WO2013118570A1 - Protective sheet for solar cell, and solar cell module - Google Patents

Abstract

Provided is a solar cell protective sheet (1A) comprising a laminated base material (11), an adhesive layer (12), and a thermoplastic resin layer (13A), the thermoplastic resin layer (13A) containing homo-polypropylene, and random polypropylene and/or a thermoplastic elastomer. The solar cell protective sheet (1A) has excellent bonding to the sealant of a solar cell module, and minimal curling.

Description

Protective sheet for solar cell and solar cell module

The present invention relates to a solar cell protective sheet used as a surface protective sheet or back surface protective sheet of a solar cell module, and a solar cell module using the solar cell protective sheet.

Solar cell modules that convert solar light energy into electrical energy are attracting attention as a clean energy source that can generate electricity without discharging carbon dioxide in response to environmental problems such as air pollution and global warming.

In general, a solar cell module is made of a crystalline silicon, amorphous silicon, or the like that performs photoelectric conversion, a sealing material that includes an electrical insulator that seals the solar cell, and a surface (light-receiving surface) of the sealing material. The surface protection sheet (front sheet) laminated | stacked on this and the back surface protection sheet (back sheet | seat) laminated | stacked on the back surface of the sealing material. In order to provide the solar cell module with the weather resistance and durability that can withstand long-term use outdoors, the solar cell module and sealing material are protected from wind, rain, moisture, dust, mechanical shock, etc. It is necessary to keep the inside of the interior sealed from the outside air. For this reason, the protection sheet for solar cells is required to have moisture resistance and weather resistance that can withstand long-term use.

Patent Document 1 discloses a solar cell module in which a silicon power generation element is sealed with a sealing material made of an ethylene-vinyl acetate copolymer sheet, and a back sheet is laminated on the back surface of the sealing material. As a back sheet, a sheet in which a fluorine-based plastic film having weather resistance (Tedlar film manufactured by DuPont) is bonded to one side or both sides of a layer that prevents water vapor permeation, such as metal, is disclosed. This back sheet is heat-bonded to the sealing material.

However, the conventional back sheet as in Patent Document 1 has a problem that the back sheet peels off from the sealing material and water vapor enters the sealing material because of low adhesion to the sealing material. Therefore, it has been proposed to provide a heat-sealable layer on the back sheet to improve the adhesion to the above-mentioned sealing material.

For example, Patent Document 2 discloses a back sheet laminated on the back surface of a filler in a solar cell module using an ethylene-vinyl acetate copolymer as a filler (encapsulant), and includes an ethylene-vinyl acetate copolymer. A laminate in which a heat-fusible layer made of a heat-fusible resin mainly composed of a polymer or the like is laminated on a heat-resistant film is disclosed.

Patent Document 3 discloses a back sheet in which an inorganic oxide layer, an adhesive layer, and a thermoplastic resin layer (heat-fusible layer) are sequentially laminated on one surface of a base film, What the layer consists of polypropylene is disclosed.

Japanese Patent Application Laid-Open No. 6-177412 JP 2008-108947 A JP 2008-270685 A

When an ethylene-vinyl acetate copolymer is used as the heat-fusible layer as in the back sheet in Patent Document 2, when the thickness of the heat-fusible layer is increased or the thickness of the heat-resistant film is reduced, Curling is likely to occur on the backsheet. In addition, since the ethylene-vinyl acetate copolymer has a large linear expansion coefficient, there is a problem that the curl amount becomes large particularly in a low temperature environment. Further, when the heat-fusible layer is laminated on the heat-resistant film by the extrusion coating method, the heat-fusible layer is contracted by cooling and a curl is generated. If the solar cell module is warped along with the curl of the back sheet, not only will the malfunction occur when the solar cell module is installed, but the solar cell module may be damaged.

On the other hand, the polypropylene used as the heat-fusible layer in Patent Document 3 has high rigidity and a small coefficient of linear expansion, so that the resulting backsheet is hardly curled, but has insufficient adhesion to the sealing material. There is a problem that there is.

The present invention has been made in view of such a situation, and is excellent in adhesion to a sealing material of a solar cell module, and has a solar cell protective sheet in which curling is suppressed, and a sealing material and a protective sheet. It aims at providing the solar cell module which was excellent in adhesiveness of this, and the curvature was suppressed.

In order to achieve the above object, first, the present invention provides a protective sheet for a solar cell comprising at least a thermoplastic resin layer containing homopolypropylene and random polypropylene and / or a thermoplastic elastomer. Provided (Invention 1)

The solar cell protective sheet according to the invention (Invention 1) is homopolypropylene having high rigidity and low linear expansion coefficient, random polypropylene and / or thermoplasticity having flexibility, low melting point, and excellent heat-fusibility. By providing the thermoplastic resin layer containing the elastomer, the adhesiveness of the solar cell module to the sealing material is excellent, and curling is suppressed.

Secondly, the present invention includes at least a thermoplastic resin layer including a first layer containing random polypropylene and / or a thermoplastic elastomer, and a second layer containing homopolypropylene laminated on the first layer. A protective sheet for solar cells is provided (Invention 2).

The solar cell protective sheet according to the invention (Invention 2) has a first layer containing a random polypropylene and / or a thermoplastic elastomer having flexibility, a low melting point, and excellent heat-fusibility. Curling is suppressed by providing the second layer containing homopolypropylene having excellent adhesion to the sealing material of the battery module and having high rigidity and a small linear expansion coefficient.

In the above invention (Invention 2), the first layer preferably further contains homopolypropylene (Invention 3).

In the above inventions (Inventions 2 and 3), the second layer preferably further contains random polypropylene (Invention 4).

Third, the present invention includes a first layer containing random polypropylene and / or a thermoplastic elastomer, a second layer containing homopolypropylene laminated on the first layer, and laminated on the second layer. A solar cell protective sheet comprising at least a thermoplastic resin layer including a third layer containing random polypropylene and / or a thermoplastic elastomer is provided (Invention 5).

The solar cell protective sheet according to the above invention (Invention 5) is provided with a first layer and a third layer containing random polypropylene and / or thermoplastic elastomer having flexibility, a low melting point, and excellent heat-fusibility. Thus, the sealing material of the solar cell module is excellent on one surface, and the other surface is excellent in adhesiveness to other layers (for example, an adhesive layer, a base material, another thermoplastic resin layer, etc.) By providing the second layer containing homopolypropylene having high rigidity and a small linear expansion coefficient, curling is suppressed.

In the above invention (Invention 5), it is preferable that the first layer and / or the third layer further contain homopolypropylene (Invention 6).

In the above inventions (Inventions 5 and 6), the second layer preferably further contains random polypropylene (Invention 7).

In the above inventions (Inventions 5 to 7), when a pigment is contained in any of the layers, the second layer is made of titanium oxide, talc, magnesium oxide, cerium oxide, barium sulfate, calcium carbonate, and carbon black. It is preferable to further contain at least one pigment selected from the group (Invention 8).

In the above inventions (Inventions 1 to 8), a substrate may be further provided (Invention 9).

In the above invention (Invention 9), it is preferable to further include a fluororesin layer laminated on the substrate (Invention 10).

In the above inventions (Inventions 2 to 4), a fluororesin layer laminated on the second layer may be further provided (Invention 11).

In the above inventions (Inventions 9 and 10), the thermoplastic resin layer and the base material may be laminated via an adhesive layer (Invention 12).

In the above inventions (Inventions 9 and 10), the thermoplastic resin layer may be formed by extrusion coating on the substrate (Invention 13).

In the said invention (invention 9 and 10), the said thermoplastic resin layer and the said base material may be laminated | stacked through the 2nd thermoplastic resin layer, In that case, the said 2nd thermoplastic resin The layer is mainly composed of a copolymer of ethylene and at least one selected from the group consisting of (meth) acrylic acid, (meth) acrylic acid ester, glycidyl (meth) acrylate, vinyl acetate and maleic anhydride. (Invention 14)

In the above invention (Invention 14), it is preferable that the thermoplastic resin layer and the second thermoplastic resin layer are formed by extrusion coating on the substrate (Invention 15).

In the above inventions (Inventions 1 to 15), the thermoplastic resin layer preferably has a thermal shrinkage of 1.0% or less when the thermoplastic resin layer is heated at 150 ° C. for 30 minutes (Invention 16). .

In the above inventions (Inventions 1 to 16), the thermoplastic resin layer is preferably a layer bonded to a sealing material constituting the solar cell module (Invention 17).

4thly this invention is a solar cell module provided with the photovoltaic cell, the sealing material which seals the said photovoltaic cell, and the protective sheet laminated | stacked on the said sealing material, Comprising: The solar cell module comprises the protective sheet for solar cells (invention 17), and the protective sheet is bonded to the sealing material through the thermoplastic resin layer (invention 18). ).

The protective sheet for solar cell according to the present invention has an excellent effect that the adhesive strength to the sealing material of the solar cell module is high and the curl amount is small. Moreover, in the solar cell module which concerns on this invention, it is excellent in the adhesiveness of a sealing material and a protective sheet, and the curvature resulting from the curl of a protective sheet is suppressed.

It is a schematic sectional drawing of the protection sheet for solar cells which concerns on the 1st Embodiment of this invention. It is a schematic sectional drawing of the protection sheet for solar cells which concerns on the 2nd Embodiment of this invention. It is a schematic sectional drawing of the protection sheet for solar cells which concerns on the 3rd Embodiment of this invention. It is a schematic sectional drawing of the protection sheet for solar cells which concerns on the 4th Embodiment of this invention. It is a schematic sectional drawing of the protection sheet for solar cells which concerns on the 5th Embodiment of this invention. It is a schematic sectional drawing of the protection sheet for solar cells which concerns on the 6th Embodiment of this invention. It is a schematic sectional drawing of the solar cell module which concerns on one Embodiment of this invention. It is a schematic sectional drawing of the solar cell module which concerns on other embodiment of this invention.

Hereinafter, embodiments of the present invention will be described.
[Protective sheet for solar cell (1)]
As shown in FIG. 1, the solar cell protective sheet 1A according to the first embodiment is formed by laminating a base material 11, an adhesive layer 12, and a thermoplastic resin layer 13A in this order from the top. The material 11 and the thermoplastic resin layer 13 </ b> A are bonded via the adhesive layer 12. This solar cell protective sheet 1A is used as a surface protective sheet (front sheet) or a back surface protective sheet (back sheet) of a solar cell module (the same applies to the following embodiments).

As the base material 11, it is generally sufficient that the base material 11 has electrical insulation and the thermoplastic resin layer 13 </ b> A can be laminated, and a material mainly composed of a resin film is usually used. In order to improve the water vapor barrier property, a vapor deposition layer such as silica may be formed on the surface of the resin film, or a metal foil such as aluminum may be laminated.

As the resin film used for the substrate 11, a resin film generally used as a resin film in a solar cell module back sheet is selected. Examples of such resin films include polyolefin resins such as polyethylene and polypropylene, polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate, polyamide resins such as nylon (trade name), polycarbonate resins, and polystyrene. A film made of a resin such as a resin, a polyacrylonitrile resin, a polyvinyl chloride resin, a polyvinyl acetal resin, a polyphenylene sulfide resin, a polyphenylene ether resin, or a fluorine resin is used. Among these resin films, a film made of a polyester resin is preferable, and a PET film is particularly preferable.

In addition, the said resin film may contain various additives, such as a pigment, a ultraviolet absorber, a ultraviolet stabilizer, a flame retardant, a plasticizer, an antistatic agent, a lubricant, and an antiblocking agent, as needed.

The surface of the substrate 11 on which the adhesive layer 12 is laminated is preferably subjected to surface treatment such as corona treatment, plasma treatment, primer treatment, etc. in order to improve adhesion to the adhesive layer 12.

The thickness of the base material 11 is appropriately set based on electrical insulation properties, water vapor barrier properties, etc. required for the solar cell module. For example, when the substrate 11 is a resin film, the thickness is preferably 10 to 300 μm. More specifically, when the substrate 11 is a PET film, the thickness is preferably 10 to 300 μm, more preferably 20 to 250 μm, from the viewpoint of electrical insulation and weight reduction. It is particularly preferable that the thickness is ˜200 μm.

The adhesive layer 12 is composed of an adhesive having adhesiveness to the base material 11 and the thermoplastic resin layer 13A. Examples of such adhesives include acrylic adhesives, polyurethane adhesives, epoxy adhesives, polyester adhesives, polyester polyurethane adhesives, and the like. These adhesives may be used individually by 1 type, and may be used in combination of 2 or more type.

The thickness of the adhesive layer 12 is not particularly limited as long as the effects of the present invention are not impaired, but it is usually preferably 1 to 20 μm, and particularly preferably 3 to 10 μm.

The thermoplastic resin layer 13A in the present embodiment is for bonding the solar cell protective sheet 1A to the sealing material of the solar cell module, but the present invention is not limited to this. The thermoplastic resin layer 13A in the present embodiment is a single layer.

The thermoplastic resin layer 13A contains homopolypropylene and random polypropylene and / or thermoplastic elastomer. Homopolypropylene has high rigidity and a small linear expansion coefficient. Therefore, the thermoplastic resin layer 13A contains homopolypropylene, so that the obtained solar cell protective sheet 1A has high dimensional stability and curls even in a low temperature environment. Is unlikely to occur. On the other hand, random polypropylene and thermoplastic elastomer are flexible, have a low melting point, and are excellent in heat fusibility. Therefore, the solar resin obtained by containing the random polypropylene and / or thermoplastic elastomer in the thermoplastic resin layer 13A. The battery protective sheet 1A has excellent adhesion to the sealing material of the solar cell module.

Homopolypropylene is a homopolymer of propylene. The density of this homopolypropylene is preferably 890 to 910 kg / m ³ .

The melt mass flow rate (MFR) of the homopolypropylene is preferably 0.1 to 40 g / 10 min, particularly preferably 0.5 to 35 g / 10 min, and preferably 1 to 30 g / 10 min. Further preferred. Here, the MFR in the present specification is a value measured according to a JIS K7210: 1999 plastic-thermoplastic melt mass flow rate (MFR) and melt volume flow rate (MVR) test method.

The random polypropylene is preferably a copolymer of propylene and one or more of α-olefins having 2 to 20 carbon atoms excluding propylene. The α-olefin having 2 to 20 carbon atoms excluding propylene is preferably ethylene and / or 1-butene. Accordingly, the random polypropylene is preferably a copolymer of propylene and ethylene, a copolymer of propylene and 1-butene, and a copolymer of propylene, ethylene and 1-butene. Among these, a copolymer of propylene and ethylene is particularly preferable. These random polypropylenes can be used alone or in a mixture of two or more.

The content of monomer components other than propylene in the random polypropylene is preferably 1 to 10% by mass, and particularly preferably 1 to 5% by mass.

Preferably the density of the random polypropylene 890 to a 920 kg / ^{m 3,} particularly preferably 890 to a 920 kg / ^{m 3,} more preferably from 900 ~ 915kg / ^{m 3.}

The melt mass flow rate (MFR) of the random polypropylene is preferably 0.1 to 40 g / 10 min, particularly preferably 0.5 to 35 g / 10 min, and 1 to 30 g / 10 min. Further preferred.

Examples of thermoplastic elastomers include polyolefin-based thermoplastic elastomers, styrene-based thermoplastic elastomers (styrene-butadiene-based thermoplastic elastomers, styrene-isoprene-based thermoplastic elastomers, etc.), polyester-based thermoplastic elastomers, polyurethane-based thermoplastic elastomers, polychlorinated elastomers. Examples thereof include vinyl-based thermoplastic elastomers and nylon-based thermoplastic elastomers. Among them, polyolefin-based thermoplastic elastomers are preferable. The polyolefin-based thermoplastic elastomer has a particularly high affinity for a sealing material made of an ethylene-vinyl acetate copolymer which is the same polyolefin-based resin, and is extremely excellent in adhesiveness. A thermoplastic elastomer can also be used individually by 1 type, and 2 or more types can also be mixed and used for it.

Examples of the hard segment of the polyolefin-based thermoplastic elastomer include polyethylene and polypropylene, and among them, a propylene homopolymer is preferable. Examples of the soft segment of the polyolefin-based thermoplastic elastomer include an ethylene-propylene copolymer and an ethylene-propylene-nonconjugated diene copolymer. The soft segment may be non-crosslinked, partially crosslinked, or completely crosslinked. In the above-mentioned polyolefin-based thermoplastic elastomer, the hard segment and the soft segment are usually blended, but are not limited thereto.

The compounding ratio of the hard segment and the soft segment is preferably 10 to 50% by mass for the hard segment and 50 to 90% by mass for the soft segment.

The melt mass flow rate (MFR) of the thermoplastic elastomer is preferably 0.1 to 40 g / 10 min, particularly preferably 0.5 to 35 g / 10 min, and further preferably 1 to 30 g / 10 min. preferable.

When the thermoplastic resin layer 13A contains two components of homopolypropylene and random polypropylene, the blending amount of random polypropylene with respect to 100 parts by mass of homopolypropylene is preferably 20 to 100 parts by mass, particularly 30 to 90 parts by mass. Part, more preferably 40 to 80 parts by weight.

When the thermoplastic resin layer 13A contains two components of homopolypropylene and thermoplastic elastomer, the blending amount of the thermoplastic elastomer with respect to 100 parts by mass of homopolypropylene is preferably 20 to 100 parts by mass, particularly 30 to 30 parts by mass. The amount is preferably 90 parts by mass, and more preferably 40 to 80 parts by mass.

When the thermoplastic resin layer 13A contains three components of homopolypropylene, random polypropylene and thermoplastic elastomer, the blending amount of random polypropylene with respect to 100 parts by mass of homopolypropylene is preferably 20 to 200 parts by mass, particularly The amount is preferably 20 to 150 parts by mass, and more preferably 20 to 100 parts by mass. The blending amount of the thermoplastic elastomer with respect to 100 parts by mass of homopolypropylene is preferably 20 to 200 parts by mass, particularly preferably 20 to 150 parts by mass, and more preferably 20 to 100 parts by mass. Is preferred.

In addition to the above components, the thermoplastic resin layer 13A contains various additives such as pigments, ultraviolet absorbers, ultraviolet stabilizers, flame retardants, plasticizers, antistatic agents, lubricants, and antiblocking agents as necessary. You may go out.

The thickness of the thermoplastic resin layer 13A is not particularly limited as long as it exhibits desired adhesion to the adherend and does not impair the effects of the present invention. Specifically, the thickness of the thermoplastic resin layer 13A is preferably 1 to 200 μm, more preferably 10 to 180 μm, and more preferably 50 to 150 μm from the viewpoint of electrical insulation and weight reduction. Particularly preferred is 80 to 120 μm.

In addition, a vapor deposition layer, a metal sheet, etc. may be provided in addition to the fluororesin layer described later on the surface (upper surface in FIG. 1) on which the thermoplastic resin layer 13A of the base material 11 is not laminated (the following). The same applies to the embodiment).

When the thermoplastic resin layer 13A is heated at 150 ° C. for 30 minutes, the thermal shrinkage rate of the thermoplastic resin layer 13A is preferably 1.0% or less, and particularly preferably 0.5% or less ( The same applies to the following embodiments). The method for measuring the heat shrinkage rate is as shown in the test examples described later. When the thermal contraction rate of the thermoplastic resin layer 13A is small as described above, curling that can occur in the solar cell protective sheet 1A can be more effectively suppressed.

In order to manufacture the solar cell protective sheet 1A, the thermoplastic resin layer 13A is formed by extrusion molding or the like, while an adhesive coating liquid constituting the adhesive layer 12 is formed on one surface of the substrate 11 (if necessary) The adhesive layer 12 is formed by applying a solvent), and the thermoplastic resin layer 13A is laminated on the adhesive layer 12.

The coating method of the adhesive coating solution is not particularly limited, and examples thereof include a bar coating method, a die coating method, and a gravure coating method.

The solar cell protective sheet 1A described above has excellent adhesion to the sealing material of the solar cell module by having the thermoplastic resin layer 13A containing homopolypropylene and random polypropylene and / or thermoplastic elastomer, Moreover, since the dimensional stability is high and the curl amount is small, warpage occurring in the solar cell module can be suppressed. Furthermore, since the thermoplastic resin layer 13A in this embodiment is a single layer, it is advantageous in terms of material cost and manufacturing cost.

[Protective sheet for solar cell (2)]
As shown in FIG. 2, the solar cell protective sheet 1B according to the second embodiment is formed by laminating a base material 11, an adhesive layer 12, and a thermoplastic resin layer 13B in this order from the top. The material 11 and the thermoplastic resin layer 13 </ b> B are bonded via the adhesive layer 12.

The thermoplastic resin layer 13B has a two-layer structure including a first layer 131 located on the side of the sealing material (lower surface in FIG. 2) and a second layer 132 located on the adhesive layer 12 side. ing.

The first layer 131 contains random polypropylene and / or thermoplastic elastomer. Random polypropylene and thermoplastic elastomer are flexible, have a low melting point, and are excellent in heat-fusibility. Therefore, the first layer 131 located on the adhesive surface side with the sealing material in the thermoplastic resin layer 13B is made of random polypropylene and // By containing a thermoplastic elastomer, the protective sheet 1B for solar cells obtained becomes excellent in the adhesiveness with respect to the sealing material of a solar cell module. The first layer 131 is also excellent in adhesiveness with the second layer 132.

On the other hand, the second layer 132 contains homopolypropylene. Since the homopolypropylene has high rigidity and a small linear expansion coefficient, the thermoplastic resin layer 13B has the second layer 132 containing the homopolypropylene, so that the obtained solar cell protective sheet 1B has high dimensional stability, In particular, curling is unlikely to occur even in a low temperature environment.

As the random polypropylene and the thermoplastic elastomer contained in the first layer 131, those similar to the random polypropylene and the thermoplastic elastomer in the thermoplastic resin layer 13A of the solar cell protective sheet 1A according to the first embodiment are used. be able to. Moreover, as the homopolypropylene contained in the second layer 132, the same homopolypropylene as that in the thermoplastic resin layer 13A of the solar cell protective sheet 1A according to the first embodiment can be used.

The first layer 131 may contain only random polypropylene, may contain only a thermoplastic elastomer, or may contain both random polypropylene and thermoplastic elastomer. It is preferable to contain both elastomers. Thermoplastic elastomers have better adhesion than random polypropylene, but have the disadvantage of being easily shrunk. Random polypropylene has the advantage that it is less adhesive than thermoplastic elastomer but is less likely to shrink. Therefore, by containing both, the adhesiveness and the performance of suppressing shrinkage can be balanced.

When the first layer 131 contains both random polypropylene and thermoplastic elastomer, the blending ratio thereof is preferably 20 to 200 parts by mass of the thermoplastic elastomer with respect to 100 parts by mass of the random polypropylene. The amount is preferably 30 to 180 parts by mass, and more preferably 50 to 150 parts by mass.

The first layer 131 preferably further contains homopolypropylene together with random polypropylene and / or thermoplastic elastomer. When the first layer 131 further contains homopolypropylene, the first layer 131 has a certain degree of rigidity, and the linear expansion coefficient of the first layer 131 approaches the linear expansion coefficient of the second layer 132. Thus, the curl suppressing effect can be improved. As homopolypropylene, the same thing as the homopolypropylene in the thermoplastic resin layer 13A of the solar cell protective sheet 1A according to the first embodiment can be used.

When the first layer 131 contains two components of random polypropylene and homopolypropylene, the blending amount of homopolypropylene with respect to 100 parts by mass of random polypropylene is preferably 20 to 200 parts by mass, particularly 50 to 200 parts by mass. Preferably, the amount is 100 to 180 parts by mass.

When the first layer 131 contains two components of a thermoplastic elastomer and a homopolypropylene, the blending amount of the homopolypropylene with respect to 100 parts by mass of the thermoplastic elastomer is preferably 20 to 200 parts by mass, particularly 30 to 180 parts. The amount is preferably part by mass, and more preferably 50 to 150 parts by mass.

When the first layer 131 contains three components of random polypropylene, thermoplastic elastomer and homopolypropylene, the blending amount of homopolypropylene with respect to 100 parts by mass of the total amount of random polypropylene and thermoplastic elastomer is 20 to 200 parts by mass. It is preferably 30 to 180 parts by mass, more preferably 50 to 150 parts by mass.

The second layer 132 preferably contains random polypropylene together with homopolypropylene. When the second layer 132 contains random polypropylene, which is an essential component of the first layer 131, the linear expansion coefficient of the second layer 132 approaches the linear expansion coefficient of the first layer 131, thereby improving the curl suppressing effect. Can do. In addition, the affinity between the two layers can be improved, and the adhesion between the first layer 131 and the second layer 132 can also be improved. As a random polypropylene, the same thing as the random polypropylene in the thermoplastic resin layer 13A of the solar cell protective sheet 1A according to the first embodiment can be used.

The second layer 132 preferably does not contain a thermoplastic elastomer in order to ensure the mechanical strength and accuracy of the solar cell protective sheet 1B.

When the second layer 132 contains homopolypropylene and random polypropylene, the blending amount of the random polypropylene with respect to 100 parts by mass of the homopolypropylene is preferably 20 to 100 parts by mass, particularly 30 to 90 parts by mass. It is preferable that the amount is 40 to 80 parts by mass.

In addition to the above components, the first layer 131 and the second layer 132 may be various types such as pigments, ultraviolet absorbers, ultraviolet stabilizers, flame retardants, plasticizers, antistatic agents, lubricants, antiblocking agents, etc. An additive may be included. However, if the first layer 131 contains a pigment, the adhesiveness is lowered and the adhesion to the sealing material may be lowered. Therefore, the first layer 131 preferably does not contain a pigment.

Examples of the pigment include coloring pigments such as titanium oxide and carbon black, and extender pigments such as calcium carbonate and barium sulfate. One kind can be used alone, or two or more kinds can be used in combination. .

The thickness of the first layer 131 is preferably 5 to 150 μm, particularly preferably 10 to 100 μm, and further preferably 15 to 75 μm, from the viewpoint of ensuring adhesion with the sealing material. .

The thickness of the second layer 132 is preferably 10 to 300 μm, particularly preferably 30 to 200 μm, and further preferably 50 to 150 μm, from the viewpoint of ensuring curling suppression performance.

Here, the ratio of the thickness of the first layer 131 to the thickness of the second layer 132 is preferably 1: 9 to 7: 3, and is 1.5: 8.5 to 6.5: 3.5. Particularly preferred is 2: 8 to 6: 4. When the ratio between the thickness of the first layer 131 and the thickness of the second layer 132 is within the above range, the solar cell protective sheet 1B according to this embodiment has a smaller curl amount.

In order to manufacture the solar cell protective sheet 1B, the thermoplastic resin layer 13B is formed by coextrusion molding of the first layer 131 and the second layer 132, while the adhesive layer 12 is formed on one surface of the substrate 11. The adhesive layer 12 is formed by applying an adhesive coating liquid (containing a solvent if necessary) that constitutes the above, and the second layer 132 of the thermoplastic resin layer 13B is overlaid on the adhesive layer 12. The thermoplastic resin layer 13B may be laminated.

The solar cell protective sheet 1B described above has a thermoplastic resin layer 13B composed of a first layer 131 containing random polypropylene and / or a thermoplastic elastomer and a second layer 132 containing homopolypropylene. Since the solar cell module has excellent adhesion to the sealing material, has high dimensional stability, and has a small amount of curl, it is possible to suppress warpage occurring in the solar cell module.

[Protective sheet for solar cell (3)]
As illustrated in FIG. 3, the solar cell protective sheet 1 </ b> C according to the third embodiment includes a thermoplastic resin layer 13 </ b> C and a fluororesin layer 14 provided on one surface (upper surface in FIG. 3) of the thermoplastic resin layer 13 </ b> C. It consists of. The thermoplastic resin layer 13 </ b> C has a two-layer structure including a first layer 131 located on the adhesive surface (lower surface in FIG. 3) side with the sealing material and a second layer 132 located on the fluororesin layer 14 side. ing.

The first layer 131 and the second layer 132 of the thermoplastic resin layer 13C are the same as the first layer 131 and the second layer 132 of the thermoplastic resin layer 13B in the solar cell protective sheet 1B according to the second embodiment. The thermoplastic resin layer 13C can be manufactured in the same manner as the thermoplastic resin layer 13B.

Unlike the solar cell protective sheet 1B according to the second embodiment, the solar cell protective sheet 1C does not include the base material 11 and the adhesive layer 12, but the homopolypropylene contained in the second layer 132 is: Since the rigidity is high and it has a certain mechanical strength, the second layer 132 itself can serve as the base material 11. In addition, the first layer 131 ensures adhesion to the sealing material. In addition, since this protective sheet 1C for solar cells does not include the base material 11, the problem of curling due to the difference in thermal contraction rate with the base material 11 does not occur.

The solar cell protective sheet 1C in the present embodiment includes the fluororesin layer 14 on the surface side of the second layer 132 in the thermoplastic resin layer 13C. By providing the fluororesin layer 14 in this manner, the weather resistance of the solar cell protective sheet 1C is improved. Note that the surface of the second layer 132 on which the fluororesin layer 14 is laminated is subjected to surface treatment such as corona treatment, plasma treatment, and primer treatment in order to improve adhesion to the fluororesin layer 14. It is preferable.

The fluororesin layer 14 is not particularly limited as long as it contains fluorine. For example, the fluororesin layer 14 includes a sheet having a fluorine-containing resin (fluorine-containing resin sheet) or a coating film formed by applying a paint containing the fluorine-containing resin. Is done. Among these, from the viewpoint of making the fluororesin layer 14 thinner in order to reduce the weight of the solar cell protective sheet 1C, a coating film formed by applying a paint having a fluorine-containing resin is preferable.

As the fluorine-containing resin sheet, for example, a sheet obtained by processing a resin mainly composed of polyvinyl fluoride (PVF), ethylene chlorotrifluoroethylene (ECTFE), or ethylene tetrafluoroethylene (ETFE) is used. Examples of the resin mainly composed of PVF include “Tedlar” (trade name) manufactured by DuPont. Examples of the resin mainly composed of ECTFE include “Halar” (trade name) manufactured by Solvay Solexis. Examples of the resin mainly composed of ETFE include “Fluon” (trade name) manufactured by Asahi Glass Co., Ltd.

When the fluororesin layer 14 is a fluorine-containing resin sheet, the fluororesin layer 14 is laminated on the second layer 132 of the thermoplastic resin layer 13C via an adhesive layer. The adhesive layer is composed of an adhesive having adhesiveness to the second layer 132 and the fluorine-containing resin sheet. Examples of such adhesives include acrylic adhesives, polyurethane adhesives, epoxy adhesives, polyester adhesives, and polyester polyurethane adhesives. These adhesives may be used individually by 1 type, and may be used in combination of 2 or more type.

On the other hand, when the fluororesin layer 14 is a coating film formed by applying a paint having a fluorine-containing resin, the paint containing the fluorine-containing resin is usually used as the second layer of the thermoplastic resin layer 13C without using an adhesive layer. By directly applying to 132, the fluororesin layer 14 is laminated on the second layer 132.

The coating material containing a fluorine-containing resin is not particularly limited as long as it is dissolved in a solvent or dispersed in water and can be applied.

The fluorine-containing resin contained in the paint is not particularly limited as long as it does not impair the effects of the present invention and contains fluorine. However, it is usually soluble in a paint solvent (organic solvent or water) and can be crosslinked. Things are used. As the fluorine-containing resin, it is preferable to use a fluoroolefin resin having a crosslinkable functional group. Examples of the crosslinkable functional group include a hydroxyl group, a carboxyl group, an amino group, and a glycidyl group.

Specific examples of the fluoroolefin resin having a crosslinkable functional group include “LUMIFLON” (product name) manufactured by Asahi Glass Co., Ltd., “CEFRAL COAT” (product name) manufactured by Central Glass Co., Ltd., and “FLUONATE” (product manufactured by DIC Corporation). Name) and other polymers based on chlorotrifluoroethylene (CTFE) as a main component, and polymers based on tetrafluoroethylene (TFE) such as “ZEFFLE” (trade name) manufactured by Daikin Industries, Ltd. .

The coating material may contain a crosslinking agent, a crosslinking catalyst, a solvent and the like in addition to the fluorine-containing resin described above, and may further contain fine particles such as titanium oxide and silica if necessary.

The coating film of fluorine-containing resin is preferably cross-linked with a cross-linking agent in order to improve weather resistance and scratch resistance. The crosslinking agent is not particularly limited as long as the effects of the present invention are not impaired, and metal chelates, silanes, isocyanates, or melamines are preferably used. Assuming that the solar cell protective sheet 1C is used outdoors for a long period of time, aliphatic isocyanates are preferable as the crosslinking agent from the viewpoint of weather resistance.

As a method for applying the coating material to the second layer 132, a known method is used. For example, the obtained fluororesin layer 14 may have a desired thickness by a bar coating method, a die coating method, a gravure coating method, or the like. What is necessary is just to apply.

The thickness of the fluororesin layer 14 is set in consideration of weather resistance, weight reduction, etc., preferably 5 to 50 μm, particularly preferably 10 to 30 μm.

Here, the fluororesin layer 14 may be made of a thermoplastic material, and in that case, the fluororesin layer 14 can be formed by an extrusion method instead of coating a paint. Such a fluororesin layer 14 may be directly extrusion-coated on the thermoplastic resin layer 13C, or other thermoplastics that can increase the adhesive force between the thermoplastic resin layer 13C and the thermoplastic resin layer 13C. Another thermoplastic resin layer and the fluororesin layer 14 may be coextrusion coated with a resin layer interposed. Further, the fluororesin layer 14 may be coextruded with the first layer 131 and the second layer 132 of the thermoplastic resin layer 13C.

The above-mentioned fluororesin layer 14 is preferably provided also on the surface (upper surface in the drawing) of the base material 11 in another embodiment.

The solar cell protective sheet 1C described above is mainly composed of the thermoplastic resin layer 13C composed of the first layer 131 containing random polypropylene and / or a thermoplastic elastomer and the second layer 132 containing homopolypropylene. By this, it is excellent in the adhesiveness with respect to the sealing material of a solar cell module, and since it hardly curls, the curvature which arises in a solar cell module can be suppressed. Furthermore, since the solar cell protective sheet 1C in this embodiment does not include a base material and an adhesive layer for adhering other layers to the base material, the solar cell protective sheet 1C is thinned. This is advantageous in terms of material cost and manufacturing cost.

[Protective sheet for solar cell (4)]
As shown in FIG. 4, the solar cell protective sheet 1D according to the fourth embodiment is formed by laminating a base material 11, an adhesive layer 12, and a thermoplastic resin layer 13D in this order from the top. The material 11 and the thermoplastic resin layer 13 </ b> D are bonded via the adhesive layer 12.

The thermoplastic resin layer 13D includes a first layer 131 located on the adhesive surface (lower surface in FIG. 4) side with the sealing material, a third layer 133 located on the adhesive layer 12 side, the first layer 131, and the first layer 131. It has a three-layer structure including the second layer 132 positioned between the three layers 133.

The first layer 131 and the third layer 133 of the thermoplastic resin layer 13D are made of the same material as the first layer 131 of the thermoplastic resin layer 13B in the solar cell protective sheet 1B according to the second embodiment, The second layer 132 of the thermoplastic resin layer 13D is made of the same material as the second layer 132 of the thermoplastic resin layer 13B.

Therefore, the solar cell protective sheet 1D obtained by the presence of the first layer 131 on the adhesive surface side with the sealing material in the thermoplastic resin layer 13D has excellent adhesion to the sealing material of the solar cell module. It will be a thing. In addition, since the second layer 132 is present in the thermoplastic resin layer 13D, the obtained solar cell protective sheet 1D has high dimensional stability, and curling is not likely to occur even in a low temperature environment.

On the other hand, if the third layer 133 made of the same material as the first layer 131 is present on the adhesive layer 12 side of the thermoplastic resin layer 13D, the thermoplastic resin layer 13D has a symmetrical structure in the thickness direction, and more curling occurs. It will be difficult. Moreover, when the 3rd layer 133 excellent in adhesiveness exists in the adhesive bond layer 12 side of the thermoplastic resin layer 13D, adhesiveness with the adhesive bond layer 12 will improve more.

The thickness of the first layer 131 and the third layer 133 is preferably 5 to 100 μm, particularly preferably 5 to 70 μm, and further preferably 10 to 50 μm.

The thickness of the second layer 132 is preferably 10 to 200 μm, particularly preferably 15 to 180 μm, and further preferably 25 to 150 μm, from the viewpoint of ensuring curling suppression performance. The thickness of the second layer 132 is preferably 30 to 95% of the thickness of the thermoplastic resin layer 13D, particularly preferably 40 to 90%, and more preferably 45 to 80%. Further preferred.

To manufacture the solar cell protective sheet 1D, the first layer 131, the second layer 132, and the third layer 133 are coextruded to form the thermoplastic resin layer 13D. The adhesive layer 12 is formed by applying an adhesive coating liquid (containing a solvent if necessary) constituting the adhesive layer 12, and the third thermoplastic resin layer 13 </ b> D of the thermoplastic resin layer 13 </ b> D is formed on the adhesive layer 12. The thermoplastic resin layer 13D may be stacked by stacking the layers 133.

The solar cell protective sheet 1D described above includes a thermoplastic resin layer 13D including a first layer 131 and a third layer 133 containing random polypropylene and / or a thermoplastic elastomer, and a second layer 132 containing homopolypropylene. Therefore, since the dimensional stability is high and the curl amount is very small, the warpage occurring in the solar cell module can be effectively suppressed.

[Protective sheet for solar cell (5)]
As shown in FIG. 5, the solar cell protective sheet 1 </ b> E according to the fifth embodiment includes a base material 11 and a thermoplastic resin layer 13 </ b> E provided on one side (the lower surface in FIG. 5) of the base material 11. Is done. The thermoplastic resin layer 13E includes a first layer 131 located on the side of the adhesive surface (lower surface in FIG. 5) with the sealing material, a third layer 133 located on the substrate 11 side, the first layer 131, and the third layer. It has a three-layer structure including the second layer 132 located between the layers 133.

The first layer 131 and the third layer 133 of the thermoplastic resin layer 13E are the same as the first layer 131 and the third layer 133 of the thermoplastic resin layer 13D in the solar cell protective sheet 1D according to the fourth embodiment. The second layer 132 of the thermoplastic resin layer 13E is made of the same material as the second layer 132 of the thermoplastic resin layer 13D.

That is, the solar cell protective sheet 1E according to the present embodiment has a configuration in which the adhesive layer 12 is omitted from the solar cell protective sheet 1D according to the fourth embodiment, and the solar cell protective sheet 1D and Similarly, it has excellent adhesion to the sealing material of the solar cell module, has high dimensional stability, and has a very small curl amount even in a low-temperature environment, so it effectively suppresses the warpage that occurs in the solar cell module. Can do. Furthermore, the 3rd layer 133 located in the base material 11 side in the thermoplastic resin layer 13E shows favorable adhesiveness with respect to the base material 11 by containing a random polypropylene and / or a thermoplastic elastomer.

However, the melt mass flow rate (MFR) of the resin composition constituting each of the first layer 131, the second layer 132, and the third layer 133 of the thermoplastic resin layer 13E is 0.1 to 40 g / 10 min. It is particularly preferably 1 to 30 g / 10 min. When the MFR of the resin composition is within the above range, the first layer 131, the second layer 132, and the third layer 133 of the thermoplastic resin layer 13E can be formed by coextrusion coating.

To manufacture the solar cell protective sheet 1E, a first resin composition constituting the first layer 131 of the thermoplastic resin layer 13E, a second resin composition constituting the second layer 132, and The third resin composition constituting the third layer 133 is coextrusion-coated on at least one surface of the base material 11 so that the third resin composition is on the base material 11 side. It is preferable to form a thermoplastic resin layer 13E composed of the third layer 133 stacked on the second layer 133, the second layer 132 stacked on the third layer 133, and the first layer 131 stacked on the second layer 132. .

Specifically, using a T-die film forming machine or the like, the first resin composition, the second resin composition, and the third resin composition are respectively melted, and the base material 11 is kept at a constant speed. The molten first resin composition, second resin composition, and third resin composition are coextruded and laminated on one surface of the substrate 11 while being conveyed. A thermoplastic resin layer 13E composed of the third layer 133, the second layer 132, and the first layer 131 is formed to obtain the solar cell protective sheet 1E.

The temperature at which the resin composition forming the thermoplastic resin layer 13E is melted is such that the substrate 11 is not deformed by the temperature (heat) of the melted resin composition, and is preferably 80 to 350 ° C., and preferably 150 to 300 It is particularly preferable that the temperature is C.

Further, the discharge amount of the resin composition forming the thermoplastic resin layer 13E from the T-die film forming machine is appropriately adjusted according to the thickness of the target thermoplastic resin layer 13E and the conveyance speed of the substrate 11.

The base material 11 is transported in the longitudinal direction at a constant speed by, for example, a roll-to-roll system, and the transport speed is a discharge of a resin composition forming the thermoplastic resin layer 13E from a T-die film forming machine. It adjusts suitably according to quantity.

According to the coextrusion coating method as described above, the thermoplastic resin is applied to the substrate 11 only by coextrusion coating and laminating the resin composition melted from the T-die film forming machine on one surface of the substrate 11. The layer 13E can be firmly bonded, and the solar cell protective sheet 1E can be manufactured with high productivity and low cost. In addition, since it is not necessary to separately provide an adhesive layer, it is possible to prevent deterioration over time due to decomposition of the adhesive or the like.

[Protective sheet for solar cell (6)]
As shown in FIG. 6, the solar cell protective sheet 1F according to the sixth embodiment includes, in order from the top, the base material 11, the second thermoplastic resin layer 15, and the first thermoplastic resin layer 13F. The base material 11 and the first thermoplastic resin layer 13F are bonded to each other through the second thermoplastic resin layer 15.

The first thermoplastic resin layer 13F includes a first layer 131 located on the adhesive surface (lower surface in FIG. 6) side with the sealing material, and a third layer 133 located on the second thermoplastic resin layer 15 side. The first layer 131 and the second layer 132 located between the first layer 131 and the third layer 133 have a three-layer structure.

The first layer 131 and the third layer 133 of the thermoplastic resin layer 13F are the same as the first layer 131 and the third layer 133 of the thermoplastic resin layer 13D in the solar cell protective sheet 1D according to the fourth embodiment. The second layer 132 of the thermoplastic resin layer 13F is made of the same material as the second layer 132 of the thermoplastic resin layer 13D.

That is, the solar cell protective sheet 1F according to the present embodiment has a configuration in which the second thermoplastic resin layer 15 is provided in place of the adhesive layer 12 in the solar cell protective sheet 1D according to the fourth embodiment. It has become.

The second thermoplastic resin layer 15 includes ethylene and at least one selected from the group consisting of (meth) acrylic acid, (meth) acrylic acid ester, glycidyl (meth) acrylate, vinyl acetate, and maleic anhydride. The main component is a copolymer (hereinafter sometimes referred to as “copolymer F”). The second thermoplastic resin layer 15 made of the above material has a high adhesive force to the base material 11, particularly the base material 11 made of a resin film, and further to the base material 11 made of a polyethylene terephthalate film. Further, as described above, the first thermoplastic resin layer 13F has a high adhesive force to the sealing material of the solar cell module. Because of these high adhesive strengths, the solar cell protective sheet 1F according to this embodiment is difficult to delaminate, thereby protecting the inside of the solar cell module for a long period of time.

The copolymer F, which is the main component of the second thermoplastic resin layer 15, is amorphous (non-crystalline) at room temperature and has elasticity. Therefore, even if the first thermoplastic resin layer 13F contracts slightly when cooled from the molten state, the contraction stress can be relaxed by the second thermoplastic resin layer 15. Therefore, even when the second thermoplastic resin layer 15 and the first thermoplastic resin layer 13F are formed on the base material 11 by coextrusion coating, the stress acting toward the base material 11 is not easily generated, and therefore the sun The curl amount of the battery protection sheet 1F is extremely small. Thereby, it can suppress that a curvature arises in a solar cell module resulting from the curl of the protection sheet 1F for solar cells.

The second thermoplastic resin layer 15 has the copolymer F as a main component, preferably a copolymer of ethylene and (meth) acrylic acid, a copolymer of ethylene and (meth) acrylic acid ester, Or a copolymer of ethylene and vinyl acetate as a main component, particularly preferably a copolymer of ethylene and (meth) acrylic acid ester or a copolymer of ethylene and vinyl acetate as a main component. One of the polymers can be used alone or in combination of two or more. In this specification, (meth) acrylic acid ester means both acrylic acid ester and methacrylic acid ester. The same applies to other similar terms.

The (meth) acrylic acid ester is preferably a (meth) acrylic acid alkyl ester having an alkyl group having 1 to 18 carbon atoms, such as methyl (meth) acrylate, ethyl (meth) acrylate, (meth) acrylic. Examples thereof include propyl acid, butyl (meth) acrylate, 2-ethylhexyl acrylate and the like. Among these, methyl acrylate, butyl acrylate, 2-ethylhexyl acrylate and methyl methacrylate are preferable, butyl acrylate is particularly preferable, and one kind can be used alone or two or more kinds can be used in combination.

Specifically, preferred copolymers F include ethylene-butyl acrylate copolymer (EBA), ethylene-methyl acrylate copolymer (EMA), and the like.

The total content of (meth) acrylic acid, (meth) acrylic acid ester, (meth) acrylic acid glycidyl, vinyl acetate and maleic anhydride as monomer units in the copolymer F is 3.5-15. The mol% is preferable, and 4 to 14 mol% is more preferable. That is, in the copolymer of ethylene and (meth) acrylic acid, the content of (meth) acrylic acid, in the copolymer of ethylene and (meth) acrylic acid ester, the content of (meth) acrylic acid ester, ethylene and Content of glycidyl (meth) acrylate for copolymers with glycidyl (meth) acrylate, content of vinyl acetate for copolymers of ethylene and vinyl acetate, anhydrous for copolymers of ethylene and maleic anhydride The content of maleic acid is preferably 3.5 to 15 mol%, more preferably 4 to 14 mol%.

High adhesive strength and curl suppression to the substrate 11 described above because the content of (meth) acrylic acid, (meth) acrylic ester, glycidyl (meth) acrylate, vinyl acetate and maleic anhydride is within the above range. The effect becomes more remarkable. When the contents of (meth) acrylic acid, (meth) acrylic acid ester, glycidyl (meth) acrylate, vinyl acetate and maleic anhydride are less than 3.5 mol%, the base material 11 and the first heat Adhesive strength with respect to the plastic resin layer 13F may be low, and if it is 15 mol% or more, sufficient cohesive force cannot be obtained, and when the solar cell protective sheet 1F is wound up, there is a risk of winding slippage. There is.

The 2nd thermoplastic resin layer 15 should just contain the said copolymer F as a main component, Specifically, it is preferable to contain the said copolymer F 60 mass% or more, and 80 mass%. It is more preferable to contain above, and it is especially preferable to contain 90 mass% or more. Naturally, the second thermoplastic resin layer 15 may be made of only the copolymer F.

Melt mass flow rate of the resin composition constituting each of the copolymer F of the second thermoplastic resin layer 15 and the first layer 131, the second layer 132, and the third layer 133 of the first thermoplastic resin layer 13F ( The MFR) is preferably from 0.1 to 40 g / 10 min, particularly preferably from 1 to 30 g / 10 min. When the MFR of the resin composition is within the above range, the second thermoplastic resin layer 15 and the first layer 131, the second layer 132, and the third layer 133 of the first thermoplastic resin layer 13F are coextruded. It can be formed by coating.

In addition to the resin as the main component, the second thermoplastic resin layer 15 is made of an ultraviolet absorber, an ultraviolet stabilizer, a flame retardant, a plasticizer, an antistatic agent, a lubricant, an antiblocking agent, etc., if necessary. Various additives may be included.

The thickness of the second thermoplastic resin layer 15 is not particularly limited as long as it exhibits desired adhesiveness and stress relaxation properties to the substrate 11 and does not impair the effects of the present invention. Specifically, the thickness of the second thermoplastic resin layer 15 is preferably 5 to 150 μm, more preferably 10 to 100 μm, and particularly preferably 15 to 75 μm.

In order to manufacture the solar cell protective sheet 1F, the first resin composition constituting the first layer 131 of the first thermoplastic resin layer 13F and the second resin composition constituting the second layer 132 are used. The third resin composition constituting the third layer 133, and the fourth resin composition constituting the second thermoplastic resin layer 15, the fourth resin composition being on the substrate 11 side The second thermoplastic resin layer 15 laminated on the base material 11 and the second thermoplastic resin layer 15 laminated on the base material 11 by coextrusion coating on at least one surface of the base material 11 It is preferable to form a third layer 133, a second layer 132 laminated on the third layer 133, and a first thermoplastic resin layer 13 F composed of the first layer 131 laminated on the second layer 132.

According to the above-described coextrusion coating method, the resin composition melted from the T-die film forming machine is only coextruded and laminated on one surface of the base material 11, and then the second surface is applied to the base material 11. The thermoplastic resin layer 15 and the first thermoplastic resin layer 13F can be firmly bonded, and the solar cell protective sheet 1F can be manufactured with high productivity and low cost. In addition, since it is not necessary to separately provide an adhesive layer, it is possible to prevent deterioration over time due to decomposition of the adhesive or the like.

[Solar cell module]
FIG. 7 is a schematic cross-sectional view of a solar cell module according to an embodiment of the present invention. A solar cell module 10 according to this embodiment includes a plurality of solar cells 2 made of crystalline silicon, amorphous silicon, or the like, which are photoelectric conversion elements, and a sealing material 3 made of an electrical insulator that seals the solar cells 2. And a glass plate 4 laminated on the surface (upper surface in FIG. 7) of the sealing material 3, and a back surface protection sheet (back sheet) laminated on the back surface (lower surface in FIG. 7) of the sealing material 3. The solar cell protective sheet 1 (solar cell protective sheets 1A to 1F in the above embodiment).

The solar cell protective sheet 1 is laminated on the sealing material 3 so that the first layer 131 of the thermoplastic resin layer 13A or the thermoplastic resin layers 13B to 13F is in contact with the sealing material 3. Or the adhesive force with respect to the sealing material 3 is high by those layers containing a thermoplastic elastomer. Due to the high adhesive force, the inside of the solar cell module 10 according to the present embodiment is protected by the solar cell protective sheet 1 for a long period of time. Furthermore, since the solar cell protective sheet 1 in the present embodiment has a small amount of curl, warping of the obtained solar cell module 10 is suppressed. Therefore, it is possible to prevent problems caused when the solar cell module 10 is installed or damage of the solar cell module 10 due to warpage of the solar cell module 10.

The material of the sealing material 3 is preferably an olefin resin, and particularly from the viewpoints of high gas barrier properties against oxygen and the like, easy cross-linking, easy availability, and the like. It is preferably a coalescence (EVA). When the material of the sealing material 3 is an olefin resin, the affinity with the first layer 131 of the thermoplastic resin layer 13A or the thermoplastic resin layers 13B to 13F containing random polypropylene and / or thermoplastic elastomer is increased. Further, the adhesive force between the thermoplastic resin layers 13A to 13F and the sealing material 3 becomes higher.

The method for producing the solar cell module 10 is not particularly limited. For example, the solar cell 2 is sandwiched between two sheets constituting the encapsulant 3, and the solar cell protective sheet is provided on one exposed surface of the sheet. 1. The solar cell module 10 can be manufactured by installing the glass plate 4 on the other exposed surface and pressing and integrating them while heating. At this time, the solar cell protective sheet 1 is bonded to the sealing material 3 by thermal fusion between the thermoplastic resin layers 13A to 13F and the sealing material 3.

In addition, as shown in FIG. 8, it can replace with the glass plate 4 and can use the protection sheet 1 for solar cells as a surface protection sheet (front sheet). In this case, if a flexible substrate is used for the solar battery cell, a solar battery module having flexibility can be obtained. Thus, by making the solar cell module flexible, it becomes possible to mass-produce by roll-to-roll. In addition, since the flexible solar cell module can be fitted to an object having an arched or parabolic wall surface, it can be installed on a dome-shaped building or a soundproof wall of a highway. .

The embodiment described above is described for facilitating understanding of the present invention, and is not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

For example, in the solar cell protective sheets 1A and 1B according to the first and second embodiments, the adhesive layer 12 may be omitted as in the solar cell protective sheet 1E according to the fifth embodiment. And the 2nd thermoplastic resin layer 15 may be provided instead of the adhesive bond layer 12 like the protection sheet 1F for solar cells which concerns on 6th Embodiment.

Hereinafter, the present invention will be described more specifically with reference to examples and the like, but the scope of the present invention is not limited to these examples and the like.

[Example 1]
Using a three-layer T-die co-extruder (cylinder temperature: 230 to 250 ° C., T-die temperature: 250 ° C.), the first layer (thickness 20 μm) / second layer (thickness 135 μm) / third layer (thickness) A three-layered thermoplastic resin layer (thickness: 175 μm) having a thickness of 20 μm was formed.

The first and third layers are homopolypropylene (manufactured by Prime Polymer Co., Ltd., product name: J105G, density: 900 kg / m ³ , MFR: 9 g / 10 min), and random polypropylene (prime) that is a copolymer of propylene and ethylene. Made by Polymer Co., Ltd., product name: F329RA, density: 910 kg / m ³ , MFR: 25 g / 10 min) and polyolefin-based thermoplastic elastomer (manufactured by Prime Polymer Co., Ltd., product name: J-5710, MFR: 8 g / 10 min), 60 A film was formed with a resin composition blended at a mass ratio of 40:50.

The second layer is homopolypropylene (manufactured by Prime Polymer Co., Ltd., product name: J105G, density: 900 kg / m ³ , MFR: 9 g / 10 min) and random polypropylene (manufactured by Prime Polymer Co., Ltd.), a copolymer of propylene and ethylene. A product name: F329RA, density: 910 kg / m ³ , MFR: 25 g / 10 min) was blended at a mass ratio of 60:40, and a film was formed with a resin composition blended with 15% by mass of titanium oxide.

On the other hand, on one side of a polyethylene terephthalate (PET) film (product name: Lumirror X10S, thickness: 50 μm) as a base material, a polyurethane-based adhesive (Takenate A-515 made by Mitsui Chemicals, Inc. and Mitsui Chemicals, Inc.) A mixture of Takelac A-3 manufactured at a mass ratio of 9: 1) was applied with a Meyer bar and dried at 80 ° C. for 1 minute to form an adhesive layer having a thickness of 10 μm. And the thermoplastic resin layer of the said 3 layer structure was laminated on the adhesive bond layer, and the protective sheet for solar cells of the structure shown in FIG. 4 was obtained.

[Example 2]
The thickness of the first layer and the third layer of the three-layered thermoplastic resin layer is changed to 15 μm, the thickness of the second layer is changed to 120 μm, the total thickness is changed to 150 μm, and the thickness of the base material (PET film) A solar cell protective sheet was produced in the same manner as in Example 1 except that the thickness was changed to 75 μm.

Example 3
The thickness of the first layer and the third layer of the three-layered thermoplastic resin layer is changed to 10 μm, the thickness of the second layer is changed to 80 μm, the total thickness is changed to 100 μm, and the thickness of the base material (PET film) A solar cell protective sheet was produced in the same manner as in Example 1 except that the thickness was changed to 125 μm.

Example 4
Using a three-layer T-die co-extruder (cylinder temperature: 230 to 250 ° C., T-die temperature: 250 ° C.), the first layer (thickness 20 μm) / second layer (thickness 135 μm) / third layer (thickness) A three-layered thermoplastic resin layer (thickness: 175 μm) having a thickness of 20 μm was formed.

Random co-polymerization of homopolypropylene (manufactured by Prime Polymer Co., Ltd., product name: J105G, density: 900 kg / m ³ , MFR: 9 g / 10 min), propylene and ethylene in each of the first layer, the second layer and the third layer Random polypropylene (manufactured by Prime Polymer Co., Ltd., product name: F329RA, density: 910 kg / m ³ , MFR: 25 g / 10 min), which is a coalescence, was formed into a film with a resin composition blended at a mass ratio of 60:40.

A solar cell protective sheet was produced in the same manner as in Example 1 except that the thermoplastic resin layer having the three-layer structure was used.

[Comparative Example 1]
Except for changing the three-layered thermoplastic resin layer to a single ethylene-vinyl acetate copolymer (EVA) film (vinyl acetate content: 5 mass%, thickness: 50 μm), the same as in Example 1 A protective sheet for solar cells was produced.

[Test Example 1] <Curl amount measurement>
A test piece of 300 mm × 300 mm was cut out from the solar cell protective sheet obtained in the examples or comparative examples, and left for 24 hours in a low temperature environment condition of 4 ° C. and 50% RH. Then, the test piece was set | placed on the horizontal table under the said environment, and the vertical distance (mm) from the table surface of four corners was measured. The average value of each distance of the obtained four places was calculated, and this was taken as the curl amount (mm). The results are shown in Table 1.

[Test Example 2] <Measurement of heat shrinkage rate>
A test piece of 120 mm × 120 mm is cut out from the thermoplastic resin layer formed in the example or the EVA film of the comparative example, and a marked line is written on the inner side 10 mm from the vertical and horizontal ends on one side, and the initial marked line interval Was measured. Next, the test piece was placed in an oven maintained at 150 ° C. ± 2 ° C., left for 30 minutes, then removed, and left in a standard environment (23 ° C., 50% RH) for 24 hours. The dimensions were measured at the same positions as before the test, and the dimensional change rate (%) before and after the vertical and horizontal heat treatment was determined by the following formula. The results are shown in Table 1.
Dimensional change rate (%) = | (l ₁ -l ₀ ) / l ₀ | × 100
l ₁ : Dimensions after test (mm)
l ₀ : Initial marked line interval (mm)

[Test Example 3] <Adhesion test for sealing material>
In accordance with the method defined in Japanese Industrial Standards: JIS K6854-3: 1999, the adhesion of the protective sheets for solar cells obtained in Examples and Comparative Examples to the sealing material was evaluated. Specifically, it is as shown below.

The solar cell protective sheets obtained in Examples and Comparative Examples are laminated with a sealing material (EVA, manufactured by Sunvic, Ultrapearl, thickness: 400 μm) so that the thermoplastic resin layer is on the sealing material side. In addition, the sealing material and white plate tempered glass (thickness: 3 mm) were further laminated, and temporarily fixed by heating vacuum lamination using a vacuum laminator (Nisshinbo Co., Ltd., product name: PVL0505S). In the heat vacuum lamination, the vacuum state was set to 135 ° C. for 3 minutes, and the pressure state was set to 135 ° C. for 3 minutes.

Thereafter, the obtained laminate was heated at 150 ° C. for 30 minutes to crosslink the sealing material, thereby producing a pseudo solar cell module. Then, the solar cell protective sheet in the obtained pseudo solar cell module was cut with a width of 15 mm, and this was set as a test piece in a tensile tester (manufactured by A & D Co., Ltd., RTG-1225). The test piece was peeled 180 degrees at a peeling speed of 300 mm / min under the conditions of a temperature of 23 ° C. and a humidity of 50% RH, and the load at that time was measured as an adhesive force (N / 15 mm). In addition, if this adhesive force is 30 N / 15 mm or more, the adhesive force with respect to a sealing material is ensured. The results are shown in Table 1.

As can be seen from Table 1, the solar cell protective sheet of the example had a low thermal shrinkage rate of the thermoplastic resin layer, a small amount of curl in a low temperature environment, and a high adhesion to the sealing material. .

The protective sheet for solar cell according to the present invention is suitably used as a back sheet for a solar cell module, for example.

DESCRIPTION OF SYMBOLS 1,1A, 1B, 1C, 1D, 1E, 1F ... Protection sheet for solar cells 11 ... Base material 12 ... Adhesive layer 13A, 13B, 13C, 13D, 13E ... Thermoplastic resin layer 13F ... 1st thermoplastic resin Layer 131 ... First layer 132 ... Second layer 133 ... Third layer 14 ... Fluorine resin layer 15 ... Second thermoplastic resin layer 2 ... Solar battery cell 3 ... Sealing material 4 ... Glass plate 10 ... Solar battery module

Claims (18)

1. Homopolypropylene,
   A protective sheet for solar cells, comprising at least a thermoplastic resin layer containing random polypropylene and / or a thermoplastic elastomer.
2. A first layer containing random polypropylene and / or a thermoplastic elastomer;
   A protective sheet for a solar cell, comprising at least a thermoplastic resin layer including a second layer containing homopolypropylene laminated on the first layer.
3. The solar cell protective sheet according to claim 2, wherein the first layer further contains homopolypropylene.
4. The solar cell protective sheet according to claim 2 or 3, wherein the second layer further contains random polypropylene.
5. A first layer containing random polypropylene and / or a thermoplastic elastomer;
   A second layer containing homopolypropylene, laminated to the first layer;
   A protective sheet for solar cells, comprising at least a thermoplastic resin layer including a random polypropylene and / or a third layer containing a thermoplastic elastomer laminated on the second layer.
6. The solar cell protective sheet according to claim 5, wherein the first layer and / or the third layer further contain homopolypropylene.
7. The solar cell protective sheet according to claim 5 or 6, wherein the second layer further contains random polypropylene.
8. The second layer further contains at least one pigment selected from the group consisting of titanium oxide, talc, magnesium oxide, cerium oxide, barium sulfate, calcium carbonate, and carbon black. The protective sheet for solar cells as described in any one of these.
9. The solar cell protective sheet according to any one of claims 1 to 8, further comprising a base material.
10. The solar cell protective sheet according to claim 9, further comprising a fluororesin layer laminated on the base material.
11. The solar cell protective sheet according to any one of claims 2 to 4, further comprising a fluororesin layer laminated on the second layer.
12. The solar cell protective sheet according to claim 9 or 10, wherein the thermoplastic resin layer and the base material are laminated via an adhesive layer.
13. The solar cell protective sheet according to claim 9 or 10, wherein the thermoplastic resin layer is formed by extrusion coating on the substrate.
14. The thermoplastic resin layer and the base material are laminated via a second thermoplastic resin layer,
    The second thermoplastic resin layer is composed of ethylene and at least one selected from the group consisting of (meth) acrylic acid, (meth) acrylic acid ester, glycidyl (meth) acrylate, vinyl acetate, and maleic anhydride. The protective sheet for solar cells according to claim 9 or 10, comprising a copolymer as a main component.
15. The solar cell protective sheet according to claim 14, wherein the thermoplastic resin layer and the second thermoplastic resin layer are formed by extrusion coating on the substrate. .
16. The thermal shrinkage rate of the thermoplastic resin layer when the thermoplastic resin layer is heated at 150 ° C for 30 minutes is 1.0% or less, according to any one of claims 1 to 15, Protection sheet for solar cells.
17. The solar cell protective sheet according to any one of claims 1 to 16, wherein the thermoplastic resin layer is a layer adhered to a sealing material constituting a solar cell module.
18. A solar battery module comprising a solar battery cell, a sealing material for sealing the solar battery cell, and a protective sheet laminated on the sealing material,
    The protective sheet is a solar cell protective sheet according to claim 17,
    The said protection sheet is adhere | attached on the said sealing material through the said thermoplastic resin layer, The solar cell module characterized by the above-mentioned.

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