JP5072339B2 - Solar cell backsheet - Google Patents

Description

  The present invention relates to a solar cell backsheet used on the back surface (opposite the light receiving surface) of a double-sided light receiving 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 has a structure in which a substrate obtained by laminating a polyethylene terephthalate (PET) film on an aluminum foil, a transparent adhesive for a sealing film, a silicon power generation element, a transparent adhesive for a sealing film, and a glass plate are sequentially laminated. Since the transparent adhesive for sealing film can be melted by heating and crosslinked and cured, the substrate, the silicon power generation element and the glass plate can be integrated by heat treatment. As a transparent adhesive for sealing films, ethylene-vinyl acetate copolymer (EVA) films are widely used.
A metal foil such as aluminum used as the substrate hardly transmits light. Therefore, the power generation amount of the solar cell depends only on sunlight transmitted through the glass plate as the light receiving surface.

The installation direction and the installation location of the single-sided light-receiving solar cell are limited. Therefore, in order to expand the use of solar cells, the development of double-sided light-receiving solar cells has been promoted, and sunlight is transmitted by using a transparent organic film instead of the substrate of single-sided light-receiving solar cells. (For example, refer to Patent Document 1). The present invention relates to a cover material for a solar cell that can protect not only the front surface but also the back surface of the solar cell, and an organic film or fluororesin containing an ultraviolet absorber for improving light resistance. The film is used. Here, when the organic film is used as a cover material (back sheet) for the back surface of a double-sided light receiving solar cell, the amount of light transmitted is reduced by the action of the ultraviolet absorber, and is not suitable as a back sheet for a double-sided light receiving solar cell. There was a problem to become.

In addition, when the fluororesin film is used as a back sheet, the adhesion between the fluororesin film and the transparent adhesive for sealing film is poor. There was a risk of the adhesive peeling off.

In addition, as in the invention described in Patent Document 1, when a fluororesin film is used for a solar cell backsheet, the sheet is exposed as the outermost surface, so that the fluororesin film having a soft surface is scratched by physical force. There was a problem that was easy to stick. Then, the invention which has abrasion resistance by forming a hard-coat layer on organic films, such as a fluororesin film and PET film, is disclosed (for example, refer patent document 2). The production method involves a process of laminating a hard coat layer by applying an ultraviolet curable resin directly on an organic film and then irradiating with an ultraviolet ray. However, in general, the adhesion between the hard coat layer formed by ultraviolet curing and the organic film is poor, and the hard coat layer may peel off from the organic film during long-term use of the solar cell.

JP 2000-174296 A Japanese Laid-Open Patent Publication No. 2003-62921

  The present invention has excellent adhesion between the organic film and the transparent adhesive for the sealing film and adhesion between the organic film and the hard coat layer by laminating easy-adhesion layers on both sides of the organic film, and transmits light. An object of the present invention is to provide a solar cell backsheet (hereinafter referred to as a backsheet) having high transparency and excellent quantity.

The present invention includes a first adhesive layer adjacent to one surface of the organic film, the second adhesive layer so as to be adjacent to the other surface of the organic film is laminated, the first adhesion layer on the is obtained by laminating a hard coat layer so as to be adjacent to, the first and the second adhesive layer contains as a main component a thermoplastic resin, the glass transition of the first and the second adhesive layer A back sheet for a solar cell for laminating a transparent adhesive for a transparent sealing film so as to be adjacent to the second easy-adhesion layer, wherein the temperature is 20 to 100 ° C. (Claim 1) ).

In the backsheet of the present invention, the peel strength between the organic film / hard coat layer of the first easy-adhesion layer is preferably 90% or more in terms of the residual rate of the organic film cut piece according to JIS-K5400. (Claim 2).

In the back sheet of the present invention, the first and second easy-adhesion layers are preferably at least one thermoplastic resin selected from polyurethane, polyester and acrylic. .

In the back sheet of the present invention, the hard coat layer is preferably formed of an ultraviolet curable resin containing silicone (claim 4).

The solar cell backsheet laminate of the present invention is formed by laminating a transparent adhesive for a transparent sealing film so as to be adjacent to the second easy-adhesion layer, followed by heating and pressure bonding ( Claim 5).

  ADVANTAGE OF THE INVENTION According to this invention, the back sheet excellent in the adhesive force of an organic film and a hard-coat layer can be provided by laminating | stacking a hard-coat layer on an organic film through a 1st easily bonding layer.

  When a solar cell is formed using the back sheet of the present invention, a transparent adhesive for a sealing film is laminated on the organic film via a second easy-adhesive layer, thereby transparent for the organic film and the sealing film. The adhesive strength with the adhesive can be strengthened.

In addition, when a solar cell is formed using a back sheet in which a water-resistant layer is laminated on the second easy-adhesion layer, a solar cell having excellent water resistance is provided by laminating on a transparent adhesive for a sealing film. can do.

  According to the present invention, since the organic film, the first and second easy-adhesion layers, the hard coat layer and the water-resistant layer do not contain an ultraviolet absorber, a back sheet having excellent light transmission and high transparency is obtained. 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 in the present invention is a member that protects the back side of the double-sided light-receiving solar cell. As shown in FIG. 1, the first easy-adhesion layer 20 and the hard coat layer 10 are provided on one side of the organic film 30. The organic layer 30 is sequentially laminated, and the second easy-adhesion layer 21 is laminated on the other surface of the organic film 30. The upper surface of the hard coat layer 10 is a surface that receives reflected light from the object.
FIG. 2 is an embodiment in which a water-resistant layer 40 is laminated adjacently on the second easy-adhesion layer 21, whereby the moisture permeability of the back sheet can be reduced.
In addition, in order to maintain the light transmission amount, the back sheet in the present invention has an ultraviolet absorber on the organic film 30, the first easy-adhesion layer 20, the hard coat layer 10, the second easy-adhesion layer 21, and the water-resistant layer 40. It is not necessary to contain.

3 and 4 are diagrams showing examples of assembling solar cells using the backsheet of the present invention.
That is, in FIG. 3, the sealing film transparent adhesive 50 is provided on the second easy-adhesion layer 21 constituting the back sheet of the present invention, and is adjacent to the silicon power generation element 60, so that the other side of the silicon power generation element 60 is provided. The transparent adhesive 51 for sealing films and the glass plate 70 are sequentially provided on the side. The sealing film transparent adhesives 50 and 51 sandwiching the silicon power generation element 60 can seal the silicon power generation element 60 by heating, and can be used as a solar cell having an integrated configuration.
On the other hand, FIG. 4 is an example of a solar cell using the back sheet shown in FIG.

The material which comprises this invention is demonstrated below.
[Organic film]
The organic film is not particularly limited as long as it has an excellent light transmission amount, specifically 90% or more. For example, polyester, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), an acrylic resin, each film, such as a polycarbonate, can be mentioned. The organic film in the present invention is preferably polyethylene terephthalate, and the thickness of the film is preferably about 6 to 250 μm.
In addition, it is not preferable to contain an ultraviolet absorber in these organic films because the amount of light transmission decreases.

Since an easy-adhesion layer is provided on the surface of the organic film, it is preferable to subject the surface to physical treatment such as corona surface treatment, flame treatment, or plasma treatment as a pretreatment for improving the coating property.

[Easily adhesive layer]
Below, a 1st easily bonding layer and a 2nd easily bonding layer are demonstrated.
A 1st easily bonding layer means the thing with the excellent adhesiveness of an organic film and a hard-coat layer. Specifically, after sticking the organic film and the hard coat layer by heating through the easy-adhesion layer, the residual rate of the organic film cut piece in the cross-cut peel test according to JIS-K5400 is 90% or more. It means something.
A 2nd easily bonding layer means the thing excellent in the adhesiveness of an organic film and the transparent adhesive for sealing films (EVA). Specifically, after the organic film and the transparent adhesive for sealing film are attached by heating through the easy-adhesion layer, before peeling these components in a peeling test according to JIS-K7127. In addition, it means an adhesive having such an extent that the organic film is broken.
It is preferable that the first easy-adhesion layer and the second easy-adhesion layer contain a thermoplastic resin such as polyurethane, polyester, or acrylic as a main component. These have only to have tackiness at normal temperature and have tackiness at the time of heating. Therefore, the glass transition point is preferably in the range of 20 to 100 ° C, more preferably 30 to 80 ° C. When the glass transition point is less than 20 ° C., the easy-adhesion layer tends to have tackiness at room temperature, and may adhere when the easy-adhesion layer and the easy-adhesion layer are overlapped. It will cause problems. If the temperature exceeds 100 ° C., the adhesion with the organic film, the hard coat layer, the transparent adhesive for sealing film and the water-resistant layer may be reduced, or the easy-adhesion layer may become brittle and the adhesion may not be maintained. . Moreover, the same thing may be used for a 1st easily bonding layer and a 2nd easily bonding layer, and a different thing may be used. In addition, the glass transition temperature here means what is based on the measurement by a differential scanning calorimeter (DSC).

(Polyurethane resin)
The polyurethane resin used for the coating layer of the laminated thermoplastic resin film of the present invention is not particularly limited, but as an example, it is a resin containing a block-type isocyanate group, and the terminal isocyanate group is blocked with a hydrophilic group (hereinafter referred to as “polyisocyanate”). And heat-reacting water-soluble urethane. Examples of the blocking agent for blocking the isocyanate group with a hydrophilic group include phenols, alcohols, lactams, oximes and active methylene compounds containing bisulfites and sulfonic acid groups. The blocked isocyanate group makes the urethane prepolymer hydrophilic or water-soluble. When thermal energy is applied to the polyurethane resin during the drying or heat setting process during film production, the blocking agent deviates from the isocyanate group, so the polyurethane resin is a water-dispersible copolyester mixed with a self-crosslinked stitch. While immobilizing the resin, it also reacts with the end groups of the copolymerized polyester resin. The resin during the preparation of the coating solution is poor in water resistance because it is hydrophilic. However, when the thermal reaction is completed by coating, drying, and heat setting, the hydrophilic group of the urethane resin, that is, the blocking agent is released, so that the water resistance is low. A good coating film is obtained. Among the above blocking agents, bisulfites are most preferable from the viewpoint that the blocking agent is removed from the isocyanate group at the heat treatment temperature and heat treatment time in the film production process, and from the viewpoint of being industrially available.

The chemical composition of the urethane prepolymer used in the resin includes (1) an organic polyisocyanate having two or more active hydrogen atoms in the molecule, or a molecular weight having at least two active hydrogen atoms in the molecule. 200 to 20,000 compounds, (2) an organic polyisocyanate having two or more isocyanate groups in the molecule, or (3) a chain extender having at least two active hydrogen atoms in the molecule. The resulting compound has a terminal isocyanate group.

The compound (1) generally known is a compound containing two or more hydroxyl groups, carboxyl groups, amino groups or mercapto groups in the terminal or molecule, and particularly preferred compounds include polyether polyols. , Polyester polyol, polyether ester polyol and the like. Examples of the polyether polyol include compounds obtained by polymerizing alkylene oxides such as ethylene oxide and propylene oxide, styrene oxide, epichlorohydrin, and the like, compounds obtained by random copolymerization or block copolymerization of two or more thereof, or polyhydric alcohols thereof. There are compounds obtained by performing addition polymerization.

(Polyester resin)
The polyester resin having a glass transition point in the range of 20 to 100 ° C. is formed from the following polybasic acid or an ester-forming derivative thereof and a polyol or an ester-forming derivative thereof. That is, as the polybasic acid component, terephthalic acid, isophthalic acid, phthalic acid, phthalic anhydride, 2,6-naphthalenedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, adipic acid, sebacic acid, trimellitic acid, pyromellitic acid , Dimer acid, 5-sodium sulfoisophthalic acid and the like. A copolymer polyester resin is synthesized using preferably two or more of these acid components. Further, if it is a slight amount, an unsaturated polybasic acid component such as maleic acid, itaconic acid, or hydroxycarboxylic acid such as p-hydroxybenzoic acid can be used in combination. The polyol component includes ethylene glycol, 1,4-butanediol, diethylene glycol, dipropylene glycol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, xylene glycol, dimethylolpropane, and poly (ethylene oxide) glycol. , Poly (tetramethylene oxide) glycol and the like.

(Acrylic resin)
Examples of the acrylic resin having a glass transition point in the range of 20 to 100 ° C. include acrylic resins obtained by polymerizing acrylic monomers as exemplified below. Examples of the acrylic monomer include alkyl acrylate and alkyl methacrylate (the alkyl group includes methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl group, 2-ethylhexyl group, cyclohexyl group). Groups); hydroxyl group-containing monomers such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate and 2-hydroxypropyl methacrylate; epoxy group-containing monomers such as glycidyl acrylate, glycidyl methacrylate and allyl glycidyl ether; Acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, styrene sulfonic acid and its salts (sodium salt, potassium salt, ammonium salt, tertiary amine salt, etc.) A monomer containing a carboxy group, a sulfoxy group or a salt thereof; acrylamide, methacrylamide, N-alkylacrylamide, N-alkylmethacrylamide, N, N-dialkylacrylamide, N, N-dialkylmethacrylamide (as alkyl groups, Methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl group, 2-ethylhexyl group, cyclohexyl group, etc.), N-alkoxyacrylamide, N-alkoxymethacrylamide, N, N-dialkoxyacrylamide, N, N-dialkoxymethacrylamide (alkoxy groups include methoxy, ethoxy, butoxy, isobutoxy, etc.), acryloylmorpholine, N-methylolacrylamide, N-methylol Monomers containing amide groups such as clinamide, N-phenylacrylamide, N-phenylmethacrylamide; monomers of acid anhydrides such as maleic anhydride and itaconic anhydride; vinyl isocyanate, allyl isocyanate, styrene, α-methylstyrene, vinyl Methyl ether, vinyl ethyl ether, vinyl trialkoxysilane, alkylmaleic acid monoester, alkyl fumaric acid monoester, alkylitaconic acid monoester, acrylonitrile, methacrylonitrile, vinylidene chloride, ethylene, propylene, vinyl chloride, vinyl acetate, butadiene And the like.

Among these, monomers containing a hydroxyl group such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, N-methylol acrylamide, N-methylol methacrylamide and the like are 2-20. It is preferably contained in a mol%, preferably 4 to 15 mol%.

  The easy-adhesion layer in the present invention can contain a crosslinking agent, a wax, an antistatic agent, a colorant, a surfactant and the like as appropriate, but the inclusion of an ultraviolet absorber reduces the amount of light transmitted. Is not preferable.

The 1st and 2nd easily-adhesive layer which comprises this invention should just exist on both surfaces of an organic film, The application | coating method can be suitably selected from the following. Examples thereof include a roll coating method, a gravure coating method, a roll brush method, a spray coating method, an air knife coating method, an impregnation method, and a curtain coating method. These methods may be used alone or in combination.

It is preferable that the thickness of an easily bonding layer is 0.01-1 micrometer. If it is less than 0.01 μm, the adhesive force between the organic film and the hard coat layer, the organic film and the transparent adhesive for sealing film, and the organic film and the water-resistant layer may be insufficient. If it exceeds 1 μm, Newton rings may be easily generated, and the light transmittance may be reduced.

[Hard coat layer]
The hard coat layer referred to in the present invention is preferably formed of an ultraviolet curable resin.
Although a well-known thing can be used for an ultraviolet curable resin, generally it is comprised from a polyfunctional monomer, a monofunctional monomer, a polymerizable oligomer, a photoinitiator, and an additive. Further, silicone can be contained in the ultraviolet curable resin.

Examples of the multifunctional monomer include pentaerythritol triacrylate, pentaerythritol tetraacrylate, pentaerythritol tetramethacrylate, dipentaerythritol triacrylate, dipentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, and the like. Can be used.

Monofunctional monomers include, for example, acrylic acid, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, isobutyl acrylate, t-butyl acrylate, isooctyl acrylate, lauryl acrylate, stearyl acrylate, isovol Nyl acrylate, cyclohexyl acrylate, 2-methoxyethyl acrylate, methoxytriethylene glycol acrylate, 2-ethoxyethyl acrylate, tetrahydrofurfuryl acrylate, benzyl acrylate, ethyl carbitol acrylate, phenoxyethyl acrylate, and the like can be used.

As the polymerizable oligomer, for example, an oligomer such as a urethane oligomer, a polyester oligomer or an epoxy oligomer having a plurality of ethylenic double bonds (preferably an acryloyl group or a methacryloyl group) can be used.

Examples of the photopolymerization initiator include benzoin, benzophenone, benzoyl methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, dibenzyl, 5-nitroacenaphthene, hexachlorocyclopentadiene, p-nitrodiphenyl, p-nitroaniline. 2,4,6-trinitroaniline, 1,2-benzanthraquinone, 3-methyl-1,3-diaza-1,9-benzanthrone; acetophenone, acetophenone benzyl ketal, anthraquinone, 1-hydroxycyclohexyl phenyl ketone, 2,2-dimethoxy-2-phenylacetophenone, xanthone compounds, triphenylamine, carbazole, 3-methylacetophenone, 4-chlorobenzophenone, 4,4'- Methoxybenzophenone, 4,4′-diaminobenzophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, Carbazole, xanthone, 1,1-dimethoxydeoxybenzoin, 3,3′-dimethyl-4-methoxybenzophenone, thioxanthone compound, diethylthioxanthone, 2-isopropylthioxanthone, 2-chlorothioxanthone, 1- (4-dodecylphenyl)- 2-hydroxy-2-methylpropan-1-one, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-propan-1-one, triphenylamine, 2,4,6-trimethylbenzoyl Diphenylphosphine oxide, bis- (2,6- Dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, bisacylphosphine oxide, benzyldimethyl ketal, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, Fluorenone, fluorene, benzaldehyde, Michler's ketone, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butan-1-one, 3-methylacetophenone, 3,3 ′, 4,4′-tetra ( and t-butylperoxycarbonyl) benzophenone (BTTB). Of these, benzophenone and 1-hydroxycyclohexyl phenyl ketone are particularly preferable.

The polyfunctional monomer, monofunctional monomer, polymerizable oligomer, and photopolymerization initiator may be used alone or in combination of two or more.
Moreover, 1 type of polymerizable oligomer, a polyfunctional monomer, a monofunctional monomer, and a photoinitiator may each be used, and may be used in combination of 2 or more type.

As an additive, if the light transmittance of the hard coat layer containing the additive is 90% or more, it can be added as necessary. Specific examples include colorants, inorganic fillers, organic fillers, and the like.

Since the hard coat layer containing silicone in the ultraviolet curable resin has improved water repellency and slipperiness, it is difficult for dirt to adhere to the surface of the hard coat layer. The amount of silicone added is preferably 0.01 to 0.1 parts by weight with respect to 100 parts by weight of the resin component. If it is less than 0.01 part by weight, water repellency and slipperiness may be insufficient, and if it exceeds 0.1 part by weight, flexibility may increase and surface hardness may decrease.

[Water resistant layer]
The water-resistant layer described in FIG. 2 is provided to improve moisture permeability, and has excellent adhesion with the transparent adhesive for sealing film on the silicon power generation element. In order to improve the adhesive force between the easy adhesion layer and the transparent adhesive for sealing film, it is preferable to use an ultraviolet curable resin as the water resistant layer, and an ultraviolet curable acrylic resin, an acrylic silicon resin, or the like is preferably used. Can be used.
Here, the adhesive having excellent adhesive force with the transparent adhesive means that the constituent itself is not peeled off from the transparent adhesive for sealing film and the water-resistant layer by the measurement method according to JIS-K7127. The one that is torn.
Hereinafter, the present invention will be described by way of examples.

[Example 1]
In a 100 μm-thick PET film (trade name: Cosmo Shine A4100, manufactured by Toyobo Co., Ltd., having an easy-adhesion layer only on one side) having a first easy-adhesion layer made of a polyester resin having a glass transition temperature of about 70 ° C. A silicone-containing ultraviolet ray comprising 100 parts by weight of dipentaerythritol hexaacrylate, 2 parts by weight of a photopolymerization initiator (product name: Irgacure 184, manufactured by Ciba Specialty Chemicals), and 1 part by weight of a silicone-based surfactant. A curable acrylic was applied. Subsequently, an 80 W / cm high-pressure mercury lamp was irradiated for 4 seconds from a distance of 12 cm to be cured to form a hard coat layer. A sample for evaluating the backsheet was prepared by heating at about 130 ° C. In addition, the thickness of the silicone-containing ultraviolet curable acrylic after curing was 3 μm.

[Reference Example 2]
A sample for evaluating the backsheet of the present invention was prepared in the same manner as in Example 1 except that the thickness of the cured silicone-containing ultraviolet curable acrylic was 6 μm.

[Example 3]
100 μm-thick PET film having first and second easy-adhesion layers made of polyester resin having a glass transition temperature of about 70 ° C. (trade name: Cosmo Shine A4300, manufactured by Toyobo Co., Ltd., with easy-adhesion layers formed on both sides) A back sheet was produced in the same manner as in Example 1 except that was used. Subsequently, an EVA sheet (trade name Solar EVA SC4 manufactured by Mitsui Chemicals Fabro Co., Ltd.) was stacked as a transparent adhesive for the sealing film on the second easy-adhesion layer and pre-pressed at a temperature of 80 ° C. A glass sheet was overlaid on the EVA sheet, and a back sheet laminate was produced by heat and pressure bonding with a vacuum laminator at 150 ° C., a vacuum of 3 minutes, a pressure of 8 minutes, and a press pressure of 0.5 to 1 atm according to a conventional method.

[Example 4]
Example 1 except that a 100 μm-thick PET film (trade name: Cosmo Shine A4300 manufactured by Toyobo Co., Ltd.) having first and second easy-adhesion layers made of a polyester resin having a glass transition temperature of about 70 ° C. was used. Similarly, a back sheet was produced. Subsequently, a backsheet laminate was produced in the same manner as in Example 3 except that a water-resistant layer made of an ultraviolet curable resin was applied on the second easy-adhesion layer and cured by ultraviolet irradiation.

[Comparative Example 1]
A 100 μm thick PET film (trade name: Tetron HB, manufactured by Teijin DuPont Films Ltd.) was used to form a hard coat layer in the same manner as in Example 1 except that the first easy-adhesion layer was not provided.

[Comparative Example 2]
In the back sheet of Example 1, the EVA sheet was directly laminated on the PET not provided with the second easy-adhesion layer, and pre-pressed at a temperature of 80 ° C. A glass sheet was overlaid on the EVA sheet, and a back sheet laminate was produced by heat and pressure bonding with a vacuum laminator at 150 ° C., a vacuum of 3 minutes, a pressure of 8 minutes, and a press pressure of 0.5 to 1 atm according to a conventional method.

[Comparative Example 3]
A backsheet laminate was produced in the same manner as in Comparative Example 2 except that the backsheet of Example 1 was subjected to corona treatment on PET without the second easy adhesion layer.

[Reference Example 1]
A backsheet laminate was produced in the same manner as in Example 3 except that 2 parts by weight of the ultraviolet absorber was added.

(Evaluation)
In order to measure the adhesion between the organic film and the hard coat layer in the backsheets produced in Example 1, Reference Example 2 and Comparative Example 1, a cross-cut peel test was performed according to JIS-K5400. When the remaining rate of the organic film cut piece was 90% or more, ○, 100% were evaluated as ◎, and less than 90% were evaluated as ×.

  In the backsheet laminates produced in Examples 3 and 4, Comparative Examples 2 and 3, and Reference Example 1, the adhesive strength with the sealing film transparent adhesive was evaluated according to JIS-K7127. About 24 hours after bonding, a 180 ° peel test was performed between the EVA sheet and the back sheet using a tensile tester under a tensile condition of 300 mm / min. Although the adhesive strength represents N / cm, the case where the PET film was torn during the peeling process was marked as ◯.

The total light transmittance was measured according to JIS-K7105.
The surface hardness was measured according to JIS-K5401, and the hardness (pencil strength) in the hard coat layer was shown.
In the wear resistance, in the steel wool abrasion test (load 250 g / cm) on the hard coat layer, the case where no scratches were observed by visual observation was evaluated as ◯, and the case where the scratches were observed was evaluated as x.
The haze value was measured according to JIS-K7105, and less than 1% was marked with ◯, and 1% or more was marked with x.
The moisture permeability was measured according to JIS-K7126, and less than 2.0 g / m 2 · day was indicated by “◯” and 2.0 g / m 2 · day or more was indicated by “X”.

Moreover, the Example structure did the ultraviolet-ray carbon arc test according to JIS-B7753. The total light transmittance after irradiation with ultraviolet rays for 500 hours was measured according to JIS-K7105.
The above results are summarized in Table 1.

The adhesive force with the hard coat layer showed good results in Example 1 and Reference Example 2 in which the hard coat layer was provided on the first easy-adhesion layer. On the other hand, the adhesive force with the hard coat layer of Comparative Example 1 in which the hard coat layer was laminated on the organic film without providing the first easy-adhesion layer was insufficient.

  The adhesive strength with the EVA sheet shows good results in Example 3 in which the EVA sheet is provided on the second easy-adhesive layer and Example 4 in which the water-resistant layer and the EVA sheet are sequentially provided on the second easy-adhesive layer. Indicated. On the other hand, the adhesive strength between the EVA sheet of Comparative Example 2 in which the EVA sheet was directly laminated on the organic film and the corona treatment on the organic film without providing the second easy-adhesion layer was insufficient. It was.

  Moreover, the total light transmittance of the reference example 1 which made the hard-coat layer contain the ultraviolet absorber was inferior compared with the Example and comparative example which did not contain the ultraviolet absorber.

  The configuration of the example and the comparative example were excellent in surface hardness and wear resistance because the hard coat layer was provided on the outermost surface. Moreover, in any structure, since the hard coat layer contains silicone, the moisture permeability was small.

  The total light transmittance after irradiation with ultraviolet rays for 500 hours was 90% or more in any of the constructions of the examples, and it had light resistance even without containing an ultraviolet absorber.

As mentioned above, the Example structure which provided the easily bonding layer of this invention on both surfaces of the organic film from Table 1 has maintained the total light transmittance and the cloudiness suitably, and was difficult with the prior art hard coat layer and Adhesiveness with the transparent adhesive for sealing films (EVA sheet) was able to be improved.

  According to the present invention, there is provided a back sheet having excellent transparency between an organic film and a transparent adhesive for a sealing film and an adhesion between an organic film and a hard coat layer, and a high transparency with an excellent light transmission amount. be able to.

It is sectional drawing which shows embodiment of the solar cell backsheet of this invention. It is sectional drawing which shows another embodiment of the solar cell backsheet of this invention. It is sectional drawing of the solar cell which uses the solar cell backsheet of FIG. It is sectional drawing of the solar cell which uses the solar cell backsheet of FIG.

DESCRIPTION OF SYMBOLS 10 Hard-coat layer 20 1st easily bonding layer 21 2nd easily bonding layer 30 Organic film 40 Water resistant layers 50 and 51 Transparent adhesive 60 for sealing films Silicon power generation element 70 Glass plate

Claims (5)

The first adhesive layer adjacent to one surface of the organic film, the second adhesive layer so as to be adjacent to the other surface of the organic film are laminated, so that adjacent to the first adhesion layer on the The first and second easy-adhesion layers contain a thermoplastic resin as a main component, and the glass transition temperature of the first and second easy-adhesion layers is from 20 to The solar cell backsheet for laminating | stacking the transparent adhesive for transparent sealing films so that it may adjoin on the said 2nd easily bonding layer characterized by being 100 degreeC .   2. The sun according to claim 1, wherein the peel strength between the organic film / hard coat layer of the first easy-adhesion layer is 90% or more in terms of the residual rate of the organic film cut piece according to JIS-K5400. Battery backsheet.   3. The solar cell back according to claim 1, wherein the first and second easy-adhesion layers are at least one thermoplastic resin selected from polyurethane, polyester and acrylic. 4. Sheet.   The solar cell backsheet according to any one of claims 1 to 3, wherein the hard coat layer is formed of an ultraviolet curable resin containing silicone.   A transparent adhesive for a transparent sealing film is laminated so as to be adjacent to the second easy-adhesion layer according to any one of claims 1 to 4, and is heated and pressed under pressure. Battery backsheet laminate.

Images