JP2007103738A - Solar battery sealing member, solar battery sealing sheet, and solar battery module using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solar battery sealing member employing a copolymer of ethylene/α-olefin that defines a guideline for obtaining a desired physical properties without necessarily a crosslink; is excellent in heat resistance, transparency, flexibility and process stability; and is capable of omitting the crosslink as required to improve productivity. <P>SOLUTION: The solar battery sealing member contains 70 to 5 pts.wt. of crystalline polypropylene resin (A), and 30 to 95 pts.wt. of a copolymer of ethylene/α-olefin (B) with the density of 0.85 to 0.87 (total of (A) and (B) is 100 pts.wt.). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a solar cell encapsulant used for shielding a solar cell element from the outside air. More specifically, the present invention is excellent in properties such as transparency and flexibility, and is excellent in process stability. The present invention relates to a solar cell encapsulant that is advantageous when manufacturing a solar cell module.

  The present invention further relates to a solar cell sealing sheet using such a solar cell sealing material, and a solar cell module using the sealing material and / or the sealing sheet.

  As global environmental problems, energy problems, and the like become more serious, solar cells are attracting attention as an energy source that is clean and free from depletion. When a solar cell is used outdoors such as a roof portion of a building, it is generally used in the form of a solar cell module.

  A solar cell module is usually structured such that solar cells formed of polycrystalline silicon or the like are sandwiched and laminated with a solar cell sealing material made of a soft transparent resin, and both front and back surfaces are covered with a protective sheet for a solar cell module. ing. That is, a typical solar cell module is a solar cell module protective sheet (surface protective sheet) / solar cell sealing sheet / solar cell / solar cell sealing sheet / solar cell module protective sheet (back surface protective sheet). It has a laminated structure. As a result, the solar cell module has weather resistance and is suitable for outdoor use such as a roof portion of a building.

  Conventionally, as a material (solar cell sealing material) constituting a solar cell sealing sheet, ethylene-vinyl acetate copolymer (EVA) has been widely used due to its transparency, flexibility, etc. (for example, (See Patent Document 1). When using an ethylene-vinyl acetate copolymer for a solar cell encapsulant, it is common to perform a crosslinking treatment in order to give sufficient heat resistance. Since a long time is required, it has been a cause of lowering the production speed and production efficiency of the solar cell module. In addition, there is a concern that components such as acetic acid gas generated by the decomposition of EVA may affect the solar cell element.

One of the measures for solving the above technical problem is to use an ethylene / α-olefin copolymer for at least a part of the solar cell encapsulant, and also for ethylene / α- There is also a proposal for a solar cell encapsulant using an olefin copolymer (see Patent Document 2). However, Patent Document 2 discloses any specifics on the usage form of the ethylene / α-olefin copolymer for obtaining preferable properties (heat resistance, transparency, flexibility, process stability resistance, etc.) as a sealing material. It also does not disclose general guidelines. This is presumably because the technique disclosed in Patent Document 2 is premised on the crosslinking treatment, and is intended to achieve desired physical properties together with the crosslinking treatment.
JP-A-8-283696 JP 2000-091611 A

    In view of the above background, the object of the present invention is to clarify guidelines for obtaining desired physical properties (without necessarily crosslinking) in a solar cell sealing material using an ethylene / α-olefin copolymer, To provide a solar cell encapsulant that is excellent in various properties such as heat resistance, transparency, flexibility, and process stability, and that can improve productivity by omitting cross-linking as necessary. .

As a result of intensive studies, the present inventors have used an ethylene / α-olefin copolymer in a specific density range in combination with a crystalline polypropylene resin at a specific weight ratio, whereby heat resistance, transparency, The present inventors have found that a solar cell encapsulant that is excellent in flexibility and process stability and that can improve the productivity by omitting cross-linking as necessary can be obtained.
That is, the present invention
(1) Crystalline polypropylene resin (A) 70 to 5 parts by weight, and ethylene / α-olefin copolymer (B) having a density of 0.85 to 0.87 (B) 30 to 95 parts by weight ((A) And the sum of (B) is 100 parts by weight.).

Hereinafter, (2) to (8) are each a preferred embodiment of the present invention.
(2) The solar cell sealing material according to (1), wherein the ethylene / α-olefin copolymer (B) has a structural unit derived from an α-olefin having 4 or more carbon atoms.
(3) The ethylene / α-olefin copolymer (B) contains 30 to 70 mol% of structural units derived from ethylene and 70 to 30 mol in total of structural units derived from an α-olefin having 4 or more carbon atoms. %, The solar cell encapsulant according to (2) above.
(4) The solar cell encapsulant according to (1), which has two or more glass transition point peaks measured by a temperature change of loss tangent (tan δ).
(5) The solar cell encapsulating material according to any one of (1) to (4), further comprising a silane coupling agent (C).
(6) The solar cell sealing sheet obtained using the solar cell sealing material of any one of said (1)-(5).
(7) The sun obtained by using the solar cell encapsulant described in any one of (1) to (5) above and / or the solar cell encapsulating sheet described in (6) above. battery.
(8) A power generation facility obtained using the solar cell module according to (7).

  ADVANTAGE OF THE INVENTION According to this invention, the solar cell sealing material excellent in heat resistance, transparency, a softness | flexibility, and process stability can be obtained. This solar cell encapsulant can improve productivity by omitting cross-linking as necessary, and has excellent economic efficiency in addition to the above-described excellent characteristics.

  Hereinafter, the present invention will be described in detail.

Crystalline polypropylene resin (A)
Here, “crystallinity” means that the crystallinity is 30% or more. The crystallinity can be determined by a conventional wide-angle X-ray analysis.

  The crystalline polypropylene resin (A) is not particularly limited as long as it satisfies the above “crystallinity” conditions and has a structural unit derived from propylene.

Examples thereof include a propylene homopolymer or a copolymer of propylene and at least one α-olefin having 2 to 20 carbon atoms other than propylene. Here, the α-olefin having 2 to 20 carbon atoms other than propylene includes ethylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, Examples thereof include 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicocene, and the like, and ethylene or α-olefin having 4 to 10 carbon atoms is preferable. These α-olefins may be used alone or in combination of two or more. These α-olefins may form a random copolymer with propylene or a block copolymer.
The structural unit derived from these α-olefins may or may not be contained in the polypropylene in a proportion of usually 20 mol% or less, preferably 15 mol% or less. For example, polypropylene homopolymer, propylene / ethylene block copolymer having an ethylene content of 20 to 70% by weight, propylene / ethylene random copolymer having an ethylene content of 0.5 to 12% by weight, and an ethylene content of 0.5 to 12 A propylene / ethylene / α-olefin terpolymer having an α-olefin content of 0.5 to 20 wt% such as wt% and butene-1 can be preferably used.

  The crystalline polypropylene resin (A) has a melt flow rate (MFR) measured at 230 ° C. and a load of 2.16 kg in accordance with ASTM D 1238 at 0.001 to 500 g / 10 minutes, preferably 0.01 to It is desirable to be in the range of 50 g / 10 minutes.

  Melting | fusing point observed with the differential scanning calorimeter of a crystalline polypropylene resin (A) is 110 degreeC or more normally, Preferably it is 120-165 degreeC, More preferably, it is 110-150 degreeC.

  As the crystalline polypropylene resin (A), either an isotactic structure or a syndiotactic structure can be used, but the isotactic structure is preferable in view of heat resistance. In addition, a plurality of crystalline polypropylene resins (A) can be used in combination as necessary, and for example, two or more components having different melting points and rigidity can be used.

  As the crystalline polypropylene resin (A), homopolypropylene excellent in heat resistance (usually known is a copolymer having a copolymer component other than propylene of 3 mol% or less is preferable), a block excellent in balance between heat resistance and flexibility. Polypropylene (usually a known material having a normal decane eluting rubber component of 3 to 30 wt% is preferable), and random polypropylene excellent in balance between flexibility and transparency (usually a melting peak measured by a differential scanning calorimeter DSC is 100 It is possible to select or use a known one having a temperature of at least 0 ° C., preferably in the range of 110 ° C. to 150 ° C., so that the desired physical properties can be obtained.

  Such a crystalline polypropylene resin (A) includes, for example, a Ziegler catalyst system comprising a solid catalyst component, an organoaluminum compound and an electron donor containing magnesium, titanium, halogen and an electron donor as essential components, or a metallocene compound. It can be produced by polymerizing propylene in a metallocene catalyst system or copolymerizing propylene and other α-olefins as a component of the catalyst.

Ethylene / α-olefin copolymer (B)
There is no restriction | limiting in particular in the alpha-olefin used for the ethylene / alpha-olefin copolymer (B) used in this invention, The alpha-olefin which can be copolymerized with ethylene can be used suitably. Usually, alpha olefins having 3 to 20 elemental numbers can be used singly or in combination of two or more. Of these, α-olefins having 4 or more carbon atoms are preferable, and those having 4 to 8 carbon atoms are particularly preferable. Examples of such α-olefins include 1-butene, 1-pentene, 1-hexene, 3-methyl-1-butene, 3,3-dimethyl-1-butene, 4-methyl-1-pentene, and 1-octene. 1 type, or 2 or more types of these are used. Of these, 1-butene, 1-pentene, 1-hexene and 4-methyl-1-pentene are preferred because of their availability. The ethylene / α-olefin copolymer (B) used in the present invention may be used in combination of two or more. Moreover, in the range which does not impair the objective of this invention, copolymerization components other than ethylene and an alpha olefin may be included.

  Moreover, it is preferable that the alpha-olefin content of the ethylene / alpha-olefin copolymer (B) used in this invention is 20 mol% or more and 70 mol% or less. When the α-olefin content is 20 mol% or more, the compatibility with the crystalline polypropylene resin (A) used together with the ethylene / α-olefin copolymer (B) is good, and the flexibility, transparency, and impact resistance are good. In the effect of improving the property, a polypropylene resin composition having a high balance can be obtained. When the content is 70 mol% or less, stickiness of the obtained resin composition can be suppressed, and the practical value is high. More specifically, when an α-olefin having 4 or more carbon atoms is used, 30 to 70 mol% of structural units derived from ethylene and a total of 70 structural units derived from α-olefins having 4 or more carbon atoms. It is preferable to have ~ 30 mol%. When the content of the α-olefin having 4 or more carbon atoms is within the above range, it is preferable from the viewpoint of balance of transparency, heat resistance, and whitening resistance.

  The degree of crystallinity of the ethylene / α-olefin copolymer (B) used in the present invention may be less than 30%, and there is no particular limitation, but if the degree of crystallinity is 10% or less, it is transparent. It is particularly preferable from the viewpoint of safety.

  The density of the ethylene / α-olefin copolymer (B) used in the present invention is in the range of 0.85 to 0.87. When the density is within this range, there is a preferable effect that a sealing agent having excellent flexibility can be obtained. The density can be measured by using a density gradient tube. The density is preferably 0.85 to 0.86, more preferably 0.851 to 0.858, and particularly preferably 0.855 to 0.859.

  The molecular weight of the ethylene / α-olefin copolymer (B) used in the present invention is not particularly limited, but the number average molecular weight measured by gel permeation chromatography (GPC) is 5000 to 5000 in terms of polyethylene. It is preferably 1000000, more preferably 10000 to 600000. When the number average molecular weight is in the range of 5,000 to 1,000,000, the effect of modifying the properties of the composition of the present invention is increased, and the problem of surface stickiness can be effectively suppressed.

  The molecular weight distribution (Mw / Mn) of the ethylene / α-olefin copolymer (B) used in the present invention is not particularly limited, but is preferably 3 or less. In general, it is known that when the molecular weight distribution is reduced, the composition distribution is also narrowed. When the composition distribution is narrow, the compatibility between the ethylene / α-olefin copolymer (B) and the crystalline polypropylene resin (A) is improved. Can be expected to do. Use the ratio of the average α-olefin content (mol%) in the low molecular weight fraction 10% to the average α-olefin content (mol%) in the high molecular weight fraction 10% fractionated by GPC as an index of composition distribution. However, when the ratio between the two is 1.2 or less, a product excellent in transparency and mechanical strength characteristics can be easily obtained, which is particularly preferable.

  The method for producing the ethylene / α-olefin copolymer described above is not particularly limited, and can be produced using various catalysts such as a titanium catalyst, a vanadium catalyst, or a metallocene catalyst. Among them, it is preferable to use a metallocene-based catalyst that can easily obtain an ethylene / α-olefin copolymer satisfying the above-described molecular weight, molecular weight distribution, and composition distribution.

Silane coupling agent (C)
The solar cell encapsulant of the present invention preferably further contains a silane coupling material (C). As a compounding quantity of a silane coupling material, a silane coupling agent is 0.1-0.1 with respect to a total of 100 weight part of the said crystalline polypropylene resin (A) and an ethylene / alpha-olefin copolymer (B). It is desirable to blend so as to be 5 parts by weight.

  The coupling agent is usually blended mainly for the purpose of improving the adhesion to glass, plastic and the like. In the present invention, the coupling agent can be used without particular limitation as long as it can improve the adhesion between the solar cell encapsulant of the present invention and other layers such as glass and polyester resin. , Titanate and chromium coupling agents are preferably used. In particular, a silane coupling agent (silane coupling agent) is preferably used.

  As the silane coupling agent (C), known ones can be used, and there are no particular restrictions, but specific examples include vinyltriethoxysilane, vinyltrimethoxysilane, vinyltris (β-methoxy-ethoxysilane), and γ-glycid. Xylpropyl-tripril trimethoxysilane, γ-aminopropyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane and the like can be used.

  The amount of the silane coupling agent (C) is such that the silane coupling agent (C) is based on 100 parts by weight of the total of the crystalline polypropylene resin (A) and the ethylene / α-olefin copolymer (B). Usually 0.1 to 5 parts by weight, preferably 0.1 to 3 parts by weight. It is preferable that the amount of the coupling agent is in the above range since the adhesiveness is sufficiently improved and the transparency and flexibility of the film are not adversely affected.

A radical initiator or a coupling agent typified by a silane coupling agent can be obtained by using a radical initiator to form the crystalline polypropylene resin (A) and / or the ethylene / α-olefin copolymer (B). It is possible to develop a stronger adhesive force with the glass by graft reaction. The radical initiator preferably used in the present invention is not particularly limited as long as it can graft the ethylene copolymer with a coupling agent. Of these, organic peroxides are particularly preferably used as radical initiators. In this case, the amount of the organic peroxide is preferably about 0 to 5 parts by weight with respect to 100 parts by weight as a total of the crystalline polypropylene resin (A) and the ethylene / α-olefin copolymer (B).

  Known organic peroxides can be used and are not particularly limited. Preferred examples include dilauroyl peroxide, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate. , Dibenzoyl peroxide, t-amylperoxy-2-ethylhexanoate, t-butylperoxy-2-ethylhexanoate, t-butylperoxyisobutyrate, t-butylperoxymaleic acid, 1 , 1-Di (t-amylperoxy) -3,3,5-trimethylcyclohexane, 1,1-di (t-amylperoxy) cyclohexane, t-amylperoxyisononanoate, t-amylperoxynormal Octoate, 1,1-di (t-butylperoxy) -3,3,5-trimethylcyclohexane, 1,1-di (t-butylperoxy) cyclohexa , T-butylperoxyisopropyl carbonate, t-butylperoxy-2-ethylhexyl carbonate, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, t-amyl-peroxybenzoate, t-butyl Peroxyacetate, t-butylperoxyisononanoate, t-butylperoxybenzoate, 2,2-di (butylperoxy) butane, n-butyl-4,4-di (t-butylperoxy) petitate, Methyl ethyl ketone peroxide, ethyl 3,3-di (t-butyl peroxy) butyrate, dicumyl peroxide, t-butyl cumyl peroxide, di-t-butyl peroxide, 1,1,3,3-tetralamethylbutyl Examples include hydroperoxide and acetylacetone peroxide.

Weathering Stabilizer The solar cell encapsulant of the present invention can further contain various weathering stabilizers. The compounding amount of the weather stabilizer is preferably 0 to 5 parts by weight with respect to 100 parts by weight as a total of the crystalline polypropylene resin (A) and the ethylene / α-olefin copolymer (B). When the blending amount of the weather resistance stabilizer is within the above range, the effect of improving the weather resistance stability can be sufficiently secured, and the transparency of the solar cell sealing material and the deterioration of the adhesiveness with the glass can be prevented. Therefore, it is preferable.

  As the weather resistance stabilizer, one or more compounds selected from ultraviolet absorbers, light stabilizers, antioxidants and the like can be used.

  Specific examples of the UV absorber include 2-hydroxy-4 methoxybenzophenone, 2-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-4-carboxybenzophenone, and 2-hydroxy-4-N. Benzophenone series such as octoxybenzophenone, 2- (2-hydroxy-3,5-di-t-butylphenyl) benzotriazole, benzotrialisol series such as 2- (2-hydroxy-5-methylphenyl) benzotriazole , Salicylic acid ester type compounds such as phenyl salicylate and p-octylphenyl salicylate are used.

  As the light stabilizer, a hindered amine type is preferably used. Further, as the antioxidant, a hindered phenol type or a phosphite type is used.

Other Components The solar cell encapsulant of the present invention can appropriately contain various components other than the components described in detail as long as the object of the present invention is not impaired. For example, various polyolefins other than the crystalline polypropylene resin (A) or the ethylene / α-olefin copolymer (B), such as an ethylene / α-olefin copolymer (B ′) having a density greater than 0.87, Examples thereof include styrene-based and ethylene-based block copolymers. These are 0.0001 parts by weight to 50 parts by weight, preferably 0.001 parts by weight, based on 100 parts by weight of the total amount of the crystalline polypropylene resin (A) and the ethylene / α-olefin copolymer (B). -40 parts by weight may be contained. Also, one or more kinds selected from various resins other than polyolefin and / or various rubbers, plasticizers, fillers, pigments, dyes, antistatic agents, antibacterial agents, antifungal agents, flame retardants, dispersants, etc. However, it is not limited to these.

Solar cell encapsulant The solar cell encapsulant of the present invention comprises 70 to 5 parts by weight of the crystalline polypropylene resin (A) and 30 to 95 parts by weight of the ethylene / α-olefin copolymer (B) ( The total of (A) and (B) includes 100 parts by weight. When the blending amount of (A) and (B) is in the above range, the heat resistance, transparency, flexibility and the like of the solar cell sealing sheet obtained together with good sheet moldability are improved, preferable. Since the crystalline polypropylene resin (A) is 70 parts by weight or less, the flexibility of the composition is good, and since it is 5 parts by weight or more, a decrease in strength can be prevented, which is preferable. The blend ratio can be arbitrarily changed within this range depending on the intended use form and required physical properties.

  As a method for producing the solar cell encapsulant of the present invention, a commonly used method can be used, but it is preferably produced by melt blending with a kneader, roll, Banbury mixer, extruder or the like.

  The solar cell encapsulant of the present invention preferably has two or more glass transition point peaks measured by temperature change of its loss tangent (tan δ). A glass transition point peak of 2 or more is preferable in that it has excellent low-temperature characteristics, particularly low-temperature impact strength. The temperature change of the loss tangent is 10 rad from −100 ° C. to 100 ° C. at a rate of temperature rise of 2 ° C./min. / S can be measured.

  Furthermore, the solar cell encapsulant of the present invention desirably has a maximum tangent loss of 0.1 or more. It is preferable that the maximum value of the tangent loss is 0.1 or more because the solar cell element is not damaged because of excellent flexibility. The tangent loss is more preferably 0.1 to 3, and still more preferably 0.2 to 2.

Solar cell encapsulating sheet A solar cell encapsulating sheet obtained using the solar cell encapsulating material of the present invention is one of the preferred embodiments of the present invention. This solar cell sealing sheet has at least one layer made of the solar cell sealing material of the present invention. Here, “consisting of” means that when the entire layer is made of the solar cell encapsulant, a part of the layer is made of the solar cell encapsulant, It is intended to include both.

  The thickness of the layer made of the solar cell sealing material of the present invention is usually 0.01 mm to 1 mm, preferably 0.05 to 0.8 mm. It is preferable for the thickness to be within this range because the glass and solar cells in the laminating step can be prevented from being damaged, and a sufficient amount of photovoltaic power can be obtained by securing sufficient light transmittance.

  Although there is no restriction | limiting in particular in the shaping | molding method of the layer which consists of a solar cell sealing material of this invention, Well-known various shaping | molding methods (Cast shaping | molding, extrusion sheet shaping | molding, inflation shaping | molding, injection molding, compression molding, calendar shaping | molding, etc.) It is possible to adopt. Moreover, it is possible to emboss the surface, and blocking the sealing sheets with each other by decorating the surface of this layer by embossing, or blocking between the sealing sheet and other sheets, Further, the embossing is preferable because it serves as a cushion for the solar cell element or the like at the time of lamination and prevents these damages.

  The layer made of the solar cell encapsulant of the present invention has an internal haze in the range of 1% to 60%, preferably 1% to 40% when measured with a sample having a thickness of 0.5 mm or less.

  The layer made of the sealing agent of the present invention has a light transmittance (transformer) at a thickness of 0.5 mm of 75% or more, preferably 80% or more. With such a light transmittance, the power generation efficiency is hardly lowered and can be suitably used in the present invention. In the measurement of the light transmittance, in order to remove the influence of the unevenness of the film surface, it is obtained by heating and pressing at 160 ° C. or higher while cooling with a smooth release film such as PET. About the obtained sample of the desired thickness, it measures, after removing films, such as said PET.

  The solar cell encapsulating sheet which is a preferred embodiment of the present invention may have at least one layer made of the solar cell encapsulating material of the present invention. Therefore, the number of layers made of the solar cell encapsulant of the present invention may be one, or two or more. From the viewpoint of simplifying the structure and reducing the cost, and from the viewpoint of effectively utilizing light by minimizing interface reflection between layers, a single layer is preferable.

  The solar cell encapsulating sheet, which is a preferred embodiment of the present invention, may be composed of only the layer comprising the solar cell encapsulating material of the present invention, or other than the layer containing the solar cell encapsulating material of the present invention. Layer (hereinafter also referred to as “other layers”).

  As examples of other layers, if classified according to the purpose, a hard coat layer, an adhesive layer, an antireflection layer, a gas barrier layer, an antifouling layer and the like for protecting the front surface or the back surface can be provided. If classified by material, layer made of UV curable resin, layer made of thermosetting resin, layer made of polyolefin resin, layer made of carboxylic acid modified polyolefin resin, layer made of fluorine-containing resin, cyclic olefin (co) A layer made of a polymer, a layer made of an inorganic compound, or the like can be provided.

  The positional relationship between the layer made of the solar cell encapsulating material of the present invention and the other layers is not particularly limited, and a preferable layer configuration is appropriately selected depending on the purpose of the invention. That is, the other layer may be provided between two or more layers made of the solar cell sealing material of the present invention, or may be provided in the outermost layer of the solar cell sealing sheet, or otherwise. It may be provided at the location. Other layers may be provided only on one side of the layer made of the solar cell encapsulant of the present invention, and other layers may be provided on both sides. There is no restriction | limiting in particular in the number of layers of another layer, Arbitrary number of other layers can be provided and it is not necessary to provide another layer.

  From the viewpoint of reducing the cost by simplifying the structure, and from the viewpoint of effectively utilizing light by minimizing interface reflection, the other layers are not provided, only the layer made of the solar cell sealing material of the present invention, What is necessary is just to produce the sealing sheet for solar cells, and if there exists other layers which are necessary or useful in relation to the objective, what is necessary is just to provide such other layers suitably.

  There are no particular restrictions on the method of laminating the layer composed of the solar cell encapsulant of the present invention and the other layer in the case of providing other layers, but it is a cast molding machine, extrusion sheet molding machine, inflation molding machine, injection molding machine. A method of obtaining a laminate by co-extrusion using a known melt extruder such as the above, or a method of obtaining a laminate by melting or heating and laminating the other layer on one previously formed layer. Also suitable adhesives (for example, maleic anhydride modified polyolefin resins (for example, Admer made by Mitsui Chemicals, Modic made by Mitsubishi Chemical), low (non) crystalline soft polymers such as unsaturated polyolefins, ethylene / Acrylic ester / maleic anhydride terpolymers (for example, bondine manufactured by Sumika DF Chemical Co., Ltd.), acrylic adhesives, ethylene / vinyl acetate copolymers or adhesive resin compositions containing these For example, a dry laminating method or a heat laminating method. As the adhesive, one having a heat resistance of about 120 ° C. to 150 ° C. is preferably used, and a polyester-based or polyurethane-based adhesive is exemplified as a suitable one. Moreover, in order to improve the adhesiveness of both layers, for example, a silane coupling treatment, a titanium coupling treatment, a corona treatment, a plasma treatment, or the like may be used.

  The solar cell encapsulating sheet of the present invention desirably has an internal haze in the range of 1% to 60%, preferably 5% to 50% when measured with a sample having a thickness of 0.5 mm or less.

Solar cell module The solar cell encapsulant of the present invention and the solar cell encapsulating sheet which is a preferred embodiment of the present invention have the excellent characteristics as described above. Therefore, the solar cell module obtained using such a solar cell encapsulant and / or solar cell encapsulating sheet can utilize the effects of the present invention, and is one of the preferred embodiments of the present invention. It is.

  Solar cell modules usually have a structure in which solar cell elements formed of polycrystalline silicon or the like are sandwiched and stacked between solar cell sealing sheets, and both front and back surfaces are covered with protective sheets. That is, a typical solar cell module is a solar cell module protective sheet (surface protective sheet) / solar cell sealing sheet / solar cell element / solar cell sealing sheet / solar cell module protective sheet (back surface protective sheet). It is the composition. However, the solar cell module which is one of the preferred embodiments of the present invention is not limited to the above-described configuration, and a part of each of the above layers is appropriately omitted as long as the object of the present invention is not impaired. Layers other than the above can be provided as appropriate. Typically, an adhesive layer, a shock absorbing layer, a coating layer, an antireflection layer, a back surface rereflection layer, a light diffusion layer, and the like can be provided, but not limited thereto. There is no particular limitation on the positions where these layers are provided, and the layers can be provided at appropriate positions in consideration of the purpose of providing such layers and the characteristics of such layers.

Although there is no restriction | limiting in particular in the surface protection sheet for solar cell modules preferably used in the solar cell module which is preferable embodiment of this invention, since it is located in the outermost layer of a solar cell module, it is a weather resistance In addition to water repellency, stain resistance, and mechanical strength, it is preferable to have performance for ensuring long-term reliability in outdoor exposure of the solar cell module. Moreover, in order to utilize sunlight effectively, it is preferable that it is a highly transparent sheet | seat with a small optical loss.

  As a material of the surface protection sheet for solar cell modules suitably used for the solar cell module, a resin film made of polyester resin, fluororesin, acrylic resin, cyclic olefin (co) polymer, ethylene-vinyl acetate copolymer, etc. In addition, a glass substrate etc. are mentioned.

  Particularly suitable as the resin film is a polyester resin excellent in transparency, strength, cost and the like, particularly a polyethylene terephthalate resin.

  A fluororesin having particularly good weather resistance is also preferably used. Specifically, tetrafluoroethylene-ethylene copolymer (ETFE), polyvinyl fluoride resin (PVF), polyvinylidene fluoride resin (PVDF), polytetrafluoroethylene resin (TFE), tetrafluoroethylene-6 There are fluorinated propylene copolymer (FEP) and poly (trifluorotrifluoroethylene resin) (CTFE). Polyvinylidene fluoride resin is excellent in terms of weather resistance, but tetrafluoroethylene-ethylene copolymer is excellent in terms of both weather resistance and mechanical strength. Moreover, it is desirable to perform a corona treatment and a plasma treatment on the surface protection sheet in order to improve the adhesiveness with a material constituting another layer such as a sealing material layer. It is also possible to use a sheet that has been subjected to stretching treatment for improving mechanical strength, for example, a biaxially stretched polypropylene sheet.

  When glass is used as the surface protection sheet for a solar cell module, the total light transmittance of light having a wavelength of 350 to 1400 nm is preferably 80% or more, and more preferably 90% or more. As such a glass substrate, it is common to use white plate glass with little absorption in the infrared part, but even blue plate glass has little influence on the output characteristics of the solar cell module if the thickness is 3 mm or less. Further, tempered glass can be obtained by heat treatment to increase the mechanical strength of the glass substrate, but float plate glass without heat treatment may be used. Further, an antireflection coating may be provided on the light receiving surface side of the glass substrate in order to suppress reflection.

Back surface protection sheet for solar cell module The back surface protection sheet for solar cell module used in the solar cell module which is a preferred embodiment of the present invention is not particularly limited, but is located on the outermost layer of the solar cell module, and thus the above-mentioned surface Like the protective sheet, various properties such as weather resistance and mechanical strength are required. Therefore, you may comprise the back surface protection sheet for solar cell modules with the material similar to a surface protection sheet. That is, the above-mentioned various materials that can be used in the surface protective sheet can also be used in the back surface protective sheet. In particular, a polyester resin and glass can be preferably used.

  Moreover, since the back surface protection sheet does not assume the passage of sunlight, the transparency required for the surface protection sheet is not necessarily required. Therefore, a reinforcing plate may be attached to increase the mechanical strength of the solar cell module or to prevent distortion and warpage due to temperature change. For example, a steel plate, a plastic plate, an FRP (glass fiber reinforced plastic) plate or the like can be preferably used.

Solar cell element The solar cell element in the solar cell module which is a preferred embodiment of the present invention is not particularly limited as long as it can generate power using the photovoltaic effect of a semiconductor. For example, silicon (single crystal, Crystalline, non-crystalline (amorphous) solar cells, compound semiconductor (Group 3-5, 2-6, etc.) solar cells, wet solar cells, organic semiconductor solar cells, and the like can be used. Among these, a polycrystalline silicon solar cell is preferable from the viewpoint of balance between power generation performance and cost.

  Both silicon and compound semiconductors have excellent characteristics as solar cell elements, but are known to be easily damaged by external stress, impact, and the like. Since the solar cell sealing material of the present invention is excellent in flexibility, it has a great effect of absorbing stress, impact, etc. on the solar cell element and preventing damage to the solar cell element. Therefore, in the solar cell module which is a preferred embodiment of the present invention, it is desirable that the layer made of the solar cell sealing material of the present invention is directly joined to the solar cell element.

  Further, when the solar cell encapsulant has thermoplasticity, it is possible to take out the solar cell element relatively easily even after the solar cell module is once manufactured, and it is excellent in recyclability. Yes. Since the essential component of the solar cell encapsulant of the present invention has thermoplasticity, it is easy to impart thermoplasticity to the entire solar cell encapsulant, which is preferable from the viewpoint of recyclability.

Power Generation Facility The solar cell module which is a preferred embodiment of the present invention is excellent in productivity, power generation efficiency, life and the like. For this reason, the power generation equipment using such a solar cell module is excellent in cost, power generation efficiency, life, etc., and has a high practical value.

The power generation equipment described above is suitable for long-term use regardless of whether it is outdoors or indoors, such as being installed on the roof of a house, used as a mobile power source for outdoor use such as camping, or used as an auxiliary power source for automobile batteries.
[Example]
Hereinafter, the present invention will be described more specifically with reference to examples. However, the scope of the present invention is not limited by the examples in any way.
(Measuring method)
In the following examples and comparative examples, various characteristics were measured by the following methods.
The strand after the MFR measurement at a density of 190 ° C. and a load of 2.16 kg was gradually cooled to room temperature over 1 hour, and then measured by a density gradient tube method.
-Composition The 13C-NMR measurement of a fixed method was performed, and the composition of the polymer was computed from the acquired spectrum.
Loss tangent (tan δ)
Using RDS-II manufactured by Rheometric Co., the measurement was performed at 10 rad / s from −100 to 100 ° C. at a temperature rising rate of 2 ° C./min in a torsion mode (twist) between a width of 10 mm and a length of 38 mm.
・ Transparency (internal haze)
A test piece having a thickness of 1 mm was immersed in benzyl alcohol filled in a predetermined cell, and measured with a digital turbidimeter “NDH-20D” manufactured by Nippon Denshoku Industries Co., Ltd.
-Flexibility Based on JIS K6301, a JIS No. 3 dumbbell was used, and measurement was performed at 23 ° C. with a span interval of 30 mm and a pulling speed of 30 mm / min.
-Heat resistance According to JIS K7196, using a 1 mm thick test piece, a pressure of ² Kg / cm ² was applied to a 1.8 mmφ flat indenter at a heating rate of 5 ° C / min. (° C.) was determined.
-Process stability The stability of the thickness at the time of sheet forming was visually observed for 3 hours and evaluated.

○: Stable without thickness variation ×: Defect due to thickness variation

・ Glass adhesion Hot plate that was prepared in a vacuum laminator by sandwiching the above sheet sample of 0.5 mm thickness between a transparent glass plate, which is an upper transparent protective material for solar cells, and a PET film, and temperature-controlled at 160 ° C. The glass plate / sheet sample / PET film laminate was prepared by placing on top and heating for 15 minutes. About this laminated body, between glass and a sheet | seat sample was peeled by hand, the peeling condition was observed, and the following three steps evaluated.

○: Adhesion good △: Adhesion slightly insufficient ×: Adhesion failure

(Materials used)
In the following examples and comparative examples, the types, manufacturing methods, physical properties, and the like of the resins used for preparing the samples are as follows.
(A-1) Crystalline Polypropylene Resin Isotactic polypropylene F327D (MFR = 7 g / 10 min, Tm = 139 ° C., crystallinity 38%) manufactured by Mitsui Chemicals, Inc. was used.
(B-1) Ethylene / α-Olefin Copolymer 845 ml of hexane was inserted at 23 ° C. into a SUS autoclave equipped with a stirrer having a capacity of 2 liters that had been sufficiently substituted with nitrogen. In this autoclave, 155 ml of 1-butene was inserted while rotating a stirrer and cooling with ice water. Next, the autoclave was heated to an internal temperature of 60 ° C., and further pressurized with ethylene so that the total pressure was 8 kg. When the internal pressure of the autoclave reached 8 kg, a 1.0 mM / ml decane solution of triisobutylaluminum (TIBA) was injected with 1.0 ml of nitrogen. Subsequently, methylaluminoxane prepared in advance was 0.3 mM in terms of Al, and rac-dimethylsilylene-bis [1- (2-methyl-4-phenyl-indenyl)] zirconium dichloride was added in an amount of 0.001 mM. A 0.3 ml toluene solution containing the solution was pressed into an autoclave with nitrogen to initiate polymerization.

  Thereafter, the temperature of the autoclave was adjusted to 60 ° C. for 30 minutes, and ethylene was directly supplied so that the pressure became 8 kg. 30 minutes after the start of polymerization, 5 ml of methanol was inserted into the autoclave by a pump to stop the polymerization, and the autoclave was depressurized to atmospheric pressure. 2 l of acetone was poured into the reaction solution with stirring.

The obtained rubber-like polymer containing the solvent was dried at 130 ° C. for 13 hours at 600 torr. The ethylene content was 59 mol%, the butene content was 41 mol%,
As a result, 47 g of an ethylene / 1-butene copolymer having a density = 0.589 g / cm ³ , Mw / Mn = 2.4, MFR = 1 g / 10 min, and a crystallinity of 0% was obtained. This was used in the following examples.
(B′-2) Ethylene / α-olefin Copolymer Ethylene / Butene Copolymer (Density = 0.85 g / cm ³ , C2 Content 88 mol%, C4 Content 12 mol%, MFR = 4 g / Mitsui Chemical Co., Ltd.) 10 min, crystallinity 13%) was used.
(C-1) Silane coupling agent γ-methacryloxypropyltrimethoxysilane (KBM503, manufactured by Shin-Etsu Chemical Co., Ltd.) was used.
[Example 1]
From a blend of (A-1) 30 parts by weight of a crystalline polypropylene resin and 70 parts by weight of (B-1) an ethylene / α-olefin copolymer, using a sheet molding machine at 200 ° C., a thickness of 0. A 5 mm sheet was prepared.

Table 1 shows the physical properties of the obtained sheet.
[Example 2]
A blend comprising (A-1) 30 parts by weight of a crystalline polypropylene resin, (B-1) 50 parts by weight of an ethylene / α-olefin copolymer, and (B′-2) 20 parts by weight of an ethylene / α-olefin copolymer. From the product, a sheet having a thickness of 0.5 mm was produced at 200 ° C. using a sheet molding machine.

Table 1 shows the physical properties of the obtained sheet.
[Example 3]
(C-1) Silane coupling agent 0 with respect to 100 parts by weight of (A-1) crystalline polypropylene resin 30 parts by weight and (B-1) 70 parts by weight of ethylene / α-olefin copolymer. A sheet having a thickness of 0.5 mm was prepared from the blend containing 5 parts by weight at 200 ° C. using a sheet molding machine.

Table 1 shows the physical properties of the obtained sheet.
[Comparative Example 1]
(A-1) From a blend consisting of 30 parts by weight of a crystalline polypropylene resin (B′-2) and 70 parts by weight of an ethylene / α-olefin copolymer, using a sheet molding machine, the thickness is 200 ° C. A 0.5 mm sheet was prepared.

  Table 1 shows the physical properties of the obtained sheet.

Claims (8)

Crystalline polypropylene-based resin (A) 70 to 5 parts by weight and ethylene / α-olefin copolymer (B) 30 to 95 parts by weight ((A) and (B )) Is a solar cell encapsulant comprising 100 parts by weight. The solar cell sealing material according to claim 1, wherein the ethylene / α-olefin copolymer (B) has a structural unit derived from an α-olefin having 4 or more carbon atoms. The ethylene / α-olefin copolymer (B) has 30 to 70 mol% of structural units derived from ethylene, and a total of 70 to 30 mol% of structural units derived from an α-olefin having 4 or more carbon atoms, The solar cell sealing material according to claim 2. The solar cell sealing material of Claim 1 which has two or more glass transition point peaks measured by the temperature change of loss tangent (tan-delta). Furthermore, the solar cell sealing material of any one of Claim 1 to 4 which comprises a silane coupling agent (C). The solar cell sealing sheet obtained using the solar cell sealing material of any one of Claims 1-5. The solar cell module obtained using the solar cell sealing material of any one of Claims 1-5, and / or the solar cell sealing sheet of Claim 6. A power generation facility obtained using the solar cell module according to claim 7.