JP6045126B2 - Multilayer protective sheet and solar cell module using the same - Google Patents

Description

  The present invention relates to a protective sheet for a solar cell module, and more particularly to a multilayer protective sheet that can be directly laminated on a sealing material sheet.

  In recent years, solar cells as a clean energy source have attracted attention due to the growing awareness of environmental issues. In general, a solar cell module constituting a solar cell includes a transparent front substrate such as glass, a surface side sealing material sheet, a solar cell element, a back side sealing material sheet, and a back surface protection sheet from the light receiving surface side. The structure is laminated in order, and has a function of generating electric power when sunlight enters the solar cell element.

  The solar cell module is used outdoors for a long period of time. Therefore, the above-mentioned members constituting the solar cell module are required to have durability capable of withstanding harsh environments outdoors for a long period of time. Especially, the back surface protection sheet has a high space between the back surface side sealing material sheet and Adhesion is required.

  As such a back surface protective sheet, the following Patent Document 1 discloses a single-layer or multilayer solar cell sheet having a polyphenylene ether-based resin layer made of a resin composition containing polyphenylene ether as a main component.

JP 2010-278428 A

  According to Patent Document 1, it is possible to improve the adhesion between the polyphenylene ether-based resin layer serving as the back surface protection sheet and the sealing material sheet, and in particular, the high sealing material sheet containing the crosslinking agent. Adhesion can be achieved.

  However, since polyphenylene ether is an aromatic polyether, it has a structure that easily absorbs ultraviolet rays at the portion of the aromatic skeleton, whereby the deterioration of the resin is remarkably inferior in weather resistance. For this reason, it is actually impossible to use the polyphenylene ether-based resin layer as a single layer and expose it to the outermost layer.

  The present invention has been made in view of the above situation, and has a very high adhesiveness with a sealing material sheet, and in particular, a multilayer protective sheet excellent in weather resistance such as prevention of ultraviolet deterioration and the like An object of the present invention is to provide a solar cell module using the above.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have arranged the protective sheet as a multilayer structure and arranged the second resin sheet containing the modified polyphenylene ether resin on the side to be the laminated surface with the sealing material sheet At the same time, the inventors have found that a protective sheet excellent in weather resistance can be obtained by providing a layer containing an ultraviolet shielding material on the opposite side of the laminated surface to prevent ultraviolet deterioration. The present invention has been completed. More specifically, the present invention provides the following.

(1) A multilayer protective sheet disposed so as to be exposed on one of the front and back surfaces of the solar cell module,
A weather-resistant first resin sheet disposed on the exposed surface side;
A second resin sheet containing a modified polyphenylene ether, which is laminated directly or via another layer on the non-exposed surface side of the first resin sheet,
A multilayer protective sheet containing an ultraviolet shielding material in the first resin sheet and / or in the other layer.

  (2) The multilayer protective sheet according to (1), wherein the modified polyphenylene ether contains 5 to 20% by mass of a styrene resin.

(3) The multilayer protective sheet according to (1) or (2), a sealing material sheet containing a crosslinking agent, and a solar cell element are laminated,
The solar cell module in which the second resin sheet of the multilayer protective sheet and the sealing material sheet containing the crosslinking agent are directly laminated.

  (4) The solar cell module according to (3), wherein the sealing material sheet is an ethylene-vinyl acetate copolymer resin containing a crosslinking agent or a polyethylene resin containing a crosslinking agent.

  ADVANTAGE OF THE INVENTION According to this invention, while exhibiting very high adhesiveness between the sealing material sheets containing a crosslinking agent, the multilayer protective sheet which is excellent in a weather resistance, especially ultraviolet-ray resistance, and a solar cell module using the same are provided. Is done.

It is a schematic diagram which shows an example of the laminated structure of the multilayer protective sheet of this invention. It is a schematic diagram which shows an example of the laminated structure of the solar cell module of this invention.

<Back protection sheet>
First, the back surface protection sheet 6 which is an example of the multilayer protection sheet of this invention is demonstrated using FIG. The back protective sheet 6 includes a first resin sheet 61 and a third resin sheet 63 laminated from the exposed surface side through an adhesive layer 64, and further a third resin sheet 63 and a second resin sheet 62. Are laminated via an adhesive layer 65 to form a laminate of three layers of resin sheets. The intermediate third resin sheet 63 has a role of providing a function necessary as a protective sheet used in the solar cell module, but is not essential in the present invention.

<First resin sheet>
The 1st resin sheet 61 is located in the surface of the back surface side of a solar cell module, when the back surface protection sheet 6 is used for a solar cell module. Therefore, the 1st resin sheet 61 uses what was excellent in a weather resistance, heat resistance, light resistance, etc. In this specification, the term “resin sheet” is used as the name of the resin processed into a sheet shape, but this term is used as a concept including a resin film.

  Such resin sheets include PCTFE (polychlorotrifluoroethylene), PFA (tetrafluoroethylene perfluoroalkyl vinyl ester copolymer), PTFE (polytetrafluoroethylene), ETFE (tetrafluoroethylene / ethylene copolymer). Polymer), fluorine resins such as PVDF (polyvinylidene fluoride), cyclopropene, cyclobutene, cyclopentene, cyclohexene, cycloheptene, 1,3-cyclohexadiene, 1,4-cyclohexadiene, 1,5-cyclooctadiene, etc. Cyclic polyethylene, polypropylene, polystyrene, ethylene / propylene copolymer, ethylene / styrene copolymer, propylene / styrene copolymer, poly 1,4-cyclopentadiene, poly 1,5-hexadiene, etc. as monomers Reolefin resins, polycarbonate resins using alkylene carbonate and diol as raw materials, poly (meth) acrylic resins such as polymethyl methacrylate and polyacrylate, PET (polyethylene terephthalate), PBT (polybutylene terephthalate), PTT (poly) A resin sheet such as a polyester resin such as trimethylene terephthalate) is preferably exemplified. Among these, it is preferable from the viewpoint of weather resistance to use a fluorine-based resin typified by ETFE.

  In the present embodiment, as the various resin sheets, for example, one or more of the various resins described above are used, and an extrusion method, a cast molding method, a T-die method, a cutting method, an inflation method, and the like. Examples thereof include those formed by using a film forming method. In the present embodiment, the thickness of the resin sheet used as the first resin sheet 61 is not particularly limited, but is preferably 5 to 250 μm, more preferably 10 to 150 μm, and most preferably 20 to 80 μm. When the thickness of the 1st resin sheet 61 is 5 micrometers or more, sufficient weather resistance and light resistance can be provided to the back surface protection sheet 6, and the thickness of the 1st resin sheet 61 is 250 micrometers or less. The film transportability at the time of lamination can be imparted.

  Next, in this embodiment, the ultraviolet shielding material 66 is contained in the first resin sheet 61. The ultraviolet shielding material 66 is provided to protect the second resin sheet 62 that is particularly vulnerable to ultraviolet rays from ultraviolet rays that are incident from the back side of the solar cell module. That is, the ultraviolet shielding material 66 is provided in the back surface protection sheet 6 to protect each layer present on the inner side of the solar cell module from the ultraviolet shielding material 66 from ultraviolet rays.

  The ultraviolet shielding material 66 is a material for reflecting or absorbing ultraviolet rays. Specifically, examples of the organic ultraviolet absorbing material include a reflecting material, an inorganic ultraviolet absorbing material or a reflecting material, and these are particularly limited. It can be used without being. However, from the viewpoint that the back surface protection sheet 6 may be exposed to high humidity and high temperature, an inorganic ultraviolet shielding material 66 that is stable against high humidity and high temperature conditions is preferably used. Examples of such an ultraviolet shielding material 66 include fine particles of titanium oxide and zinc oxide. As a result, in this case, the first resin sheet 61 is colored white.

  When titanium oxide fine particles are used as an ultraviolet shielding material, the particle diameter is preferably 20 to 1200 nm, and more preferably 80 to 600 nm. The content of the ultraviolet shielding material is preferably 3 to 80% by mass, and more preferably 10 to 40% by mass. When the ultraviolet shielding material 66 is 3 mass% or more, a sufficient ultraviolet shielding effect can be imparted to the ultraviolet shielding material 66. Moreover, physical characteristics, such as the intensity | strength of the 1st resin sheet 61, can be maintained because it is 80 mass% or less.

  In the first resin sheet 61, for example, other properties such as sheet processability, heat resistance, weather resistance, mechanical properties, dimensional stability, antioxidant properties, slip properties, mold release properties, flame retardancy, and antifungal properties are provided. Various plastic compounding agents, additives and the like can be added as necessary for the purpose of improving and modifying the electrical characteristics, strength, and the like.

<Second resin sheet>
The second resin sheet 62 is a resin sheet containing modified polyphenylene ether that is laminated on the non-exposed surface side of the first resin sheet 61 via a third resin sheet 63 that is an example of another layer in this embodiment. It is. In the present invention, other layers are not necessarily required, and the second resin sheet 62 may be laminated directly on the first resin sheet 61.

  The second resin sheet 62 is a resin sheet containing a modified polyphenylene ether as a main component, and the thickness thereof is not particularly limited, but is preferably 15 μm or more because necessary mechanical strength is obtained, and if it is 250 μm or less, necessary processing is performed. It is preferable because aptitude is obtained.

  The modified polyphenylene ether may be a polymer alloy in which a main component is polyphenylene ether (PPE) having an aromatic polyether structure, and a thermoplastic resin such as a styrene resin is blended with it for the purpose of improving moldability. Although preferable, it may be modified by copolymerization. The thermoplastic resin mixed with the polyphenylene ether is not particularly limited, but use of a styrene resin is preferable.

  Modified polyphenylene ether is excellent in heat resistance and hydrolysis resistance due to its chemical structure. Further, the glass transition point (Tg) is as high as 150 to 190 ° C., and there is little thermal deformation during heating. Furthermore, as will be described later, since it has excellent adhesiveness with a sealing material sheet containing a crosslinking agent, it can be directly joined to the sealing material sheet without using an adhesive primer in the modularization of solar cells. High adhesive strength can be obtained. And in this invention, the ultraviolet-ray resistance which is a fault of modified polyphenylene ether can be provided by setting it as the laminated body combined with the ultraviolet shielding agent provided in the exposed surface side.

  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 styrene 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 amount of modification in the modified polyphenylene ether, that is, the styrene resin content is important, and is preferably 5 to 20% by mass, more preferably 5 to 10% by mass. Less than 5% by mass is not preferable because the sheet is brittle and inferior in moldability, and more than 20% by mass is not preferable because the adhesiveness with the sealing material sheet is lowered. The modified polyphenylene ether can usually impart formability as a sheet by increasing the modification rate, but on the other hand, the adhesion to the encapsulant sheet decreases in inverse proportion to this. That is, moldability and adhesiveness are in a trade-off relationship. Here, in this invention, long-term adhesiveness can further be improved by setting it as the modification rate lower than usual as mentioned above. Such a low modification rate is usually not performed, and in a field where a very long-term high durability is required, such as a solar cell module, the adhesiveness with the sealing material sheet is specifically maintained high. This is a request from the need and is unique to the field.

  The second resin sheet 62 may contain a resin other than the modified polyphenylene ether resin within a range that does not impair the effects of the present invention. Also, for example, workability, heat resistance, light resistance, weather resistance, mechanical properties, dimensional stability, antioxidant properties, slipperiness, mold release properties, flame retardancy, antifungal properties, electrical properties, etc. Various plastic compounding agents and additives, other resins, and the like can be added for the purpose of improvement and modification. 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.

<Third resin sheet>
The third resin sheet 63 is disposed between the first resin sheet 61 and the second resin sheet 62 and is used as an intermediate sheet for imparting insulation to the back surface protection sheet 6. For this reason, the third resin sheet 63 is not particularly limited as long as it is an electrically insulating resin sheet. However, in the back surface protection sheet 6 of the present embodiment, the above-described ultraviolet shielding material 66 is present in the first resin sheet 61, so that the third resin sheet 63 has a slightly low light resistance and therefore a low cost material. Can be used. That is, as the third resin sheet 63, a resin sheet having light resistance, that is, inferior in ultraviolet resistance, to the first resin sheet 61 located on the exposed surface side can be used.

  Examples of the third resin sheet 63 include polyethylene resin, polypropylene resin, cyclic polyolefin resin, polystyrene resin, acrylonitrile-styrene copolymer, acrylonitrile-butadiene-styrene copolymer, and polyvinyl chloride. Resin, polyvinyl chloride resin, poly (meth) acrylic resin, polycarbonate resin, polyester resin such as polyethylene terephthalate (PET), polyethylene naphthalate, various polyamide resins such as nylon, polyimide resin, polyamideimide Resin, polyaryl phthalate resin, silicone resin, polysulfone resin, polyphenylene sulfide resin, polyethersulfone resin, polyurethane resin, acetal resin, cellulose resin, etc. Mentioned resin sheet is. Among these resin sheets, the third resin sheet 63 is a resin sheet such as polyethylene terephthalate (PET) or silica-deposited polyethylene terephthalate (silica-deposited PET) polyolefin from the viewpoint of insulation performance, mechanical strength, cost, transparency, and the like. Preferably used. When it is necessary to impart gas barrier properties such as water vapor barrier properties to the back surface protective sheet 6, a transparent vapor deposition layer made of a metal oxide may be formed on the surface of the third resin sheet 63. In this case, the kind of metal oxide to be deposited, the thickness of the deposited layer, and the like may be appropriately set in consideration of the performance required for the back surface protection sheet 6.

  The resin is thinned and processed into a sheet-like third resin sheet 63 by a method similar to the method for producing the first resin sheet 61 already described. Further, the thickness of the third resin sheet 63 is preferably exemplified by the same range as that in the first resin sheet 61, but is not particularly limited.

<Adhesive layer>
In this embodiment, the 1st resin sheet 61 and the 3rd resin sheet 63 are laminated | stacked via the adhesive bond layer 64, and also the 3rd resin sheet 63 and the 2nd resin sheet 62 are adhesive layer. 65 are stacked. Conventionally known laminate adhesives for forming the adhesive layer 64 and the adhesive layer 65 can be used and are not particularly limited. A two-component curable dry agent composed of a main agent such as urethane or epoxy and a curing agent. A laminate adhesive or the like can be used as appropriate.
<Modified example of UV shielding material>
The ultraviolet shielding material may be contained not only in the first resin sheet 61 but also in “another layer” in the present invention. The other layer referred to here is a layer disposed on the exposed surface side from the second resin sheet 62, and may be in the third resin sheet 63 in the embodiment, and may be the adhesive layer 64 or the adhesive layer 65. It may be inside. Thus, the other layer in the present invention means not only a resin sheet but also an adhesive layer and other coating layers.

<Solar cell module>
Next, an example of a solar cell module using the back surface protection sheet 6 will be described with reference to FIG. As shown in FIG. 2, the solar cell module 1 includes a transparent front substrate 2, a front sealing material sheet 3, a solar cell element 4, a back sealing material sheet 5, and a back surface protection sheet from the incident light receiving surface side. 6 are laminated in order. Here, the back surface protection sheet 6 is laminated so that the second resin sheet 62 is on the non-exposed surface side, that is, the back surface sealing material sheet 5 side. A conventionally well-known thing can be used for structural members, such as the transparent front substrate 2 and the solar cell element 4, and it does not specifically limit. For modularization, the solar cell element 4 is sanded with the front sealing material sheet 3 and the back sealing material sheet 5, and then the transparent front substrate 2 and the back surface protection sheet 6 are sequentially laminated and integrated by, for example, vacuum heat laminating. Turn into. In this case, the laminating temperature is preferably in the range of 130 ° C to 190 ° C. The laminating time is preferably in the range of 5 to 60 minutes, particularly preferably in the range of 8 to 40 minutes.

  And in this embodiment, since the ultraviolet-ray shielding material 66 is contained in the 1st resin sheet 61 in this embodiment, the 2nd resin sheet 62 especially weak to an ultraviolet-ray can be protected from an ultraviolet-ray, and the 2nd resin sheet 62 is shown. Can prevent UV degradation.

  In addition, it cannot suppress that the ultraviolet-ray which injects from the light-receiving surface side of a solar cell module reaches the 2nd resin sheet 62 only with the ultraviolet-ray shielding material 66. FIG. However, even in this case, since an ultraviolet absorber is usually used in the sealing material sheet in the solar cell module, the ultraviolet rays incident from the light receiving surface side of the solar cell module reach the second resin sheet 62. In this respect, the second resin sheet 62 containing the modified polyphenylene ether can be protected from ultraviolet rays.

<Rear sealing material sheet>
In this integration process, when the second resin sheet 62 disposed on the outermost layer on the non-exposed surface side of the back surface protective sheet 6 and the back surface sealing material sheet 5 are laminated in a heated state, the back surface sealing material sheet Crosslinking of the back sealing material sheet 5 itself proceeds by the crosslinking agent contained in 5. In the present invention, the crosslinking reaction between the resin constituting the back sealing material sheet 5 and the modified polyphenylene ether also proceeds in parallel with this, and as a result, the back sealing material sheet 5 and the second resin sheet 62 Are firmly bonded. Thus, the encapsulant sheet in the present invention, particularly the back encapsulant sheet 5 is characterized by containing a cross-linking agent, so that even in the primerless configuration without an adhesive layer, which has been conventionally required, the back surface The protection sheet 6 and the back surface sealing material sheet 5 can be bonded.

  The resin composition constituting the back surface sealing material sheet 5 contains a cross-linking agent in the stage before the integration step with the back surface protective sheet 6 in order to achieve an effect of high adhesive strength with the back surface protective sheet 6. It is necessary to be. Preferred examples of the resin constituting the encapsulant sheet include an ethylene-vinyl acetate copolymer resin mainly containing an ethylene-vinyl acetate copolymer (EVA) and a polyethylene resin mainly containing low-density polyethylene.

[Polyethylene resin]
Preferred polyethylene resins include low density polyethylene (LDPE) having a density of 0.900 g / cm ³ or less, preferably linear low density polyethylene (LLDPE). The linear low density polyethylene is a copolymer of ethylene and an α-olefin, and the density thereof is 0.900 g / cm ³ or less, preferably 0.870 to 0.890 g / cm ³ . If it is this range, favorable transparency and heat resistance can be provided, maintaining sheet workability.

  In the present invention, it is preferable to use a metallocene linear low density polyethylene. Metallocene linear low density polyethylene is synthesized using a metallocene catalyst which is a single site catalyst. Such polyethylene has few side chain branches and a uniform distribution of comonomer. For this reason, molecular weight distribution is narrow and it is possible to make it the above ultra-low density. In addition, since the crystallinity distribution is narrow and the crystal sizes are uniform, not only a large crystal size does not exist, but also the crystallinity itself is low due to the low density. For this reason, it is excellent in transparency when processed into a sheet shape.

  As the α-olefin of the linear low density polyethylene, an α-olefin having no branch is preferably used. Among these, 1-hexene and 1-heptene which are α-olefins having 6 to 8 carbon atoms are preferable. Or 1-octene is particularly preferably used. When the α-olefin has 6 to 8 carbon atoms, the solar cell module sealing material can be provided with good flexibility and good strength. As a result, the adhesiveness between the sealing material and the base material is increased, and moisture intrusion between the sealing material and the base material can be suppressed.

  The melt mass flow rate (MFR) of the polyethylene resin needs to be 1.0 g / 10 min or more and 40 g / 10 min or less at 190 ° C., and preferably 2 g / 10 min or more and 40 g / 10 min or less. When the MFR is in the above range, the processability during film formation is excellent.

  Polyethylene resins include not only ordinary polyethylene obtained by polymerizing ethylene, but also resins obtained by polymerizing compounds having ethylenically unsaturated bonds such as α-olefins, ethylenically unsaturated bonds. And a modified resin obtained by grafting another chemical species to these resins. Among these, a silane copolymer obtained by copolymerizing at least an α-olefin and an ethylenically unsaturated silane compound as a comonomer can be preferably used. By using such a resin, adhesion between a sealing material and a member such as a transparent front substrate or a solar cell element can be obtained.

  The silane copolymer is described in, for example, Japanese Patent Application Laid-Open No. 2003-46105, and at least an α-olefin and an ethylenically unsaturated silane compound are used as a comonomer, and another unsaturated monomer is added as necessary. It is a copolymer obtained by copolymerization as a comonomer, and includes a modified product or a condensate of the copolymer. By using the copolymer as a component of the encapsulant composition of the solar cell module, it is excellent in strength, durability, etc., and weather resistance, heat resistance, water resistance, light resistance, wind pressure resistance, yield resistance In addition, it has excellent other characteristics, and has extremely excellent heat-sealability without being affected by manufacturing conditions such as thermocompression bonding for manufacturing solar cell modules. A solar cell module suitable for the above can be manufactured.

  Examples of the α-olefin include ethylene, propylene, 1-butene, isobutylene, 1-pentene, 2-methyl-1-butene, 3-methyl-1-butene, 1-hexene, 1-heptene, 1-octene, One or more selected from 1-nonene and 1-decene can be used.

  Examples of the ethylenically unsaturated silane compound include vinyl trimethoxy silane, vinyl triethoxy silane, vinyl tripropoxy silane, vinyl triisopropoxy silane, vinyl tributoxy silane, vinyl tripentyloxy silane, vinyl triphenoxy silane, vinyl tri One or more selected from benzyloxysilane, vinyltrimethylenedioxysilane, vinyltriethylenedioxysilane, vinylpropionyloxysilane, vinyltriacetoxysilane, and vinyltricarboxysilane can be used.

The content of the polyethylene resin having a density of 0.900 g / cm ³ or less contained in the composition is preferably 10% by mass to 99% by mass, more preferably 50% by mass to 99% by mass in the composition. More preferably, it is 90 to 99% by mass. In other words, other resins may be contained within this range. For example, other polyethylene resins exceeding 0.900 g / cm ³ can be exemplified. These may be used, for example, as an additive resin, and can be used for masterbatching other components described later.

[Crosslinking agent]
A well-known thing can be used for a crosslinking agent, It does not specifically limit, For example, a well-known radical crosslinking agent can be used. Examples of the radical crosslinking agent include hydroperoxides such as diisopropylbenzene hydroperoxide and 2,5-dimethyl-2,5-di (hydroperoxy) hexane; di-t-butyl peroxide, t-butyl cumi Dialkyl such as ruperoxide, dicumyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, 2,5-dimethyl-2,5-di (t-peroxy) hexyne-3 Peroxides; diacyl peroxides such as bis-3,5,5-trimethylhexanoyl peroxide, octanoyl peroxide, benzoyl peroxide, o-methylbenzoyl peroxide, 2,4-dichlorobenzoyl peroxide; t -Butyl peroxyacetate, t-butyl peroxy 2-ethylhexanoate, t-butyl peroxypivalate, t-butyl peroxyoctoate, t-butyl peroxyisopropyl carbonate, t-butyl peroxybenzoate, di-t-butyl peroxyphthalate, 2,5 Peroxyesters such as 2-dimethyl-2,5-di (benzoylperoxy) hexane, 2,5-dimethyl-2,5-di (benzoylperoxy) hexyne-3, t-butylperoxy-2-ethylhexyl carbonate Organic peroxides such as ketone peroxides such as methyl ethyl ketone peroxide and cyclohexanone peroxide, or azo compounds such as azobisisobutyronitrile and azobis (2,4-dimethylvaleronitrile), dibutyltin diacetate Dibutyltin dilaurate di Chill dioctoate, dioctyltin dilaurate, may be mentioned silanol condensation catalyst such as dicumyl peroxide, such as.

  For example, when the resin constituting the encapsulant sheet is EVA, the encapsulant sheet is uncrosslinked during sheet molding, and when the encapsulant sheet is crosslinked by heating during modularization, An organic peroxide having a one-hour half-life temperature of 100 ° C to 150 ° C is preferred.

  As content of the crosslinking agent in this case, it is preferable that 0.5 mass%-2.0 mass% is contained in a composition, More preferably, 0.5 mass%-1.5 mass% are contained. More preferably, it is the range of 0.5 mass part-1.0 mass part. If it is less than 0.5 parts by mass, the heat resistance at high temperature is inferior due to insufficient crosslinking, which is not preferable. If the amount exceeds 2.0 parts by mass, radicals may be generated and foaming may cause problems due to modularization. In addition, unreacted residual crosslinking agent may cause crosslinking during storage, and storage stability as a sealing material may be increased. It is not preferable because it may decrease.

  For example, when the resin constituting the encapsulant sheet is, for example, the above-described polyethylene-based resin, crosslinking including weak crosslinking described later can be performed at the time of sheet molding. In this case, among the above, t-butylperoxy 2-ethylhexyl carbonate, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane and the like can be preferably used. Since the active oxygen content is as high as 5% or more, and the 1-minute half-life temperature of the crosslinking agent is 160 to 190 ° C. and is consumed at the time of molding, an excessive amount of crosslinking agent remains after molding of the sealing material sheet. It is preferable because the progress of excessive post-crosslinking due to can be suppressed. A one-minute half-life temperature of less than 160 ° C. is not preferable because it is difficult to allow the crosslinking reaction to proceed after sufficiently dispersing the crosslinking agent during molding.

  The content of the crosslinking agent in this case is 0.02% by mass or more and less than 0.5% by mass in the composition, and the upper limit is preferably 0.2% by mass or less, more preferably 0.1% by mass or less. is there. If it is less than this range, the weak crosslinking of the polyethylene resin does not proceed and the heat resistance is insufficient. Moreover, when this range is exceeded, film forming property will fall, for example, gel will generate | occur | produce during shaping | molding, and transparency will also fall.

  In addition, when weak crosslinking is performed at the time of molding a sealing material sheet with a small amount of a crosslinking agent as described above, a molding method usually used in ordinary thermoplastic resins, that is, injection molding, extrusion molding, hollow molding, compression molding, Although it is carried out by various molding methods such as rotational molding, the molding temperature is preferably the melting point of the polyethylene resin + 50 ° C. or higher in order to promote a weak crosslinking reaction during molding. Specifically, a high temperature of 150 to 250 ° C. is preferable, and a range of 190 to 230 ° C. is more preferable. Since the addition of the crosslinking agent is small, the MFR is reduced, but the degree of the reduction is small. For this reason, weak crosslinking can be advanced during melt molding. Since the molding temperature is equal to or higher than the 1 minute half-life temperature of the crosslinking agent, the crosslinking agent hardly remains after molding, and the weak crosslinking is completed at this molding stage. However, surprisingly, even when there is almost no cross-linking agent after molding of the sealing material sheet, the adhesive strength of the back surface protection sheet to the second resin sheet is greatly improved. Thus, even if it is a very small amount of residual crosslinking agent, it is not disclosed or suggested in Patent Document 1 that the adhesive strength is greatly improved, which is a novel point of the present invention. From the above, “containing a crosslinking agent” in the present invention is meant to include such a small amount of residual crosslinking agent.

[Other ingredients]
The resin composition can further contain other components. Examples of the weather resistance masterbatch for imparting weather resistance, various fillers, light stabilizers, ultraviolet absorbers, heat stabilizers and the like are exemplified. These contents vary depending on the particle shape, density and the like, but are preferably in the range of 0.001 to 5% by mass in the resin composition. By including these additives, it is possible to impart a mechanical strength that is stable over a long period of time, an effect of preventing yellowing, cracking, and the like.

  A weatherproof masterbatch is obtained by dispersing a light stabilizer, an ultraviolet absorber, a heat stabilizer, the above-mentioned antioxidant, etc. in a resin such as polyethylene, and is good when added to a resin composition. Weather resistance can be imparted. The weatherproof masterbatch may be prepared and used as appropriate, or a commercially available product may be used. These light stabilizers, ultraviolet absorbers, heat stabilizers and antioxidants can be used alone or in combination of two or more. In addition to the above, other components used in the resin composition include adhesion improvers such as silane coupling agents, nucleating agents, dispersants, leveling agents, plasticizers, antifoaming agents, flame retardants, and the like. Can do.

EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to a following example.
<Example 1>
1 is coated with an adhesive 4.0 to 6.0 g / m ² (dry state) by a conventionally known dry laminating method to form an adhesive layer. And the back surface protection sheet of an Example and a comparative example was produced by laminating | stacking and aging at 40 degreeC for 5 days.

First resin sheet 61: White ETFE sheet having a thickness of 25 μm (made by Asahi Glass Co., Ltd., trade name “Aflex”, containing 20% by mass of titanium oxide having a particle size of 300 nm)
Third resin sheet 63: 125 μm thick polyethylene terephthalate (PET) sheet (trade name “S10” manufactured by Toray Industries, Inc.)
Second resin sheet 62 (Example 1): modified polyphenylene ether sheet having a thickness of 50 μm (poly (2,6-dimethylphenylene-1,4-ether), styrene content: 7% by mass)
Second resin sheet 62 (Example 2): Modified polyphenylene ether sheet having a thickness of 50 μm (poly (2,6-dimethylphenylene-1,4-ether), styrene content 40% by mass)
Second resin sheet (Comparative Example 1): Syndiotactic polystyrene (SPS) sheet having a thickness of 50 μm (trade name “Zarek” manufactured by Idemitsu Kosan Co., Ltd.)
Second resin sheet (Comparative Example 2): Polyphenylsulfone (PPS) sheet having a thickness of 50 μm (trade name “Torelina” manufactured by Toray Industries, Inc.)
Second resin sheet (Comparative Example 3): Polyethylene terephthalate (PET) sheet having a thickness of 50 μm (trade name “S10” manufactured by Toray Industries, Inc.)
Adhesive layer 64 and adhesive layer 65: 17 parts by mass of main agent (A1143 manufactured by Mitsui Chemicals) / 1 part by mass of urethane-based adhesive (A50 manufactured by Mitsui Chemicals)

<Evaluation example>
The adhesive strength after the second resin sheet surface side of the back surface protective sheet and the back surface sealing material sheet composed of the following sealing materials 1 to 3 were vacuum-pressed and laminated at 150 ° C. for 15 minutes was determined according to JIS K6854-3. , And measured as N / 15 mm width under conditions of a substrate width of 15 mm and a peeling speed of 50 mm / min. The heat shrinkage rate was measured by using the heat shrinkage rate after 30 minutes at 150 ° C. according to JIS K7133 as (%) MD (flow direction) and TD (width direction). The results are shown in Table 1.

Sealing material 1 (polyethylene resin without cross-linking agent)
Silane-modified transparent resin: 98 parts by mass of a metallocene linear low density polyethylene (hereinafter referred to as M-LLDPE) having a density of 0.898 g / cm 3 and a melt mass flow rate at 190 ° C. of 2 g / 10 min. On the other hand, 2 parts by mass of vinyltrimethoxysilane and 0.1 part by mass of dicumyl peroxide as a radical generator (reaction catalyst) were mixed and melted and kneaded at 200 ° C. to obtain a silane-modified transparent resin. .
Weatherproof masterbatch: 3.8 parts by mass of benzophenol UV absorber and 5 parts by mass of hindered amine light stabilizer with respect to 100 parts by mass of powder obtained by pulverizing Ziegler linear low density polyethylene with a density of 0.920 g / cm3 Part and 0.5 parts by mass of a phosphorous heat stabilizer were mixed, melted, processed, and pelletized to obtain a master batch.
20 parts by mass of the above silane-modified transparent resin, 5 parts by mass of a weather-resistant masterbatch, and 80 parts by mass of a metallocene linear low density polyethylene having a density of 0.905 g / cm 3 as an additive polyethylene are mixed, φ150 mm extruder, 1000 mm Using a film forming machine having a T-die having a width, a sealing material sheet having a thickness of 400 μm was produced at an extrusion temperature of 230 ° C. and a take-off speed of 2.3 m / min.

Sealing material 2 (polyethylene resin with a crosslinking agent)
Silane modified transparent resin: vinyl trimethoxy with respect to 98 parts by mass of metallocene linear low density polyethylene (M-LLDPE) having a density of 0.881 g / cm ³ and an MFR at 190 ° C. of 2 g / 10 min. and silane 2 parts by mass were mixed and dicumyl peroxide 0.1 part by weight of a radical generator (catalyst), melted at 200 ° C., kneaded, MFR at a density 0.884g ^/ cm 3, 190 ℃ A silane-modified transparent resin having a weight of 1.8 g / 10 min was obtained.
Weatherproof masterbatch: 3.8 parts by mass of benzophenol UV absorber and hindered amine light stabilizer 5 with respect to 100 parts by mass of powder obtained by pulverizing Ziegler linear low density polyethylene having a density of 0.880 g / cm ³ Mass parts and 0.5 parts by mass of a phosphorous heat stabilizer were mixed, melted, processed, and pelletized to obtain a master batch.
Crosslinking agent compound resin 1: 2,5-dimethyl-2,5 as a crosslinking agent with respect to 100 parts by mass of M-LLDPE pellets having a density of 0.880 g / cm ³ and MFR at 190 ° C. of 3.1 g / 10 min. -Compound pellets were obtained by impregnating 0.1 part by weight of di (t-butylperoxy) hexane.
20 parts by mass of the above silane-modified transparent resin, 5 parts by mass of weatherproof masterbatch, and 80 parts by mass of the crosslinker compound resin 1 are mixed and extruded using a film forming machine having a φ30 mm extruder and a 200 mm wide T die. A sealing material sheet having a thickness of 400 μm was produced at a temperature of 210 ° C. and a take-off speed of 1.1 m / min.

Sealing material 3 (polyethylene resin with a crosslinking agent)
100 parts by mass of EVA (vinyl acetate content 28%, manufactured by Mitsui DuPont Polychemical, trade name EVAFLEX / EV250 grade), 1.5 parts by mass of cross-linking agent (Lupersol 101), antioxidant (NAUGARD-P) 0. 2 parts by mass and a UV absorber (0.1 part by mass of Tinuvin 7709 and 0.3 part by mass of Cyasorb UV-531) were used. A 400 μm-thick sealing material sheet was prepared by a T-die method at a film forming temperature of 90 ° C. to 100 ° C.

  As is apparent from the above evaluation results, in Examples 1 and 2 containing modified polyphenylene ether as the second resin sheet, the adhesive strength is high in the case of the sealing materials 2 and 3 containing a crosslinking agent. In addition, even if it is an Example, in the sealing material 1 which does not contain a crosslinking agent, the improvement of adhesive strength is not recognized.

  In Example 1 having a low styrene resin content, the adhesive strength is much higher than that in Example 2, and thermal deformation is also small. For this reason, it can be understood that the back surface protective sheet of Example 1 is particularly suitable.

DESCRIPTION OF SYMBOLS 1 Solar cell module 2 Transparent front substrate 3 Front sealing material sheet 4 Solar cell element 5 Back surface sealing material sheet 6 Back surface protection sheet 61 First resin sheet 62 Second resin sheet 63 Third resin sheet 64 Adhesive layer 65 Adhesive Layer 66 UV shielding material

Claims (2)

A solar cell module in which a multilayer protective sheet, a sealing material sheet, and a solar cell element are laminated,
The multilayer protective sheet is
A weather-resistant first resin sheet made of a fluororesin that is a resin having no aromatic skeleton disposed on the exposed surface side;
A modified polyphenylene containing an aromatic skeleton, which is laminated directly or through another layer on the non-exposed surface side of the first resin sheet, and containing 5% by mass to 10% by mass of a styrene resin A second resin sheet containing ether,
The first resin sheet contains an ultraviolet shielding material, the second resin sheet does not contain an ultraviolet shielding material,
The multilayer protective sheet is disposed so as to be exposed on the back surface of the solar cell module,
The sealing material sheet is an ethylene-vinyl acetate copolymer resin or a polyethylene resin,
The second resin of the multilayer protective sheet is crosslinked between the ethylene-vinyl acetate copolymer-based resin and the modified polyphenylene ether, or crosslinked between the polyethylene-based resin and the modified polyphenylene ether. A solar cell module in which a sheet and the sealing material sheet are directly laminated.   The method for producing a solar cell module according to claim 1, wherein the sealing material sheet is a polyethylene resin, and the content of the crosslinking agent before crosslinking of the polyethylene resin is 0.1% by mass or less.

Images