrylic acid alkyl ester-maleic anhydride copolymer, 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 reduced and is not suitable for a coating solution (paint). If it exceeds 40 mol%, the cloudiness of the sealing film resin due to hydrolysis Is likely to occur.

In the component (C), the proportion of ethylene is preferably 40% by weight or more, more preferably 50 to 98% by weight, based on the total of all monomer components.
In the component (C), the content of the unsaturated carboxylic acid derivative in the vinyl copolymer 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.

In the present invention, the vinyl copolymer is contained in an amount of 20 to 200 parts by weight, preferably 50 to 150 parts by weight, based on 100 parts by weight of the total of the epoxy resin and the epoxy curing agent. When the content is more than 200 parts by weight, the film forming property tends to deteriorate. On the other hand, if the amount is less than 20 parts by weight, the film tends to be brittle.

[(D) component]
The adhesive layer of the present invention contains (D) a siloxane compound, thereby improving the compatibility of each component when the components (A) to (C) are dissolved in an organic solvent to form a coating material, and curing. There is an advantage that the moisture absorption rate of the subsequent adhesive layer can be reduced.
(D) As a component, what has the reactive group which has the reactivity with respect to an epoxy group is preferable. Examples of such a reactive group include a hydroxyl group, an alkoxy group, an amino group, a methacryl group, and an epoxy group.

The component (D) is preferably a siloxane compound having an amino group at both ends, and is particularly at least one selected from the group consisting of siloxane compounds represented by the following general formula (1) or general formula (2). It is preferable.

（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), trade names: TSL9306 (diaminodisiloxane) manufactured by Toshiba Silicone Co., Ltd., trade names: TSL9886 (diaminopoly) Siloxane), trade name: TSF4706 (diaminodisiloxane), trade name: XF42-A2645 (diaminopolysiloxane), and the like.

In the adhesive layer of the present invention, the content of the component (D) is preferably 0.05 to 10% by weight, more preferably 0.3 to 5% by weight, based on the total solid content of the adhesive layer. If it is less than 0.05% by weight, the compatibility of the components (A) to (C) when the adhesive layer of the present invention is used as a coating material is not preferable, and the moisture absorption after curing may be increased. is there. If it exceeds 10% by weight, the adhesive strength may be lowered.

[Other optional ingredients]
Moreover, in order to improve adhesiveness with EVA and an 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.

The adhesive layer of the present invention preferably contains an epoxy curing agent together with the component (A). Thereby, the curing reaction of the adhesive layer of the present invention is promoted, and the heat resistance is improved.
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.
In the adhesive layer of the present invention, the content of the epoxy curing agent is preferably 0.1 to 10% by weight, more preferably 0.1 to 3% by weight, based on the total solid content of the adhesive layer.

The adhesive layer of the present invention can be formed by applying and drying an organic film with a paint in which the components (A) to (D), which are essential components, are dissolved 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.

<Organic film>
If an organic film is a thing with a small water-vapor-permeation rate, it can be used conveniently as a solar cell backsheet. Moreover, since it is used as a back sheet, it is not necessary to use a material having excellent light transmittance. When the hard coat layer is not laminated on the organic film of the back sheet, it is preferable to use an organic film having light resistance.
In the present invention, an organic film having a low water vapor transmission rate means that the water vapor transmission rate is 1.0 × 10 ⁻⁴ g / m ² · 24 hr or less as a result of measurement according to JIS-K7126.
In the present invention, an organic film having excellent light resistance is a solar cell using the organic film as a back sheet for a solar cell in a sunshine weatherometer (manufactured by Suga Test Instruments Co., Ltd.) and light irradiation with a xenon lamp ( An accelerated weathering test that repeats rainfall for 8 minutes every 2 hours while irradiating intensity: 3 SUN, atmosphere: black panel temperature 83 ° C / humidity 50%) and showing no change in appearance after 5000 hours ( Means a substance that does not cause yellowing).

The organic film used in the present invention is not particularly limited as long as the water vapor transmission rate is 1.0 × 10 ⁻⁴ g / m ² · 24 hr, and examples thereof include a fluororesin film. Specifically, polytetrafluoroethylene (PTFE), 4-fluoroethylene-perchloroalkoxy copolymer (PFA), 4-fluoroethylene-6-fluoropropylene copolymer (FEP), 2-ethylene Examples thereof include fluororesin films such as -4-fluoroethylene copolymer (ETFE), poly-3-fluoroethylene chloride (PCTFE), polyvinylidene fluoride (PVDF), and polyvinyl fluoride (PVF). Among these, it is preferable to use PCTFE because of its low water vapor transmission rate.
Moreover, the fluororesin film is excellent in weather resistance and can be used on the outermost surface of the back sheet.

The thickness of the organic film is preferably 6 to 250 μm, more preferably 10 to 100 μm, and particularly preferably 20 to 50 μm. If it is 6 μm or less, the water vapor transmission rate may be insufficient. If it exceeds 250 μm, the water vapor transmission rate is small, but it is not preferable from the economical aspect.
EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to this at all.

The organic film surface on which the adhesive layer is laminated may be subjected to physical treatment such as corona surface treatment, flame treatment, plasma treatment or the like as a pretreatment for improving the coating property.

An adhesive layer having the following composition was dissolved in toluene to prepare a coating material (solid content 35% by weight) for forming the adhesive layer.
(A) Triphenylmethane type polyfunctional epoxy resin (Nippon Kayaku Co., Ltd., trade name: ERPPN501H) 39.8 parts by weight (B) Resol phenol resin (Showa High Polymer Co., Ltd., trade name: Shonor CKM 2400) 19 weights Part (C) ethylene-ethyl acrylate-maleic anhydride copolymer (trade name: Bondine AX8390, manufactured by Sumitomo Atchem) 40 parts by weight- (D) diaminodisiloxane (trade name: TSL9306 manufactured by Toshiba Silicone) 2 parts by weight Next, a coating composed of these components is applied onto a 23 μm thick polytrichlorofluoroethylene film (trade name: NEOFLON PCTFE manufactured by Daikin Industries, Ltd.) so that the thickness after drying is 25 μm. And it dried at 130 degreeC for 5 minute (s) in the hot air circulation type dryer, and produced the back sheet | seat.

An adhesive layer having the following composition was dissolved in toluene to prepare a coating material (solid content 35% by weight) for forming the adhesive layer.
・ (A) Tetraglycidyldiphenylmethane type epoxy resin (trade name: Epicoat 604, manufactured by Yuka Shell Co., Ltd.) 26.7 parts by weight (B) resol phenol resin (trade name: Shownol BRG 555, manufactured by Showa Polymer Co., Ltd.) 12.6 Parts by weight. (C) ethylene-glycidyl methacrylate copolymer (trade name: Bondfast E, manufactured by Sumitomo Chemical Co., Ltd.) 59 parts by weight. (D) diaminopolysiloxane (trade name: TSL9886, manufactured by Toshiba Silicone) 1.7 weight Next, a paint composed of these components was applied onto a poly (trifluorochloroethylene) film having a thickness of 50 μm (trade name: NEOFLON PCTFE manufactured by Daikin Industries, Ltd.) so that the thickness after drying was 25 μm. A back sheet was prepared by drying at 130 ° C. for 5 minutes in a hot-air circulating dryer.

An adhesive layer having the following composition was dissolved in toluene to prepare a coating material (solid content 35% by weight) for forming the adhesive layer.
-(A) Dicyclo type epoxy resin (trade name: HP-7200H, manufactured by Dainippon Ink & Chemicals, Inc.) 26.7 parts by weight-(B) Resol phenol resin (trade name: Shownol BRG555, manufactured by Showa High Polymer Co., Ltd.) 6 parts by weight. (C) ethylene-glycidyl methacrylate copolymer (trade name: Bondfast E, manufactured by Sumitomo Chemical Co., Ltd.) 59 parts by weight. (D) diaminopolysiloxane (trade name, manufactured by Toshiba Silicone Co., Ltd .: TSL 9886) 1.7 Part by weight Next, a paint composed of these components is applied onto a 75 μm-thick poly (trifluorochloroethylene) film (trade name: NEOFLON PCTFE, manufactured by Daikin Industries, Ltd.) so that the thickness after drying is 25 μm. Then, it was dried at 130 ° C. for 5 minutes in a hot air circulation dryer to prepare a back sheet.

An adhesive layer having the following composition was dissolved in toluene to prepare a coating material (solid content 35% by weight) for forming the adhesive layer.
・ (A) 40 parts by weight of dicyclo type epoxy resin (Dainippon Ink Chemical Co., Ltd., trade name: HP-7200H) ・ (B) Resol phenol resin (trade name: Shounol BRG555, manufactured by Showa Polymer Co., Ltd.) 18.6 weight Part (C) ethylene-glycidyl methacrylate copolymer (trade name: Bondfast E manufactured by Sumitomo Chemical Co., Ltd.) 33.7 parts by weight (D) diaminopolysiloxane (trade name: TSL9886 manufactured by Toshiba Silicone) 4.7 Part by weight / Amino-based silane coupling agent (trade name: Silaace S310, manufactured by Chisso) 3 parts by weight Next, a poly 3 having a thickness of 75 μm is used so that the thickness after drying the paint composed of these components becomes 25 μm. It is coated on a chlorofluoroethylene film (trade name: NEOFLON PCTFE, manufactured by Daikin Industries, Ltd.) and 1 in a hot air circulation dryer. 0 ℃ in dried 5 minutes to prepare a back sheet.

An adhesive layer having the following composition was dissolved in toluene to prepare a coating material (solid content 35% by weight) for forming the adhesive layer.
-(A) Triphenylmethane type polyfunctional epoxy resin (Nippon Kayaku Co., Ltd., trade name: ERPPN501H) 24.2 parts by weight-(B) Resol phenol resin (Showa High Polymer Co., Ltd., trade name: Shonor CKM 2400) 5 parts by weight- (C) ethylene-ethyl acrylate-maleic anhydride copolymer (trade name: Bondine AX8390, manufactured by Sumitomo Atchem) 56.5 parts by weight- (D) diaminodisiloxane (trade name, manufactured by Toshiba Silicone) TSL9306) 1.7 parts by weight / epoxy-based silane coupling agent (trade name: S510, manufactured by Chisso) 2.9 parts by weight / imidazole-based epoxy resin curing agent (trade name: Curezol C11Z, manufactured by Shikoku Chemicals) 0.19 Part by weight Next, a 75 μm-thick polysodium coating is formed so that the coating thickness of these components is 25 μm after drying. The resultant was applied onto a trichlorofluoroethylene film (trade name: NEOFLON PCTFE manufactured by Daikin Industries, Ltd.) and dried at 130 ° C. for 5 minutes in a hot-air circulating dryer to prepare a back sheet.

The following characteristics were evaluated using the backsheet produced in the examples.
[Water vapor transmission rate]
The water vapor transmission rate was measured according to JIS-K7126. The results are shown in Table 1.
[Adhesive strength]
A PET film having a thickness of 100 μm was laminated on the adhesive layer of the backsheet prepared in Examples 1 to 5, and the adhesive layer was cured by heating at 150 ° C. for 1 hour to form a laminate. Next, this laminate was set in a Tensilon universal testing machine (trade name: RTC-1210A, manufactured by ORIENTEC), and the adhesive force between the organic film constituting the back sheet and the adhesive layer was measured under the conditions of full scale 10N. When the adhesive strength between these layers was measured, the organic film was torn, and the number of adhesive strength that could be measured without tearing was shown.

As described above, Example 1 in which an adhesive layer composed of (A) component, (B) component, (C) component and (D) component was laminated on a poly (trifluorotrifluoroethylene) film which is a fluororesin film The back sheet of ˜5 had a low water vapor transmission rate and an excellent adhesion between the organic film and the adhesive layer.
Therefore, it is possible to provide a back sheet that is less likely to peel the organic film from the adhesive layer over a long period of time. In addition, it is possible to provide a back sheet having a low water vapor transmission rate and a low risk of peeling of the organic film from the adhesive layer.

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

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Organic film 20 Adhesive layer 30 Back sheet 40, 41 Transparent adhesive 50 for sealing films Solar cell element 60 Glass plate

Claims (6)

(A) an epoxy resin, (B) a phenol resin, and (C) a vinyl copolymer containing ethylene and an unsaturated carboxylic acid derivative having a functional group capable of reacting with an epoxy resin or an epoxy curing agent as a monomer component, (D) A back sheet for a solar cell, wherein an adhesive layer containing a siloxane compound is laminated on an organic film. The solar cell back according to claim 1, wherein the (D) siloxane compound is a siloxane compound having amino groups at both ends represented by the following general formula (1) or the following general formula (2). Sheet.

(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 solar cell backsheet according to claim 1, wherein the organic film is a fluororesin film. The solar cell backsheet according to claim 3, wherein the fluororesin film is made of an ethylene trifluoride chloride copolymer. The solar cell backsheet according to claim 1, wherein the adhesive layer contains a coupling agent. The solar cell backsheet according to claim 1, wherein the adhesive layer contains an epoxy curing agent.

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