JP5621469B2 - Back surface protection sheet for solar cell module, back surface integrated sheet for solar cell module, and solar cell module - Google Patents

Description

  The present invention relates to a back surface protective sheet for a solar cell module, a back surface integrated sheet for a solar cell module, and a solar cell module.

  In recent years, solar cells as a clean energy source have attracted attention due to the growing awareness of environmental issues. Generally, a solar cell module that constitutes a solar cell has a configuration in which a transparent front substrate, a filler, a solar cell element, a filler, and a back surface protection sheet are sequentially laminated from the light receiving surface side, and sunlight is the solar cell element. It has a function to generate electricity by being incident on.

  Since the solar cell is often used outdoors due to its nature, the members constituting the solar cell module are required to have high durability. Especially, since the back surface protection sheet used for the solar cell module mainly protects the back surface of the solar cell module, it is required to have excellent mechanical strength and durability such as hydrolysis resistance.

  At present, as such a back surface protection sheet for a solar cell module, a plastic base material having excellent weather resistance or the like is most commonly used. For example, Patent Document 1 discloses a back surface protection sheet for a solar cell module that uses a composite film of a fluororesin film and a metal foil. Patent Document 2 discloses a back surface protection sheet for a solar cell module using a barrier film in which an inorganic oxide is deposited on a resin sheet instead of a metal foil.

JP 2000-174296 A JP 2001-44472 A

  The back surface protection sheet for solar cell modules as described in Patent Documents 1 and 2 is currently widely used, and its durability is about 20 to 25 years. At present, development of back surface protection sheets for solar cell modules having further excellent durability is being actively conducted.

  However, since the durability of the back surface protection sheet for solar cell modules is determined by various physical properties such as heat resistance, hydrolysis resistance, weather resistance, moisture resistance, etc., it is difficult to improve the durability. For this reason, the present condition is that the back surface protection sheet for solar cell modules excellent in durability is not obtained.

  This invention is made | formed in order to solve the above subjects, The objective is to provide the back surface protection sheet for solar cell modules excellent in long-term durability.

  In order to solve the above problems, the present inventors have made extensive studies, and as a result, a fluorine resin layer mainly composed of a fluorine resin, an unstretched polypropylene resin layer, and a polyethylene naphthalate resin layer. A solar cell having a laminated structure of four or more layers, including a structure in which a polyethylene naphthalate polycarbonate resin layer or a modified polyphenylene ether resin layer and a weather resistant resin layer mainly composed of a weather resistant resin are sequentially arranged If it is a back surface protection sheet for modules, it discovered that durability will be about 50 years (about 2 times compared with the past), and came to complete this invention. More specifically, the present invention provides the following.

  (1) A fluorine resin layer mainly composed of a fluorine resin, a first intermediate layer composed of an unstretched polypropylene resin layer, a polyethylene naphthalate resin layer, a polycarbonate resin layer, and a modified polyphenylene ether resin layer For a solar cell module having a laminated structure of four or more layers including a configuration in which a second intermediate layer composed of one or more selected layers and a weather resistant resin layer mainly composed of a weather resistant resin are sequentially arranged Back protection sheet.

  (2) The back surface protective sheet for a solar cell module according to (1), wherein the fluororesin is a copolymer of tetrafluoroethylene and ethylene, and the weather resistant resin is polyethylene.

  (3) The fluorine resin layer has a thickness of 15 μm or more and 75 μm or less, the unstretched polypropylene resin layer has a thickness of 20 μm or more and 180 μm or less, and the total thickness of the second intermediate layer is 20 μm or more and 180 μm or less, The back surface protection sheet for solar cell modules as described in (1) or (2) whose thickness of the said weather resistant resin layer is 15 micrometers or more and 180 micrometers or less.

  (4) Each layer of the laminated structure is laminated through an adhesive layer, and the adhesive layer is formed of a two-component adhesive containing a main agent and a curing agent, and the main agent is the following polyurethane diol (A) and a mixture of an aliphatic polycarbonate diol (B), and the polyurethane diol (A) includes at least an aliphatic polycarbonate diol (C), 1,6 hexanediol (D), and isophorone diisocyanate ( E), and the number average molecular weight of the polyurethane diol (A) is 7000 to 13000. The back protective sheet for solar cell module according to any one of (1) to (3) .

  (5) The back surface integration for solar cell modules in which the back surface protection sheet for solar cell modules according to any one of (1) to (4) and the filler layer on the back surface side are integrated in advance by a lamination process. Sheet.

  (6) A solar cell module using the back surface protective sheet for solar cell module according to any one of (1) to (4) or the back surface integrated sheet for solar cell module according to (5).

  According to this invention, since the back surface protection sheet for solar cell modules has a specific laminated structure of four or more layers, the durability is very high compared with the back surface protection sheet for conventional solar cell modules.

It is a figure which shows a solar cell module. It is a figure which shows an example of the back surface protection sheet for solar cell modules of this invention.

  Hereinafter, after briefly explaining the solar cell module, the back surface protective sheet for solar cell module and the back surface integrated sheet for solar cell module will be described in detail in this order. The present invention is not limited to the embodiments described below.

  First, the general solar cell module in which the back surface protection sheet for solar cell modules and the back surface integrated sheet for solar cell modules of this invention are used is demonstrated using FIG. In the solar cell module 1, for example, a transparent front substrate 2, a front filler layer 3, a solar cell element 4, a back filler layer 5, and a back surface protective sheet 6 are sequentially laminated from the light receiving surface side of incident light.

  The back surface protection sheet for solar cell modules of the present invention corresponds to the above back surface protection sheet 6, and the back surface integrated sheet for solar cell modules is obtained by integrating the back surface protection sheet 6 and the back surface filler layer 5. It hits. Details of these will be described later.

  Moreover, the back surface for solar cell modules of this invention in what integrated the solar cell module which uses the back surface protection sheet for solar cell modules of this invention for the back surface protection sheet 6, and the back surface protection sheet 6 and the back surface filler layer 5. The solar cell module using the integrated sheet corresponds to the solar cell module of the present invention.

  For example, the solar cell module is formed by sequentially laminating the members forming the respective layers and then integrating them by vacuum suction or the like, and then thermocompression-bonding the respective layers as an integrally formed body by a molding method such as a lamination method. Can be manufactured. Further, the solar cell module is obtained by forming a front filler layer and a back filler layer on each of the front surface side and the back surface side of the solar cell element by a molding method usually used in ordinary thermoplastic resins, for example, T-die extrusion molding. The solar cell element is sandwiched between the front filler layer and the rear filler layer, and then the transparent front substrate and the rear protective sheet are sequentially laminated, and then these are integrated by vacuum suction or the like and thermocompression bonded. You may manufacture by the method to do.

  In the solar cell module, conventionally known materials can be used without particular limitation for the transparent front substrate, the solar cell element, and the front filler layer. The solar cell module may include a member other than the above members.

<Back side protection sheet for solar cell module>
The back protective sheet for solar cell module of the present invention includes a fluorine resin layer mainly composed of a fluorine resin, a first intermediate layer composed of an unstretched polypropylene resin layer, a polyethylene naphthalate resin layer, and a polycarbonate resin. 4 or more layers including a structure in which a second intermediate layer composed of one or more layers selected from a layer or a modified polyphenylene ether-based resin layer and a weather resistant resin layer mainly composed of a weather resistant resin are sequentially disposed It has the laminated structure. For example, it has a structure as shown in FIG. FIG. 2 is a schematic view showing an example of the back surface protection sheet for solar cell module of the present invention. The back surface protection sheet 10 for solar cell module includes a fluorine resin layer 11, an unstretched polypropylene resin layer 12, and a polyethylene liner. It has a phthalate-based resin layer 13 and a weather-resistant resin layer 14, each layer is bonded with an adhesive, and an adhesive layer 15 is provided between each layer.

  Fluorine-based resin, unstretched polypropylene-based resin, polyethylene naphthalate-based resin, polycarbonate-based resin, modified polyphenylene ether-based resin, and weather-resistant resin all satisfy the physical properties required for the back protection sheet for solar cell modules, and Among the materials used for the back surface protection sheet for solar cell modules, it has very excellent hydrolysis resistance. Thus, the present invention is compared with the conventional back surface protection sheet for solar cell modules by combining materials having very excellent hydrolysis resistance and suitable physical properties as a back surface protection sheet for solar cell modules. And very excellent durability. The effect of the present invention is that an unstretched polypropylene resin layer, a polyethylene naphthalate resin layer, a polycarbonate resin layer, or a modified polyphenylene ether resin layer is provided between the fluorine resin layer and the weather resistant resin layer. It is played by preparing. Hereinafter, each layer will be described in more detail.

[Fluorine resin layer]
The fluorine-based resin layer contains a fluorine-based resin as a main component. Examples of the fluorine resin include polytetrafluoroethylene (PTFE), perfluoroalkoxy resin (PFA) composed of a copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether, and tetrafluoroethylene and hexafluoropropylene copolymer. (FEP), tetrafluoroethylene / perfluoroalkyl vinyl ether / hexafluoropropylene copolymer (EPE), tetrafluoroethylene / ethylene copolymer (ETFE), tetrafluoroethylene / propylene copolymer, Examples thereof include polychlorotrifluoroethylene resin (PCTFE), a copolymer of ethylene and chlorotrifluoroethylene (ECTFE), vinylidene fluoride resin (PVDF), and vinyl fluoride resin (PVF). Two or more of these resins may be used in combination. Among these, it is very preferable to use a copolymer of tetrafluoroethylene and ethylene (ETFE).

  Copolymer of tetrafluoroethylene and ethylene (ETFE) is excellent in mechanical or chemical strength, specifically, weather resistance, heat resistance, water resistance, light resistance, wind pressure resistance, yield resistance, chemical resistance It is a material that is excellent in various fastnesses such as durability and puncture resistance. Therefore, ETFE contributes to improving the durability of the back surface protection sheet for solar cell modules. In particular, ETFE is excellent in hydrolysis resistance among the materials used for the back surface protection sheet for solar cell modules.

  Fluorine resin layers include, for example, processability, heat resistance, light resistance, weather resistance, mechanical properties, dimensional stability, antioxidant properties, slip properties, mold release properties, flame retardancy, and resistance of fluorine resin layers. Various plastic compounding agents and additives, other resins, and the like can be added for the purpose of improving and modifying moldability, electrical characteristics, and the like. The addition amount of these additives and the like is not particularly limited, and can be arbitrarily added according to the purpose. Common additives include, for example, lubricants, crosslinking agents, antioxidants, UV absorbers, light stabilizers, fillers, lubricants, reinforcing fibers, reinforcing agents, antistatic agents, flame retardants, flame retardants, foaming Agents, fungicides, coloring additives, pigments, modifying resins and the like. Among these, the coloring additive is particularly preferably added to the material for the back protective sheet for solar cell modules. Hereinafter, the coloring additive will be described.

  Examples of the coloring additive include various dyes and pigments such as achromatic agents such as whitening agents and blackening agents, or chromatic colors such as red, orange, yellow, green, blue, purple, etc. One or more of these colorants can be used. Specifically, those described in JP-A-2004-230322 can be used. These coloring additives have the effect of imparting design properties, decorative properties, and the like that match the surrounding environment. Moreover, by using a whitening agent, in addition to the above-mentioned design and decoration, the light reflectivity for reusing the sunlight transmitted through the solar cell module by light reflection or light diffusion, An effect of imparting light diffusibility and the like to the solar cell module and an effect of reflecting or diffusing the sunlight reflected when the solar cell module is installed on a roof or the like are also obtained.

  The coloring additive is preferably contained in the fluorine-based resin layer in an amount of about 5 to 80% by mass.

  Examples of the fluororesin layer include those formed using an extrusion method, a cast molding method, a T-die method, a cutting method, an inflation method, and other film forming methods.

  The thickness of the fluororesin layer is not particularly limited, but is preferably about 10 to 75 μm, more preferably about 15 to 50 μm, and most preferably about 20 to 40 μm. When the thickness of the fluororesin layer is about 10 μm or more, sufficient weather resistance can be imparted to the back protective sheet for solar cell modules, and the thickness of the fluororesin layer is about 75 μm or less. Thereby, the film conveyance aptitude at the time of a lamination process can be provided. Further, the fluororesin layer to be formed may be a stretched film or an unstretched film.

The surface of the fluorine-based resin layer can be provided with a desired surface treatment layer in advance, if necessary, in order to improve close adhesion with other layers. The surface treatment layer may be, for example, a fluorine-based pretreatment such as corona discharge treatment, ozone treatment, plasma treatment using oxygen gas or nitrogen gas, glow discharge treatment, oxidation treatment using chemicals, etc. It can provide by providing arbitrarily on the surface of a resin layer.
In addition, a metal oxide film layer, a metal foil, or the like may be provided on the surface of the fluororesin layer in order to impart high moisture resistance and gas barrier properties. The metal oxide layer and the metal foil can be provided by a conventionally known method.

[First intermediate layer]
The unstretched polypropylene resin layer (first intermediate layer) includes a polypropylene resin. The polypropylene resin that can be used is not particularly limited, and general ones can be used. Specific examples of general polypropylene resins include various polypropylenes such as polypropylene homopolymer, propylene-ethylene copolymer, propylene-α olefin copolymer, metallocene catalyst polypropylene, and the like. In addition, the homopolymer or copolymer may contain other resin components as long as the effects of the present invention are not impaired. The unstretched polypropylene resin layer may contain other resins and general additives as long as the effects of the present invention are not impaired. Examples of the general additive include the same additives as those mentioned in the description of the fluororesin layer.

  The unstretched polypropylene-based resin layer is not deteriorated by hydrolysis, and is particularly excellent in hydrolysis resistance among the layers constituting the solar cell module back protective sheet of the present invention. Moreover, since an unstretched polypropylene resin layer is excellent also in water vapor | steam barrier property, it can fully suppress that a layer inside a non-stretched polypropylene resin layer deteriorates by hydrolysis. Moreover, since an unstretched polypropylene-type resin layer can be produced at low cost, the manufacturing cost of the back surface protection sheet for solar cell modules excellent in durability can be suppressed. The unstretched polypropylene-based resin layer tends to have slightly lower heat resistance and mechanical strength than other layers constituting the back surface protective sheet for solar cell module of the present invention. By having the phthalate-based resin layer, the polycarbonate-based resin layer, or the modified polyphenylene ether-based resin layer, it is possible to suppress a decrease in heat resistance and mechanical strength of the back surface protective sheet for solar cell modules.

  The unstretched polypropylene-based resin layer can be produced by using a conventionally known film forming method as with the fluorine-based resin layer.

  The thickness of the unstretched polypropylene resin layer is not particularly limited, but is preferably about 20 to 180 μm, more preferably about 30 to 140 μm, and most preferably about 50 to 120 μm. If the thickness of the unstretched polypropylene resin layer is about 20 μm or more, it is preferable because the hydrolysis resistance of the back surface protection sheet for solar cell modules is sufficiently increased, and if it is about 160 μm or less, the processability is satisfied. Is preferable.

  Further, the non-stretched polypropylene resin layer may be subjected to a surface treatment for improving adhesion with other layers in the same manner as the fluorine resin layer. Further, a metal oxide film and a metal foil may be provided on the unstretched polypropylene resin layer by a conventionally known method in order to further improve the barrier property and the like.

[Second intermediate layer]
The second intermediate layer is composed of one or more layers selected from a polyethylene naphthalate resin layer, a polycarbonate resin layer, and a modified polyphenylene ether resin layer. First, common points of these layers will be described, and then each layer will be described.

  These layers are all excellent in hydrolysis resistance, heat resistance, mechanical strength, and flame retardancy. By combining these layers with a fluorine-based resin layer, an unstretched polypropylene-based resin layer, and a weather-resistant resin layer, which will be described later, a solar cell module back protection sheet having excellent durability is obtained.

  The production of these resin layers can be carried out by using a conventionally known film forming method in the same manner as the fluorine resin layer.

  The thickness of these layers is not particularly limited, and the preferred thickness is slightly different depending on the type of the layer, etc., and even if any layer is adopted, it is preferably about 20 to 180 μm, more preferably about 30 to 160 μm, and more preferably about 40 Most preferred is ˜140 μm. If the thickness of the layer is about 20 μm or more, it is preferable because the necessary mechanical strength can be obtained, and if it is about 180 μm or less, it is preferable because the processability is satisfied.

  In addition, these layers may be subjected to a surface treatment for improving adhesion with other layers in the same manner as the fluororesin layer. In addition, a metal oxide film and a metal foil may be provided on these layers by a conventionally known method in order to improve barrier properties.

  Next, each layer will be described. Hereinafter, the polyethylene naphthalate resin layer, the polycarbonate resin layer, and the modified polyphenylene ether resin layer will be described in this order.

  First, the polyethylene naphthalate resin layer will be described. The polyethylene naphthalate resin contained in the polyethylene naphthalate resin layer is preferably composed mainly of 2,6-naphthalenedicarboxylic acid, and a single resin of polyethylene naphthalate resin can be used. In addition, a part of at least one of the acid component (2,6-naphthalenedicarboxylic acid) and the glycol component (ethylene glycol) constituting the polyethylene naphthalate is added to the other component within a range not significantly impairing the effects of the present invention. Copolyesters substituted with an acid component or a glycol component can also be used. Further, the polyethylene naphthalate resin may contain other resin components other than the acid component and the glycol component as long as the effects of the present invention are not impaired. Further, the polyethylene naphthalate resin layer may contain other resins and general additives as long as the effects of the present invention are not impaired. Examples of the general additive include the same additives as those mentioned in the description of the fluororesin layer.

  The polyethylene naphthalate-based resin layer is excellent in hydrolysis resistance, heat resistance, mechanical strength, and flame resistance, and also in dimensional stability. As a result of excellent dimensional stability, the use of a polyethylene naphthalate resin layer facilitates the production of a solar cell module as compared to the case of using a modified polyphenylene ether resin layer. Moreover, when a polyethylene naphthalate resin layer is employed, the durability of the back surface protective sheet for solar cell module can be further improved as compared with the case where a polycarbonate resin layer is employed.

  Next, the polycarbonate resin layer will be described. The polycarbonate-based resin is a linear polymer having a carbonate ester bond in the main chain, and is generally produced from bisphenol A as a raw material. The polycarbonate-based resin is a resin having polycarbonate as a main component, but may contain other resin components. The polycarbonate-based resin layer may contain other resins and general additives as long as the effects of the present invention are not impaired. Examples of the general additive include the same additives as those mentioned in the description of the fluororesin layer.

  The polycarbonate-based resin has physical properties required for a material used for the back surface protection sheet for a solar cell module, and particularly has very high hydrolysis resistance, dimensional stability, heat resistance, and flame resistance. Since the polycarbonate-based resin has polycarbonate as a main component, it has the properties of the polycarbonate. By using such a polycarbonate-based resin in combination with the above-mentioned fluorine-based resin and a weather-resistant resin described later, the durability of the back surface protective sheet for solar cell modules is increased. Since polycarbonate has excellent dimensional stability, the use of a polycarbonate resin layer facilitates the production of a solar cell module as compared to the use of a modified polyphenylene ether resin layer described later. Polycarbonate is cheaper than the above-mentioned polyethylene naphthalate and modified polyphenylene ether.

  Next, the modified polyphenylene ether resin layer will be described. The modified polyphenylene ether resin layer is a layer mainly composed of modified polyphenylene ether. The modified polyphenylene ether is a general term for a synthetic resin polymer alloy belonging to a thermoplastic resin mainly composed of polyphenylene ether (PPE) having an aromatic polyether structure. The thermoplastic resin to be mixed with the polyphenylene ether is not particularly limited, but it is preferable to use a polystyrene resin. Modification by mixing polyphenylene ether and a thermoplastic resin is preferable from the viewpoint of easy production, but may be modification by copolymerizing a phenolic monomer with another monomer.

  Examples of the polyphenylene ether include poly (2,6-dimethylphenylene-1,4-ether), poly (2-methyl-6-ethylphenylene-1,4-ether), and poly (2,6-diethylphenylene). 1,4-ether), poly (2-methyl-6-n-propylphenylene-1,4-ether), poly (2-methyl-6-n-butylphenylene-1,4-ether), poly (2 -Methyl-6-chlorophenylene-1,4-ether), poly (2-methyl-6-bromophenylene-1,4-ether), poly (2-ethyl-6-chlorophenylene-1,4-ether) Etc. These may be used alone or in combination of two or more.

  Examples of the polystyrene resin include polystyrene, styrene-α-methylstyrene copolymer, and styrene-butadiene copolymer represented by high impact polystyrene. These may be used alone or in combination of two or more.

  The modified polyphenylene ether resin layer may contain a resin other than the modified polyphenylene ether resin. Further, the modified polyphenylene ether resin layer may contain various additives such as those contained in the fluorine resin layer.

  The modified polyphenylene ether has physical properties required for the material used for the back surface protection sheet for solar cell modules, and particularly has very high hydrolysis resistance, heat resistance, and flame retardancy. Since the modified polyphenylene ether-based resin layer is mainly composed of modified polyphenylene ether, it has the properties of the modified polyphenylene ether. By using such a polyphenylene-based resin in combination with the unstretched polypropylene-based resin layer or the like, the durability of the back surface protective sheet for solar cell modules becomes very high. When the modified polyphenylene ether-based resin layer is employed, durability is further increased as compared with the case where the polycarbonate-based resin layer is employed.

[Weather-resistant resin layer]
As the weather resistant resin layer, the same weather resistant resin as described in JP-A-2002-83988 can be used. The weather resistant resin layer is a layer in contact with the filler. For this reason, selection of the material to be used can be performed in consideration of, for example, adhesion to the filler. In particular, it is very preferable to use an olefin-based filler as the filler and polyethylene or polypropylene as the weather resistant resin. Polyethylene and polypropylene have high adhesion to olefin-based fillers, and the combination of these materials contributes to improving the durability of the back protective sheet for solar cell modules. The weather resistant resin layer may contain a resin other than the weather resistant resin. Moreover, you may make a weather resistant resin layer contain various additives which are contained in a fluorine resin layer.

  The polyethylene is not particularly limited, and any of conventionally known high-density polyethylene, low-density polyethylene, and linear low-density polyethylene can be used.

  When polypropylene is used for the weather resistant resin layer, it is preferably an unstretched polypropylene resin layer, and the unstretched polypropylene resin layer is the same as described above.

  In particular, the weather resistant resin layer preferably contains an additive for coloring in the same manner as the fluorine resin layer. Examples of the coloring additive that can be contained are the same as those described above. The use of a whitening agent is particularly preferable.

  The weather-resistant resin layer can be produced by using a conventionally known film forming method in the same manner as the fluorine resin layer.

  The thickness of the weather resistant resin layer is not particularly limited, but is preferably about 15 to 180 μm, more preferably about 20 to 170 μm, and most preferably about 25 to 160 μm. If the thickness of the weather-resistant resin layer is about 15 μm or more, it is preferable because necessary mechanical strength is obtained, and if it is about 180 μm or less, it is preferable because processability is satisfied.

  In addition, the weather resistant resin layer may be subjected to a surface treatment for improving adhesion to other layers in the same manner as the fluorine resin layer. In addition, a metal oxide film and a metal foil may be provided on the weather resistant resin layer by a conventionally known method in order to improve barrier properties and the like.

[Other resin layers]
If the back surface protection sheet for solar cell modules of this invention is four or more layers including the structure by which a fluorine-type resin layer, a polycarbonate-type resin layer or a modified polyphenylene ether-type resin layer, and a weather-resistant resin layer are arrange | positioned one by one. In addition, other layers may be further included as long as the effects of the present invention are not impaired. The components, thicknesses, and the like contained in the other resin layers can be appropriately changed, and the production method of the other resin layers is not particularly limited, and can be produced by a conventionally known method in the same manner as the essential layers described above. .

[Method for producing back surface protection sheet for solar cell module]
The manufacturing method of the back surface protection sheet for solar cell modules of this invention is not specifically limited, For example, an adhesive bond layer is provided between each layer, and it can manufacture by dry lamination processing.

  Examples of adhesives that can be used for the adhesive layer include polyvinyl acetate adhesives, polyacrylate adhesives, cyanoacrylate adhesives, ethylene copolymer adhesives, polyolefin adhesives, and cellulose adhesives. Adhesive, polyester adhesive, polyamide adhesive, polyimide adhesive, amino resin adhesive, phenol resin adhesive, epoxy adhesive, polyurethane adhesive, reactive (meth) acrylic Examples thereof include system adhesives, rubber adhesives, silicone adhesives, and inorganic adhesives. These adhesives can be used in a conventionally known composition system and method of use. In the present invention, it is preferable to provide the following adhesive layer. This is because the following adhesive layer is excellent in adhesion and weather resistance.

[Adhesive layer]
In the present invention, a suitable adhesive layer is formed using a two-component adhesive. The two-component adhesive is a type of adhesive in which a main agent and a curing agent are mixed immediately before use. Hereinafter, the main agent, the curing agent, the solvent and the like constituting the two-component adhesive will be described.

[Main agent]
The main component of the adhesive includes a mixture of polyurethane diol (A) and aliphatic polycarbonate diol (B). The (A) component and (B) component contained in this mixture react with the curing agent having an isocyanate group to constitute an adhesive layer.

  The main component polyurethane diol (A) has a urethane structure as its repeating unit and has hydroxyl groups at both ends. (A) The number average molecular weight of a component is 7000-13000. When it is 7000 or more, it is preferable because the reactivity with the curing agent is good, and when it is 13000 or less, dissolution in a solvent is improved.

  The polyurethane diol (A) is obtained by reacting an aliphatic polycarbonate diol (C), 1,6 hexanediol (D), and isophorone diisocyanate (E). By using this component (A), the adhesiveness and weather resistance of the adhesive layer are improved. Hereinafter, the components (C) to (E) will be described.

  The aliphatic polycarbonate diol (C) has a carbonate structure as a repeating unit and has hydroxyl groups at both ends. The hydroxyl groups at both ends react with an isocyanate group.

  The manufacturing method of aliphatic polycarbonate diol (C) is not specifically limited, A conventionally well-known method is employable. For example, it can be produced using alkylene carbonate and diol as raw materials. In addition, a commercial item may be sufficient as (C) component.

  The number average molecular weight of the aliphatic polycarbonate diol (C) is preferably about 1000 to 2000. When it is 1000 or more, it is preferable because a curing reaction with diisocyanate easily occurs, and when it is 2000 or less, solubility in a solvent as an adhesive component is improved. The number average molecular weight can be adjusted by controlling the reaction rate and the like.

  The 1,6 hexanediol (D) component is liquid at room temperature and can be dissolved in a solvent as an adhesive component. It is preferable that the compounding quantity of (D) component is about 5-15 mass parts with respect to 100 mass parts of aliphatic polycarbonate diol (C).

  A polyester diol (H) such as an aromatic polyester diol can be used together with 1,6 hexanediol (D). Component (H) has an excellent cure for polyurethane diol (A) obtained by reacting with isophorone diisocyanate (E) because its basic skeleton can be an ester with a carboxylic acid having a bulky aromatic ring. Speed and cohesion can be imparted. In addition, (H) component can be manufactured by a conventionally well-known method.

  It is preferable that the compounding quantity of polyester diol (H) is about 50-100 mass parts with respect to 100 mass parts of aliphatic polycarbonate diol (C).

  The number average molecular weight of the polyester diol (H) is preferably about 3000 to 4000. When it is 3000 or more, it is preferable because of high durability, and when it is 4000 or less, it is preferable because processability is good.

  Isophorone diisocyanate (E) reacts with a hydroxyl group of the aliphatic polycarbonate diol (C), 1,6 hexanediol (D) or polyester diol (H) to form a polyurethane diol (A) as a main component.

  The above-described aliphatic polycarbonate diol (C), aliphatic diol (D), and isophorone diisocyanate (E) are dissolved in a solvent, mixed and heated to reflux to react with the polyurethane diol (A) as the main component. A solution can be obtained. In addition, the solvent to be used should just be what can dissolve each component and does not react with a solvent.

  The aliphatic polycarbonate diol (B), which is the main component, reacts with the curing agent component having an isocyanate group. As the component (B), the same aliphatic polycarbonate diol (C) as used in the production of the polyurethane diol (A) can be used.

  The mass ratio of the polyurethane diol (A) to the aliphatic polycarbonate diol (B) in the mixture is approximately 10 to 20 parts by mass of the aliphatic polycarbonate diol (B) with respect to 100 parts by mass of the polyurethane diol (A). preferable.

  In addition to the above-mentioned essential components, a tackifier, a stabilizer, a filler, a plasticizer, a softening point improver, a catalyst, and the like can be added to the main agent as an additive as necessary.

[Curing agent]
The adhesive curing agent is mainly composed of a polyisocyanate compound. A conventionally well-known thing can be used as a polyisocyanate compound. In this invention, a hardening | curing agent contains the mixture of the nurate body (F) of isophorone diisocyanate, and the hexamethylene diisocyanate type bifunctional polyurethane diisocyanate (G), and these mass ratios are about (F) :( G) = 30: What is 70-50: 50 is preferable.

[solvent]
It is preferable to add a solvent component such as a carboxylic acid ester to the main agent and the curing agent, which are the adhesive components, in order to obtain good coatability and handling suitability. In addition, although the said adhesive agent is comprised as a 2 liquid agent of a main ingredient and a hardening | curing agent, the solvent component used with a main ingredient and the solvent component used with a hardening | curing agent are each selected independently, and may be the same or different. .

[Other ingredients]
In addition to the main agent, curing agent and solvent, the adhesive component is mixed with silane coupling agents, tackifiers, stabilizers, fillers, plasticizers, softening point improvers, catalysts, etc. as additives. can do. From the viewpoint of improving the durability of the back surface protective sheet for a solar cell module, it is preferable to use a silane coupling agent. It is preferable that the usage-amount of a silane coupling agent is about 1-3 mass parts with respect to 100 mass parts in total of a main ingredient and a hardening | curing agent.

<Back side integrated sheet for solar cell module>
The back surface integrated sheet for solar cell modules of the present invention is obtained by integrating the back surface protective sheet for solar cell modules of the present invention and a back surface filler layer. If laminated in advance to form an integrated sheet, there are advantages in that the man-hours for manufacturing the solar cell module can be reduced and the transportation and management of the members can be simplified. First, the back filler layer will be described.

[Back filler layer]
The material used for the back surface filler layer is not particularly limited, and a known resin that is used as the filler layer of the solar cell module can be preferably used. Examples of such a resin include EVA (ethylene-vinyl acetate copolymer), polyvinyl butyral, ethylene ionomer, and a copolymer obtained by copolymerizing an α-olefin and an ethylenically unsaturated silane compound as a comonomer ( Olefin-based filler) and the like.

  Among the above resins, a silane copolymer obtained by copolymerizing an α-olefin and an ethylenically unsaturated silane compound as a comonomer can be preferably used. By using such a resin, sufficient adhesion to other members such as solar cell elements can be obtained. In particular, adhesion is strong when the layer in contact with the back surface filler layer of the back surface protective sheet for solar cell module of the present invention is a weather resistant resin layer mainly composed of polyethylene. The copolymer obtained by copolymerizing an α-olefin and an ethylenically unsaturated silane compound as a comonomer indicates, for example, a copolymer described in JP-A-2003-46105.

[Manufacturing method of back filler layer]
When using the filler sheet consisting of the back surface filler layer in the production of the back surface integrated sheet for the solar cell module of the present invention described later, the filler sheet is prepared in advance by the following method.

  The filler sheet is produced, for example, by various molding methods such as injection molding, extrusion molding, hollow molding, compression molding, and rotational molding, which are usually used in ordinary thermoplastic resins.

  The filler sheet may be multilayer, and the multilayer filler sheet can be produced using, for example, a conventionally known T-die multilayer coextrusion method.

[Method for producing back surface integrated sheet for solar cell module]
The manufacturing method of the back surface integrated sheet for the solar cell module is not particularly limited, and the modified olefin system is used between the dry laminating method, the filler sheet, and the back surface protective sheet for the solar cell module of the present invention. The extrusion simultaneous lamination method in which an adhesive resin such as an adhesive resin is melt-extruded and sand-laminated, and the solar cell module back surface protective sheet and back surface filler sheet of the present invention are pressed in the thickness direction at the same time, and the solar of the present invention By heating from the back surface protection sheet side for the battery module, the thermal lamination method of softening or melting the side facing the back surface protection sheet for the solar cell module of the present invention, filling the back surface protection sheet for the solar cell module of the present invention, Examples include a melt filler extrusion method in which the resin composition constituting the material sheet is melt extruded. .

  Among these manufacturing methods, from the viewpoint of suppressing warpage, a thermal lamination method, a dry laminating method, and a molten filler extruding method that can reduce the internal stress of the back surface filler layer at the time of lamination are preferable. The melt filler extrusion method is most preferred.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to a following example.

<Example 1>
A back surface protection sheet for a solar cell module having a four-layer structure in which a fluorine-based resin layer, an unstretched polypropylene-based resin layer, a polyethylene naphthalate-based resin layer, and a weather-resistant resin layer are sequentially laminated is manufactured by the following method. did.

[Fluorine resin layer]
A 25 μm ETFE sheet (manufactured by Asahi Glass Co., Ltd., trade name “Aflex”) was used as the fluorine resin layer.

[Unstretched polypropylene resin layer]
80 μm unstretched polypropylene resin sheet (product name “Art Ply”, manufactured by Mitsubishi Plastics)

[Polyethylene naphthalate resin layer]
As the polyethylene naphthalate resin layer, a 50 μm polyethylene naphthalate resin sheet (trade name “Teonex” manufactured by Teijin DuPont) was used.

[Preparation of weather-resistant resin layer]
80 parts by mass of linear low density polyethylene (density 0.920 g / cm ³ , manufactured by Sumitomo Chemical Co., Ltd., trade name “Sumikasen-L”), titanium oxide (made by Ishihara Sangyo Co., Ltd., trade name “Taipaque”) as a whitening agent ) Was added in an amount of 20 parts by mass to prepare a polyethylene-based resin composition, and the polyethylene-based resin composition was extruded with an extruder to prepare a 140 μm weather-resistant resin layer.

[Manufacture of adhesives]
First, preparation of the main agent will be described. The main agent is a mixture of polyurethane diol (A) and aliphatic polycarbonate diol (B). Hereinafter, the polyurethane diol (A) and the aliphatic polycarbonate diol (B) will be described in this order.

Aliphatic polycarbonate diol (C) having a number average molecular weight of 1000 (trade name “Duranol T5651” manufactured by Asahi Kasei Chemicals Corporation) (100 parts by mass) and 1,6-hexanediol (D) in a flask equipped with a stirrer under a nitrogen atmosphere , Isophorone diisocyanate (E), polyester diol (H), and ethyl acetate were added, and the mixture was heated to reflux in the infrared absorption spectrum until the absorption of 2270 cm ⁻¹ isocyanate disappeared, and a 50% by mass solution of polyurethane diol (A) was obtained. Obtained. The number average molecular weight of the obtained resin was about 8,000.

  As the aliphatic polycarbonate diol (B), an aliphatic polycarbonate diol having a number average molecular weight of 1000 (manufactured by Asahi Kasei Chemicals Corporation, trade name “Duranol T5651”) was used.

  The aliphatic polycarbonate diol (B) was mixed with 100 parts by mass of the polyurethane diol (A). Ethyl acetate was further added to the mixture so that the solid content was 50% by mass. This mixture was used as the main agent.

  Next, preparation of the curing agent will be described. Isophorone diisocyanate nurate (F) and bifunctional HDI urethane-based isocyanate (G) ("Duranate D101" manufactured by Asahi Kasei Chemicals Corporation) were mixed. Ethyl acetate was further added to the mixture so that the solid content was 50% by mass. This mixture was used as a curing agent.

  Next, the silane coupling agent will be described. As a silane coupling agent, 3-glycidoxypropyltrimethoxysilane was used. A silane coupling agent and ethyl acetate were mixed so that the solid content was 50% by mass. This mixture was used as a silane coupling agent.

  A curing agent and a silane coupling agent were mixed with 100 parts by mass of the main agent. The mixture obtained here corresponds to the adhesive.

[Preparation of back surface protection sheet for solar cell module]
These layers were joined by the following dry laminating process and aged at 40 ° C. for 5 days to prepare a back protective sheet for a solar cell module of Example 1.

By a gravure roll coating method ETFE resin layer facing the unstretched polypropylene resin layer, was coated so that the adhesive mixture to 1 m ² per 4.0~6.0g / ^{m 2} (dry) adhesive An agent layer was formed. Thereafter, an unstretched polypropylene resin layer was laminated on the adhesive layer, and a fluorine resin layer and an unstretched polypropylene resin layer were laminated. The non-stretched polypropylene resin layer and the polyethylene naphthalate resin layer and the polyethylene naphthalate resin layer and the weather resistant resin layer were laminated in the same manner.

<Example 2>
A protective sheet for a solar cell module of Example 2 in the same manner as in Example 1 except that an 80 μm unstretched polypropylene resin sheet containing 10% by mass of titanium oxide as a whitening agent was used as the weather resistant resin layer. Manufactured.

<Example 3>
Instead of the adhesive produced by the above method, an adhesive mainly composed of polyester urethane (made by Mitsui Chemicals, trade name “Takelac”) and a curing agent (made by Mitsui Chemicals, trade name “Takenate”) are used. The back surface protection sheet for the solar cell module of Example 3 was produced in the same manner as in Example 1 except that an adhesive mixed solution obtained by mixing “)” was used.

<Comparative Example 1>
Instead of the unstretched polypropylene resin layer and the polyethylene naphthalate resin layer, a polyethylene terephthalate resin layer (PET) having the same thickness as the total thickness of these layers was provided between the fluorine resin layer and the weather resistant resin layer. Except for the above, a back protective sheet for a solar cell module of Comparative Example 1 was produced in the same manner as in Example 1.

<Durability evaluation>
The durability of the back surface protection sheet for solar cell modules of 150 mm length and 10 mm width examples and comparative examples was evaluated by a method according to the international standard IEC 61730 for solar cell modules. The sample was left in an environmental test machine set at a temperature of 85 ° C. and a humidity of 85% RH for 8000 hours. The back surface protection sheet for solar cell modules was taken out, the longitudinal breaking strength was measured 5 times, and the average value was obtained. A value obtained by dividing the average value by the measured value of the breaking strength before standing was defined as the breaking strength retention rate (%), and evaluated according to the following criteria.
Breaking strength retention rate (%)
= (Breaking strength after 8000 hours) / (initial breaking strength) × 100
◎: Breaking strength retention 80% or more ○: Breaking strength retention 50% or more and less than 80% ×: Breaking strength retention 5% or more but less than 50%

In the case of the evaluations “「 ”and“ ◯ ”, it is presumed that the outdoor durability of 50 years or more is expected because the function necessary for maintaining the performance of the solar cell module is maintained. In the case of the evaluation of “x”, it is estimated that there is only outdoor durability of about 20 years because the protection function from the external environment is reduced and the efficiency of the solar cell module is reduced.

  As is clear from the above evaluation results, a fluorine resin layer mainly composed of a fluorine resin, a first intermediate layer, a second intermediate layer, a weather resistant resin layer mainly composed of a weather resistant resin, The back surface protection sheet for solar cell modules having a laminated structure in which are sequentially arranged has very high durability.

  Confirmation that durability is further enhanced by using an adhesive for producing a back surface protection sheet for a solar cell module, which includes a mixture of polyurethane diol (A) and aliphatic polycarbonate diol (B). It was done.

DESCRIPTION OF SYMBOLS 1 Solar cell module 2 Transparent front substrate 3 Front filler layer 4 Solar cell element 5 Back filler layer 6 Back surface protection sheet 10 Back surface protection sheet 11 for solar cell modules Fluorine resin layer 12 Unstretched polypropylene resin layer 13 Polyethylene naphthalate Resin layer 14 Weather resistant resin layer 15 Adhesive layer

Claims (6)

A fluorine resin layer mainly composed of a fluorine resin;
A first intermediate layer composed of an unstretched polypropylene-based resin layer;
A second intermediate layer composed of one or more layers selected from a polyethylene naphthalate resin layer, a polycarbonate resin layer, and a modified polyphenylene ether resin layer;
A weather-resistant resin layer composed mainly of weatherable resins, but have a four or more layers of a laminated structure including a structure sequentially arranged,
Each layer of the laminated structure is laminated via an adhesive layer,
The adhesive layer is formed of a two-component adhesive containing a main agent and a curing agent,
The main agent includes a mixture of the following polyurethane diol (A) and aliphatic polycarbonate diol (B),
The polyurethane diol (A) is a reaction product starting from at least an aliphatic polycarbonate diol (C), 1,6 hexanediol (D), and isophorone diisocyanate (E).
The number average molecular weight of the said polyurethane diol (A) is a back surface protection sheet for solar cell modules which is 7000-13000 . The fluororesin is a copolymer of tetrafluoroethylene and ethylene,
The back surface protection sheet for solar cell modules according to claim 1, wherein the weather resistant resin is polyethylene. The fluorine resin layer has a thickness of 15 μm or more and 75 μm or less,
The thickness of the unstretched polypropylene resin layer is 20 μm or more and 180 μm or less,
The total thickness of the second intermediate layer is 20 μm or more and 180 μm or less;
The back surface protection sheet for solar cell modules according to claim 1 or 2, wherein the weather-resistant resin layer has a thickness of 15 µm or more and 180 µm or less. The back surface integrated sheet for solar cell modules by which the back surface protection sheet for solar cell modules in any one of Claim 1 to 3 and the filler layer of the back surface side were integrated previously by the lamination process. The solar cell module using the back surface protection sheet for solar cell modules in any one of Claim 1 to 3 . The solar cell module which uses the back surface integration sheet for solar cell modules of Claim 4 .

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