JP2010021167A - Solar cell back sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solar cell back sheet having transparency, moisture prevention performance, decoration performance and light scattering performance. <P>SOLUTION: The solar cell back sheet 1 has a structure in which a colored layer 12 of ≥10 nm and ≤1 μm is formed between at least two or more white resin films 10, a metal oxide layer 16 is preferably formed on the colored layer 12, and a coating film 18 containing metal alkoxide expressed by (R<SP>1</SP>)<SB>m</SB>-M<SP>1</SP>-(OR<SP>2</SP>)<SB>4-m</SB>(wherein R<SP>1</SP>and R<SP>2</SP>denote independently organic group of 1-8C, M<SP>1</SP>denotes Si, Zr or Ti, respectively), or expressed by Al-(OR<SP>3</SP>)<SB>3</SB>(wherein R<SP>3</SP>denotes an organic group of 1-8C) as a material is more preferably formed on an upper layer of the metal oxide layer 16. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a solar battery back sheet which is a member constituting a solar battery module.

  Solar cells have been put into practical use as a new energy source that is pollution-free and friendly to the global environment. Crystalline silicon solar cells are widely used in general households, and thin silicon silicon solar cells are backed by the shortage of silicon as a raw material. Technology is also progressing rapidly.

  When a solar cell is used in a configuration integrated with a roof member, a plurality of solar cell elements are combined, and the element group is protected by a cover material having a predetermined function on the front and back surfaces of the element group. It is common to use as a module.

  The cover material on the light receiving surface side of the solar cell element uses a transparent glass substrate, and the back side cover material (hereinafter referred to as a solar cell back sheet) uses, for example, a back sheet made of a highly weather resistant resin film. . And the method of sealing between that with an EVA (ethylene vinyl acetate copolymer) film is taken.

The backsheet needs to be moisture-proof because the solar cell element is vulnerable to moisture, which can be improved by using a metal foil, but if the metal foil is used, the withstand voltage is lowered, and However, it is not suitable for a see-through solar cell because of low transparency. Therefore, for example, Patent Document 1 proposes a back sheet excellent in moisture resistance using a hydrolysis-resistant white resin film.
This method can certainly provide a back sheet having excellent moisture resistance and transparency, but it can only be translucent white as a color, and is not particularly decorative as a see-through solar cell. If the white resin film is changed to a film having a color, the film is thick, so that the color becomes dark, the transparency is deteriorated, and the cost of the coloring material is increased.
Japanese Patent Laid-Open No. 2002-100788

  In view of the problems as described above, an object of the present invention is to provide a solar cell backsheet having transparency, moisture resistance, decorativeness, and light scattering.

The invention described in claim 1 is a solar battery back sheet, wherein a colored layer of 10 nm or more and 1 μm or less is provided between at least two or more white resin films.
The invention according to claim 2 is the solar battery backsheet according to claim 1, wherein a metal oxide layer is provided on the colored layer.
The invention according to claim 3 is characterized in that the metal oxide layer is formed by a film forming method by physical vapor deposition or chemical vapor deposition and has a thickness of 5 to 1000 nm. It is a solar cell backsheet as described in.
The invention according to claim 4 is the solar cell backsheet according to claim 2 or 3, wherein a coating film using a metal alkoxide as a raw material is further provided on the metal oxide layer.
According to a fifth aspect of the present invention, in the metal alkoxide, (R ¹ ) _m -M ^1- (OR ² ) _4-m (wherein R ¹ and R ² are each independently an organic group having 1 to 8 carbon atoms). And M ¹ represents Si, Zr or Ti). The solar cell backsheet according to claim 4, wherein
The invention according to claim 6 is characterized in that the metal alkoxide is represented by Al- (OR ³ ) ₃ (wherein R ³ represents an organic group having 1 to 8 carbon atoms). It is a solar cell backsheet of description.

  According to the present invention, it is possible to provide a solar battery back sheet having moisture resistance, transparency, decoration, and light scattering properties by providing a colored layer of 10 nm to 1 μm between at least two white resin films. it can. In particular, the color can be freely changed by providing a colored layer.

  This invention is a solar cell backsheet characterized by providing a colored layer of 10 nm or more and 1 μm or less between at least two white resin films. 1-3 is sectional drawing of embodiment of the solar cell backsheet of this invention. The solar cell backsheet 1 of FIG. 1 has a configuration in which a colored layer 12 and an adhesive layer 14 are sequentially provided between two white resin films 10. The solar cell backsheet 1 of FIG. 2 has a configuration in which a colored layer 12, a metal oxide layer 16, and an adhesive layer 14 are sequentially provided between two white resin films 10. The solar cell backsheet 1 of FIG. 3 is configured such that a colored layer 12, a metal oxide layer 16, a coating film 18 using a metal alkoxide as a raw material, and an adhesive layer 14 are sequentially provided between two white resin films 10. It is.

  Examples of the film used in the present invention include polytetrafluoroethylene (PTFE), 4-fluoroethylene-perchloroalkoxy copolymer (PFA), and 4-fluoroethylene-6-fluoropropylene copolymer (FEP). , Fluoroethylene resin film such as 2-ethylene-4-fluoroethylene copolymer, polyvinylidene fluoride (PVDF), or norbornene, polycarbonate, polymethyl methacrylate, polyacrylate, polyethylene terephthalate (PET), polyethylene naphthalate (PEN) Etc. Among these, PET and PEN are desirable in consideration of productivity, cost, and the like. These films may contain additives such as an antistatic agent, an ultraviolet absorber, a plasticizer, and a slipping agent as necessary. Further, the surface may be modified such as corona treatment, flame treatment, plasma treatment, and easy adhesion treatment.

  The white resin film used in the present invention needs to have a high reflectance so as to be white in order to improve conversion efficiency as a solar cell, and is produced by adding a white pigment to the film. The film preferably has a whiteness of 80% or more and a film thickness of 6 to 300 μm (more preferably 12 to 200 μm). As the white pigment, titanium oxide or zinc oxide having a particle size of 1 μm or more and 500 μm or less is preferably used.

  The film thickness of the colored layer is 10 nm or more and 1 μm or less as described above. When the film thickness is less than 10 nm, good colors cannot be obtained. If the film thickness exceeds 1 μm, the pigment cost increases, which is not preferable. A more preferable film thickness is 30 nm or more and 300 nm or less.

  As the colored layer used in the present invention, a material obtained by adding an organic pigment or an inorganic pigment to an organic binder can be used. As the organic pigment, azo, quinone, triarylmethane, cyanine, phthalocyanine, indigo, coumarin, styryl and the like can be used. Inorganic pigments include zinc chromate, a mixture of titanium oxide, nickel and antimony, zinc chromate and lead molybdate, iron oxide, alumina-silica-sulfur mixture, manganese organic complex, ruthenium organic complex, etc. A plurality of the above pigments may be mixed.

  Examples of the organic binder include acrylic resin, epoxy resin, urethane resin, vinylidene chloride resin, acrylic / styrene copolymer resin, polyester resin, vinyl alcohol resin, ethylene vinyl alcohol resin, and silicon resin. The curing method is not particularly limited, but a thermosetting method or an ultraviolet curing method is particularly desirable.

  These resins can be dissolved in a solvent and the solid content can be adjusted to 1 to 80% by weight, more preferably 1 to 30% by weight, and coated on a substrate.

  An additive may be added to the colored layer for the purpose of preventing blocking, imparting hardness, imparting antistatic performance, or improving leveling properties. Moreover, you may add a photoinitiator, an isocyanate hardening agent, etc. by a hardening system.

  Moreover, as a formation method of a colored layer, a wet coating may be sufficient and a well-known method can be used. Specific examples include a gravure coater, a dip coater, a reverse coater, a wire bar coater, and a die coater.

  In the present invention, further high moisture resistance can be obtained by providing a metal oxide layer as a gas barrier layer on the colored layer. For this purpose, the metal oxide layer is preferably formed by vacuum film formation. As the method, physical vapor deposition or chemical vapor deposition, for example, resistance heating vacuum deposition, EB (Electron Beam) heating vacuum is used. Examples include vapor deposition, induction heating vacuum deposition, sputtering, reactive sputtering, dual magnetron sputtering, and plasma enhanced chemical vapor deposition (PECVD). Plasma is used in the items after the above sputtering, but plasma generation such as DC (Direct Current) method, RF (Radio Frequency) method, MF (Middle Frequency) method, DC pulse method, RF pulse method, DC + RF superposition method, etc. Although there is a law, it is not particularly limited.

For the metal oxide layer, aluminum oxide, silicon oxide, indium and tin composite oxide, indium and cerium composite oxide, tin, tin and titanium, or indium and cerium composite oxide containing titanium are preferable. Aluminum oxide and silicon oxide films are more preferable because they are superior to other metal oxides in terms of transparency and gas barrier properties.
The thickness of the metal oxide layer is preferably 5 nm or more and 1000 nm or less. When the film thickness is less than 5 nm, good barrier properties cannot be exhibited. On the other hand, if the film thickness exceeds 1000 nm, film cracking is likely to occur, which is not preferable.

Moreover, in this invention, it is preferable to provide the coating film which uses a metal alkoxide as a raw material on the upper layer of a metal oxide layer from the reason of contact | adherence with a metal oxide layer.
As the metal alkoxide, (R ¹ ) _m -M ^1- (OR ² ) _4-m (where R ¹ and R ² each independently represents an organic group having 1 to 8 carbon atoms, M ¹ represents Si, Zr or an Ti) or Al- ^(oR ₃₎ 3 (provided that ^{R 3} of the compound represented by the representative) an organic group having 1 to 8 carbon atoms are preferred.

As the metal alkoxide metal M ¹ is Si, tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, methyltrimethoxysilane, methyltriethoxysilane, dimethyldimethoxysilane, it is mentioned dimethyl diethoxy silane Can do.

As the metal alkoxide metal M ¹ is Zr, tetramethoxy zirconium, tetraethoxy zirconium, tetra-iso-propoxy zirconium, it may be mentioned tetrabutoxy zirconium.

As the metal alkoxide metal M ¹ is Ti, it may be mentioned tetramethoxysilane titanium, tetraethoxy titanium, tetraisopropoxy titanium, tetrabutoxy titanium and the like.

  Examples of the metal alkoxide in which the metal is Al include trimethoxyaluminum, triethoxyaluminum, triisopropoxyaluminum, and tributoxyaluminum.

  The metal alkoxide may be used alone or in combination of two or more. Further, polyvinyl alcohol or the like may be mixed.

  In order to bond two or more white resin films, it is desirable to employ an adhesive layer made of an adhesive. The adhesive is not particularly limited except that it is transparent. Generally, a method of curing a urethane adhesive with an isocyanate curing agent is used.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. The performance of the solar cell backsheet was evaluated according to the following method.
Haze: Measurement was performed according to JIS-K7105 using NDH-2000 manufactured by Nippon Denshoku.
Water vapor permeability: Measured according to JIS-Z0208.

Example 1
Using a white PET film E28G (product of Toray, whiteness: 93%) with a thickness of 100 μm, a coloring material obtained by mixing an indigo dye with acrylic polyol and isocyanate is formed to a thickness of 0.1 μm by a bar coating method. It was processed with. Thereafter, a 50 nm SiOx layer was formed by vacuum evaporation. An upper layer of urethane adhesive was processed to a thickness of 4 μm by the bar coating method, and a white PET film E28G having a thickness of 100 μm was bonded thereto. The color of this film was blue and the haze was 80%. The water vapor transmission rate was 0.5 g / m ² · day.

Example 2
Using a white PET film E28G (product of Toray, whiteness: 93%) with a thickness of 100 μm, a coloring material obtained by mixing an indigo dye with acrylic polyol and isocyanate is formed to a thickness of 0.1 μm by a bar coating method. It was processed with. A urethane adhesive was processed to a thickness of 4 μm by a bar coating method on the upper layer, and a 100 μm white PET film E28G was bonded thereto. The color of this film was blue and the haze was 80%. The water vapor transmission rate was 3 g / m ² · day.

Example 3
Using a white PET film E28G (product of Toray, whiteness: 93%) with a thickness of 100 μm, a coloring material obtained by mixing an indigo dye with acrylic polyol and isocyanate is formed to a thickness of 0.1 μm by a bar coating method. It was processed with. Thereafter, a 50 nm SiOx layer was formed by vacuum evaporation. A film obtained by hydrolysis of tetraethoxysilane is processed as an overcoat on the upper layer to a film thickness of 0.3 μm, and then a urethane adhesive is processed to a thickness of 4 μm by a bar coating method to obtain a 100 μm white PET film E28G Were pasted together. The color of this film was blue and the haze was 80%. The water vapor transmission rate was 0.1 g / m ² · day.

Comparative Example 1
Using a transparent PET film A4300 (manufactured by Toyobo Co., Ltd.) having a thickness of 100 μm, a color material obtained by mixing an indigo dye with acrylic polyol and isocyanate was processed to a thickness of 0.1 μm by a bar coating method. Thereafter, a 50 nm SiOx layer was formed by vacuum evaporation. A urethane adhesive was processed to a thickness of 4 μm by the bar coating method on the upper layer, and a 100 μm transparent PET film A4300 (manufactured by Toyobo) was bonded thereto. The color of this film was blue and the haze was 1%. The water vapor transmission rate was 0.5 g / m ² · day.

Comparative Example 2
A transparent PET film A4300 (manufactured by Toyobo Co., Ltd.) having a thickness of 100 μm was used, and a color material obtained by mixing acrylic polyol and isocyanate was processed to a thickness of 0.1 μm by the bar coating method. Thereafter, a 50 nm SiOx layer was formed by vacuum evaporation. A urethane adhesive was processed to a thickness of 4 μm by the bar coating method on the upper layer, and a 100 μm transparent PET film A4300 (manufactured by Toyobo) was bonded thereto. The color of this film was transparent and the haze was 1%. The water vapor transmission rate was 0.5 g / m ² · day.

[Table 1]

  As described above, in the present invention, a colored layer can be provided on the white resin film to impart a high-quality blue tint, and the durability of the solar cell element is enhanced by a high water vapor barrier property, and the haze is also high. Therefore, it is possible to provide a solar battery back sheet that is expected to improve the conversion efficiency due to the light scattering effect.

It is sectional drawing of embodiment of the solar cell backsheet of this invention. It is sectional drawing of embodiment of the solar cell backsheet of this invention. It is sectional drawing of embodiment of the solar cell backsheet of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 White resin film 12 Colored layer 14 Adhesion layer 16 Metal oxide layer 18 Coating film which uses metal alkoxide as raw material

Claims (6)

  A solar battery backsheet, wherein a colored layer having a thickness of 10 nm to 1 μm is provided between at least two white resin films.   The solar cell backsheet according to claim 1, wherein a metal oxide layer is provided on the colored layer.   3. The solar cell backsheet according to claim 2, wherein the metal oxide layer is formed by a film forming method using a physical vapor deposition method or a chemical vapor deposition method, and has a film thickness of 5 to 1000 nm.   The solar cell backsheet according to claim 2 or 3, wherein a coating film using a metal alkoxide as a raw material is further provided on an upper layer of the metal oxide layer. The metal alkoxide is (R ¹ ) _m -M ^1- (OR ² ) _4-m (where R ¹ and R ² each independently represents an organic group having 1 to 8 carbon atoms, M ¹ is Si, Zr The solar cell backsheet according to claim 4, wherein the solar cell backsheet is represented by: Wherein the metal alkoxide, Al- ^(OR ₃₎ 3 (provided that ^{R 3} represents an organic group having 1 to 8 carbon atoms) solar battery back sheet according to claim 4, characterized by being represented by.

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