JP2013041974A - Seal material for solar cell module and solar cell module including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a seal material sheet for a solar cell module, which is an olefin-based seal material for a solar cell module and eliminates trimming process, which is an obstacle for improving productivity, in manufacturing process of solar cell modules, capable of improving the productivity of solar cell modules.SOLUTION: A seal material sheet for a solar cell module contains low-density polyethylene having a density of 0.900 g/cmor less, has a gel fraction of 80% or less, and has a complex viscosity value at a temperature of 100°C or above and 150°C or below of 3.0×10Pa s or greater and 5.0×10Pa s or less. Accordingly, both maintained adhesion and suppressed fluidity can be achieved.

Description

  The present invention relates to a solar cell module sealing material sheet and a solar cell module using the same. More specifically, the sealing sheet for solar cell modules is an olefin-based sealing material sheet that does not require a trimming process for cutting off the side surface of the sealing material sheet when integrated as a solar cell module. The present invention relates to a stop sheet and a solar cell module using the same.

  In recent years, solar cells as a clean energy source have attracted attention due to the growing awareness of environmental issues. Currently, various types of solar cell modules have been developed and proposed. Generally, a solar cell module has a configuration in which a transparent front substrate, a solar cell element, and a back surface protection sheet are laminated via a sealing material sheet.

  As a sealing material sheet filled in the solar cell module and used to protect the solar cell element from external impacts and prevent moisture from entering the solar cell module, ethylene-vinyl acetate copolymer is used. Combined resin (EVA) has been used as the most common, but in recent years, the problem of generation of acetic acid gas, which is a drawback of EVA resin, has been solved, and is equal to or better than EVA resin sealing material sheet. As a material having weather resistance and durability, a sealing material sheet for a solar cell module using a polyolefin-based resin has been proposed (see Patent Document 1).

  On the other hand, when manufacturing a solar cell module, a stacking process in which components including such a sealing material sheet are stacked to form a stacked body, and an integration process in which the stacked body is integrated by vacuum thermal lamination are required. However, in addition, a trimming step of cutting off unnecessary portions of the unnecessary sealing material sheet that protruded to the periphery of the laminated body after the integration step has been essential (see Patent Document 2). And the necessity of this trimming process has been a major obstacle to increasing productivity in the manufacturing process of the solar cell module.

JP 2000-91611 A JP 2001-177126 A

  In the manufacturing process of the solar cell module, in order to eliminate the trimming process that is an obstacle to increasing the productivity, for example, as a sealing material composition, by performing a resin having a high melting point or a crosslinking treatment It is conceivable to use a resin whose fluidity during heat treatment is suppressed. However, when such a sealing material composition is used, the wraparound characteristic with respect to the unevenness of the other constituent members laminated at the time of integration as a solar cell module is lowered, which is required for a solar cell module sealing material sheet. Insufficient adhesion and insulation can be secured. Further, it is conceivable to prevent the sealing material sheet from protruding by lowering the pressure and temperature during lamination, but this method is also not preferable from the viewpoint of adhesion and insulation.

  If the sealing material sheet has high wraparound characteristics and low fluidity, the trimming process is not required in the manufacturing process of the solar cell module while maintaining the physical properties required for the solar cell module sealing material sheet. However, such a sealing material sheet does not yet exist, and a new development of a sealing material sheet having such physical properties has been demanded.

  The present invention has been made in order to solve the above problems, and is a sealing material sheet having adhesion required for a solar cell module sealing material sheet, which is integrated with other constituent members and is a solar cell. An object of the present invention is to provide a solar cell module encapsulant sheet that can eliminate the need for a trimming step when manufacturing a module and can improve the productivity of the solar cell module.

The present inventors are solar cell module sealing material sheets containing low density polyethylene having a density of 0.900 g / cm ³ or less, and have a complex viscosity of 3.0 × 10 ⁴ Pa at 100 ° C. or more and 150 ° C. or less. -By using the solar cell module sealing material sheet that is not less than S and not more than 5.0 × 10 ⁵ Pa · S, it is possible to eliminate the trimming step that has been conventionally required in the production process of the solar cell module. The inventors have found that this is possible and have completed the present invention. More specifically, the present invention provides the following.

(1) It contains a low density polyethylene having a density of 0.900 g / cm ³ or less, a gel fraction is 80% or less, and the value of the complex viscosity at 100 ° C. to 150 ° C. is 3.0 × 10 ⁴ Pa · s or more. It is 5.0 * 10 < ⁵ > Pa * s or less, The sealing material sheet for solar cell modules characterized by the above-mentioned.

  (2) The sealing material sheet for solar cell modules according to (1), wherein the gel fraction is 2% or more and 80% or less.

  (3) The sealing material sheet for solar cell modules according to (2), wherein the gel fraction is 40% or more.

(4) Contains a low density polyethylene having a density of 0.900 g / cm ³ or less, a gel fraction of 80% or less, and a complex viscosity value of from 100 ° C. to 150 ° C. of 3.0 × 10 ⁴ Pa · s or more. 5.0 × 10 ⁵ P or less, a solar cell module in which a solar cell module encapsulant sheet is disposed, wherein an end surface of a side of the solar cell module encapsulant sheet is A solar cell module which is not cut out.

  According to the present invention, a solar cell module sealing material sheet capable of producing a solar cell module having high adhesion between the substrates without undergoing a trimming step, and such a sealing material sheet. By providing a solar cell module using a solar cell module, the production efficiency of the solar cell module can be greatly improved.

It is a cross-sectional schematic diagram which shows the example of the layer structure about the solar cell module using the sealing material sheet of this invention, and the example of the aspect of the end surface of the side. It is a cross-sectional schematic diagram which shows the example of the layer structure about the solar cell module using the conventional sealing material sheet, and the example of the aspect of the end surface of the side. It is a schematic diagram which shows the example of the process of the trimming process which is one process of the manufacturing method of the conventional solar cell module, and the aspect of the end surface of the side. It is a graph which shows the change of the value of the complex viscosity for every temperature of the sealing material sheet of an Example and a comparative example.

  Hereinafter, a sealing material composition (hereinafter also simply referred to as a sealing material composition) used for a solar cell module sealing material sheet according to the present invention, a solar cell module sealing material sheet (hereinafter simply referred to as a sealing material sheet). The solar cell modules will be sequentially described, and then a method for manufacturing the solar cell module will be described.

<Encapsulant composition>
The sealing material composition of this invention contains the low density polyethylene which has a predetermined physical property, and a crosslinking agent in a predetermined ratio. Hereinafter, after describing the essential components, other resins and other components will be described.

[Low density polyethylene]
In the present invention, low density polyethylene (LDPE) having a density of 0.900 g / cm ³ or less, preferably linear low density polyethylene (LLDPE) is used. Linear low density polyethylene is a copolymer of ethylene and α- olefin, in the present invention, within the scope thereof density of 0.900 g / cm ³ or less, preferably 0.890 g / cm ³ within the following ranges More preferably, it is the range of 0.870-0.885 g / cm < ³ >. If it is this range, favorable softness | flexibility and transparency 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 comonomer distribution. For this reason, molecular weight distribution is narrow, it is possible to make it the above ultra-low density, and a softness | flexibility can be provided with respect to a sealing material sheet. As a result of imparting flexibility, the adhesion between the sealing material sheet and the transparent front substrate, the adhesion between the sealing material sheet and the substrate, such as the adhesion between the sealing material sheet and the back surface protection sheet, is increased.

  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. Therefore, even if the sealing material sheet which consists of a sealing material composition of this invention is arrange | positioned between a transparent front substrate and a solar cell element, power generation efficiency hardly falls.

  As the α-olefin of the low density polyethylene, an α-olefin having no branch is preferably used, and among these, 1-hexene, 1-heptene or 1 which is an α-olefin having 6 to 8 carbon atoms is preferable. -Octene is particularly preferably used. When the number of carbon atoms of the α-olefin is 6 or more and 8 or less, the sealing material sheet can be given good flexibility and good strength. As a result, the adhesion between the encapsulant sheet and the substrate is further enhanced.

  The melt mass flow rate (MFR) of the low-density polyethylene is MFR at 190 ° C. and a load of 2.16 kg measured according to JIS-K6922-2 (in the present specification, the measurement value under these measurement conditions is hereinafter referred to as MFR). Is preferably 0.5 g / 10 min or more and 40 g / 10 min or less, and more preferably 6 g / 10 min or more and 40 g / 10 min or less. If it is this range, the fluidity | liquidity of the sealing material sheet | seat will be hold | maintained and the wraparound characteristic with respect to the unevenness | corrugation of the other structural member laminated | stacked can be provided.

  The sealing material composition of the present invention may further contain a silane-modified polyethylene resin. The silane-modified polyethylene resin is obtained by graft-polymerizing an ethylenically unsaturated silane compound as a side chain to linear low-density polyethylene (LLDPE) or the like as a main chain. Since such a graft copolymer has a high degree of freedom of silanol groups that contribute to the adhesive force, it can improve the adhesion of the sealing material sheet to other members in the solar cell module.

  The silane-modified polyethylene resin can be produced, for example, by the method described in JP-A-2003-46105. By using the resin as a component of the sealing material composition of the solar cell module, strength and durability can be obtained. In addition, it has excellent weather resistance, heat resistance, water resistance, light resistance, wind pressure resistance, yield resistance, and other characteristics, and is also affected by manufacturing conditions such as thermocompression bonding for manufacturing solar cell modules. Therefore, it is possible to manufacture solar cell modules having extremely excellent heat-fusibility, stably and at low cost, and suitable for various applications.

  Examples of ethylenically unsaturated silane compounds to be graft polymerized with low density polyethylene include vinyl trimethoxy silane, vinyl triethoxy silane, vinyl tripropoxy silane, vinyl triisopropoxy silane, vinyl tributoxy silane, vinyl tripentyloxy silane, vinyl It is possible to use one or more selected from triphenoxysilane, vinyltribenzyloxysilane, vinyltrimethylenedioxysilane, vinyltriethylenedioxysilane, vinylpropionyloxysilane, vinyltriacetoxysilane, and vinyltricarboxysilane it can.

  The graft amount, which is the content of the ethylenically unsaturated silane compound, is, for example, 0.001 to 15 masses with respect to a total of 100 mass parts of all the resin components in the sealing material composition containing other polyethylene-based resins described later. What is necessary is just to adjust suitably so that it may become a% grade, Preferably, it is about 0.01-5 mass%, Most preferably, it may be about 0.05-2 mass%. In the present invention, when the content of the ethylenically unsaturated silane compound is large, the mechanical strength and heat resistance are excellent. However, when the content is excessive, the tensile elongation and heat-fusibility tend to be inferior.

The content of polyethylene having a density of 0.900 g / cm ³ or less contained in the encapsulant composition is preferably 10% by mass or more and 99% by mass or less, more preferably 50% by mass or more and 99% by mass in the composition. Or less, more preferably 90 to 99% by mass. Other resin may be included as long as the melting point of the sealing material composition is within a range of less than 80 ° C. These may be used, for example, as an additive resin, or may 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 polymerization initiator can be used. Examples of radical polymerization initiators include hydroperoxides such as diisopropylbenzene hydroperoxide and 2,5-dimethyl-2,5-di (hydroperoxy) hexane; di-t-butyl peroxide, t-butyl Cumyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, 2,5-dimethyl-2,5-di (t-peroxy) hexyne-3, etc. Dialkyl 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 pero Ci-2-ethylhexanoate, t-butyl peroxypivalate, t-butyl peroxyoctoate, t-butyl peroxyisopropyl carbonate, t-butyl peroxybenzoate, di-t-butyl peroxyphthalate, 2 , 5-dimethyl-2,5-di (benzoylperoxy) hexane, 2,5-dimethyl-2,5-di (benzoylperoxy) hexyne-3, t-butylperoxy-2-ethylhexyl carbonate Oxyesters; organic peroxides such as methyl 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 It can be mentioned dibutyltin dioctoate, dioctyltin dilaurate, dicumyl peroxide, such a silanol condensation catalyst.

  As content of a crosslinking agent, it is preferable that it is content of 0.02 mass part or more and 2.0 mass parts or less with respect to 100 mass parts of total of all the resin components of a sealing material sheet, More preferably, it is 0.00. The range is 3 parts by mass or more and 1.5 parts by mass or less. By adding 0.3 parts by mass or more of a crosslinking agent, sufficient durability can be imparted to the low-density polyethylene used in the sealing material sheet of the present invention. On the other hand, when the addition amount of the cross-linking agent exceeds 1.5 parts by mass, the progress of cross-linking in the cross-linking process becomes excessive, and the followability to the unevenness of other members at the time of modularization becomes unfavorable.

[Crosslinking aid]
In the present invention, a polyfunctional monomer having a carbon-carbon double bond and / or an epoxy group can be used as a crosslinking aid. More preferably, the cross-linking aid is one in which the functional group of the polyfunctional monomer is an allyl group, a (meth) acrylate group, or a vinyl group. Thereby, in any process until the integration process as a solar cell module is finished, an appropriate crosslinking reaction is promoted, and the gel fraction of the sealing material sheet in a state integrated as a solar cell module is 80. % Or less.

  When the encapsulant sheet of the present invention is a crosslinked encapsulant sheet that has undergone a crosslinking treatment before the integration step as a solar cell module, the above-mentioned carbon-carbon double bond is used as a crosslinking aid. And / or a polyfunctional monomer having an epoxy group. Thereby, an appropriate crosslinking reaction is promoted, and the gel fraction is adjusted to 2% or more and 80% or less.

  In the present invention, the crosslinking aid reduces the crystallinity of the linear low density polyethylene and maintains transparency. Thereby, the crosslinked sealing material sheet excellent in transparency and low temperature flexibility can be obtained.

  Specifically, polyallyl compounds such as triallyl isocyanurate (TAIC), triallyl cyanurate, diallyl phthalate, diallyl fumarate, diallyl maleate, trimethylolpropane trimethacrylate (TMPT), trimethylolpropane triacrylate (TMPTA) Poly (meth) acryloxy compounds such as ethylene glycol diacrylate, ethylene glycol dimethacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, 1,9-nonanediol diacrylate, Glycidyl methacrylate containing epoxy groups, 4-hydroxybutyl acrylate glycidyl ether and 1,6-hexanediol diglycidyl ether containing two or more epoxy groups, 1 4-butanediol diglycidyl ether, cyclohexanedimethanol diglycidyl ether, and epoxy compounds such as trimethylolpropane polyglycidyl ether. These may be used alone or in combination of two or more.

  As content of a crosslinking adjuvant, it is preferable that 0.01-3 mass parts is contained with respect to a total of 100 mass parts of all the resin components of a sealing material sheet, More preferably, 0.05 mass parts- The range is 2.0 parts by mass. Within this range, an appropriate crosslinking reaction can be promoted to make the gel fraction of the crosslinked encapsulant sheet 80% or less. By setting the gel fraction to 80% or less, it is preferable because flexibility equal to or higher than EVA can be obtained in a low temperature range from −50 ° C. to 0 ° C. while having the same degree of transparency as conventional EVA. When the gel fraction exceeds 80%, the flexibility is lowered, and the adhesiveness to glass or the like is not preferable.

[Adhesion improver]
By adding an adhesion improver to the encapsulant composition, it is possible to further improve the adhesion durability with other substrates such as glass. As the adhesion improver, a known silane coupling agent can be used. The silane coupling agent is not particularly limited. For example, vinyl-based silane coupling agents such as vinyltrichlorosilane, vinyltrimethoxysilane, and vinyltriethoxysilane, 3-methacryloxypropyltrimethoxysilane, and 3-methacryloxypropyldiethoxy. A methacryloxy-based silane coupling agent such as silane or 3-methacryloxypropyltriethoxysilane can be preferably used. In addition, these can also be used individually or in mixture of 2 or more types.

  When adding a silane coupling agent as an adhesion improver, the content is 0.1 parts by mass or more and 10.0 parts by mass or less with respect to 100 parts by mass in total of all resin components of the sealing material composition. Yes, and the upper limit is preferably 5.0 parts by mass or less. When the content of the silane coupling agent is in the above range, and the polyolefin resin constituting the encapsulant composition contains an appropriate amount of the ethylenically unsaturated silane compound, the adhesion is more preferable. And improve. In addition, when this range is exceeded, the film-forming property is deteriorated, and the so-called bleed-out in which the silane coupling agent aggregates and solidifies with time and is pulverized on the surface of the sealing material sheet is not preferable.

[Radical absorbent]
The degree of crosslinking can be further finely adjusted by using the above-mentioned crosslinking assistant serving as a radical polymerization initiator in combination with the radical absorbent for quenching it. Examples of such radical absorbents include hindered phenol-based antioxidants, hindered amine-based weather resistance stabilization, and the like. A hindered phenol-based radical absorbent having a high radical absorbing ability near the crosslinking temperature is preferred. It is preferable that the usage-amount of a radical absorber is contained 0.01 mass part-3 mass parts with respect to a total of 100 mass parts of all the resin components of a sealing material sheet, More preferably, 0.05 mass part-2. The range is 0 part by mass.

[Other ingredients]
The sealing material composition may further contain other components. For example, components such as a weather resistance masterbatch for imparting weather resistance to a sealing material sheet produced from the sealing material composition of the present invention, various fillers, a light stabilizer, an ultraviolet absorber, and a heat stabilizer Illustrated. These contents vary depending on the particle shape, density, and the like, but may be within a range of 0.001 to 5 parts by mass with respect to 100 parts by mass in total of all resin components of the encapsulant sheet. preferable. 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 to the encapsulant composition.

  A weatherproof masterbatch is obtained by dispersing a light stabilizer, an ultraviolet absorber, a heat stabilizer and the above-mentioned antioxidant in a resin such as polyethylene, and adding this to a sealing material composition. Thus, good weather resistance can be imparted to the encapsulant sheet. The weatherproof masterbatch may be prepared and used as appropriate, or a commercially available product may be used. The resin used in the weatherproof masterbatch may be a linear low density polyethylene used in the present invention, or other resins described above.

  These light stabilizers, ultraviolet absorbers, heat stabilizers and antioxidants can be used alone or in combination of two or more.

<Sealing material sheet>
The solar cell module sealing material sheet of the present invention is a sheet-like or film-like sealing material sheet obtained by melt-molding the above-described sealing material composition at a temperature exceeding its melting point, and is an olefin-based one. In the encapsulant sheet for solar cell modules using resin, focusing on the complex viscosity of the encapsulant sheet that has not been noticed in the past, the complex viscosity of the encapsulant sheet is limited to a predetermined range. There are features. Specifically, in the sealing material sheet of the present invention, the complex viscosity at 100 ° C. or more and 150 ° C. or less is 3.0 × 10 ⁴ Pa · S or more and 5.0 × 10 ⁵ Pa · S or less. By setting the complex viscosity within this range, it is possible to moderately suppress the fluidity during the thermal laminating process while ensuring the adhesion required for the solar cell module encapsulant sheet and the wraparound characteristic to the unevenness. As a result, unnecessary protrusion of the encapsulant sheet in the integration step as a solar cell module can be prevented, and the trimming step, which has conventionally been an essential step in the manufacture of solar cell modules, can be eliminated. When the complex viscosity is less than 3.0 × 10 ⁴ Pa · s, it is not possible to prevent the sealing material sheet from protruding from the laminated body during the heat laminating process performed in the integration process as a solar cell module, and trimming is performed. A process is essential. If it exceeds 5.0 × 10 ⁵ Pa · s, the wraparound characteristic with respect to the irregularities during the heat laminating process becomes insufficient, and the adhesion and insulation properties deteriorate, which is not preferable.

  Here, the complex viscosity (Pa · s) is a rotational rheometer (MCR301 manufactured by Anton Paar), parallel plate geometry (diameter 8 mm), stress 0.5 N, strain 5%, angular velocity 0.1 ( 1 / s), which is a complex viscosity.

  The sealing material sheet of the present invention is not particularly limited as to whether or not the crosslinking treatment is performed in the stage after the melt formation of the sealing material sheet, but after the melt formation, as a solar cell module It is preferable that it is the bridge | crosslinking sealing material sheet which gave the crosslinking process before the integration process. This is because the cross-linked encapsulant sheet can suppress the flow in the heat laminating step even if a low-density polyethylene as a base has a high MFR.

  The gel fraction of the encapsulant sheet of the present invention is 80% or less, and particularly for the crosslinked encapsulant sheet, the gel fraction is 2% or more and 80% or less. When the gel fraction is within these ranges, the sealing property to the unevenness can be maintained well. In addition, since the dimensional stability at the time of shaping | molding can be made very high by making a gel fraction into 40% or more, the protrusion of the unnecessary part of the sealing material sheet in the process of integrating a solar cell module is extremely Can be small.

  Here, the gel fraction (%) means that 0.1 g of a sealing material sheet is put in a resin mesh, extracted with 60 ° C. toluene for 4 hours, taken out together with the resin mesh, weighed after drying, and mass before and after extraction. Comparison is made to measure the mass% of the remaining insoluble matter, and this is used as the gel fraction.

  In addition, when the average MFR of all the base resins contained in the sealing material composition is 6 g / 10 min or less, the gel fraction is 25% or more, even if it is less than 40%, It is also possible to increase the dimensional stability of to the required level. Thus, the obtained sealing material sheet can also make the protrusion of the unnecessary part of the sealing material sheet in the process of integrating the solar cell module extremely small.

<Method for producing sealing material sheet>
[Sheet making process]
The melt molding of the sealing material composition is carried out 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. At that time, the lower limit of the molding temperature may be a temperature exceeding the melting point of the encapsulant composition, and the upper limit is a temperature at which crosslinking does not start during extrusion film formation, depending on the 1-minute half-life temperature of the crosslinking agent used. There is no particular limitation as long as it is within these ranges. By this step, an uncrosslinked sealing material sheet can be obtained.

[Crosslinking process]
As a solar cell module that integrates the sealing material sheet with another member after the completion of the sheeting step, a crosslinking treatment step of performing a crosslinking treatment on the uncrosslinked sealing material sheet after the sheeting step. By doing it before the start of the integration process. A crosslinked encapsulant sheet can be obtained. The gel fraction of the crosslinked encapsulant sheet is 2% or more and 80% or less.

  The cross-linking step is preferably heat treatment, but is not limited thereto, and may be cross-linking treatment using electromagnetic waves such as UV (ultraviolet rays) and EB (electron beams). In the case of heat treatment, the individual crosslinking conditions are not particularly limited, and may be set as appropriate so that the gel fraction is the total treatment result within the range of general crosslinking treatment conditions. Note that when the crosslinking treatment is a heat treatment, it may also serve as an annealing treatment. In addition, a bridge | crosslinking process may be performed in-line continuously following a sheet forming process, and may be performed off-line.

  In addition, the crosslinking treatment before the step of integrating the solar cell module is not necessarily essential, and the uncrosslinked sealing material sheet using the sealing material composition described above is crosslinked in the integration step as the solar cell module. May be.

<Solar cell module>
FIG. 1: is sectional drawing which shows the example of the layer structure about the solar cell module of this invention, and the example of the aspect of the end surface of the side. In the solar cell module 1, a transparent front substrate 2, a front sealing material layer 3, a solar cell element 4, a back sealing material layer 5, and a back surface protection sheet 6 are sequentially laminated from the light receiving surface side of incident light.

  The solar cell module 1 uses the sealing material sheet of the present invention as the front sealing material layer 3 and the back sealing material layer 5, thereby eliminating the need for a trimming process in the manufacturing process. Therefore, after being integrated as the solar cell module 1, the end face 8 on the side of the sealing material sheet constituting the front sealing material layer 3 and the back sealing material layer 5 is not cut off. To do.

  Since the solar cell module 1 has not undergone the trimming process, as shown in FIGS. 1A to 1C, the end face 8 on the side of the encapsulant sheet is not flattened and has minute unevenness. It has become. However, the unevenness is minute so as not to substantially affect the adhesion performance and design properties of the solar cell module, and the solar cell module 1 has preferable physical properties required for the solar cell module such as adhesion. The productivity is greatly improved while maintaining.

  Here, when manufacturing a solar cell module using a conventionally known sealing material sheet, it has been essential to go through a trimming step. As a specific example of the aspect of the end face 8 on the side of the sealing material sheet of the conventional solar cell module 10 in which it is essential that “the end face on the side of the sealing material sheet is cut off”, FIG. The aspect of-(C) can be mentioned. FIG. 2 (A) shows a case where a trimming process is necessary because the protruding part of the encapsulant sheet has a high fluidity and hangs down on the other member side laminated on the lower surface. The trimming process is necessary because the change in the stop sheet is large, and if the size of the encapsulant sheet before modularization is reduced in consideration of the change, a gap will be created and a problem will occur in the sealing performance. In some cases, FIG. 2C shows that the shape of the encapsulant sheet changes, but the fluidity is low and does not hang down to other members laminated on the lower surface. In this case, the trimming process is necessary.

  In the case shown in FIGS. 2A to 2C, as shown in FIG. 3A, a trimming step for performing a cutting process of cutting off the protruding portion of the sealing material sheet by the cutting means 7 such as a scraper is essential. In addition, in the conventional solar cell module 10 manufactured through the trimming process, as shown in FIG. 3B, the end surface 8 on the side of the sealing material sheet is flattened by cutting. It has become.

  On the other hand, as a specific example of the aspect of the end face of the solar cell module 1 of the present invention “the end face of the side edge of the sealing material sheet is not cut off”, the aspects of FIGS. be able to. In FIG. 1A, when the trimming process is unnecessary because the change in the shape of the encapsulant sheet is extremely small, the shape of the encapsulant sheet changes slightly in FIG. In the case where the trimming process can be made unnecessary by forming the size of the sealing material sheet before modularization slightly smaller in consideration of the change, FIG. 1 (C) shows the sealing. When the shape of the material sheet changes slightly, but does not hang down on the other member side laminated on the lower surface, and the change in shape does not hinder the mounting of the external frame, etc., and the trimming process can be eliminated It is.

  The solar cell module 1 of the present invention manufactured without going through the trimming process is characterized in that the end face 8 of the sealing material sheet is not flattened by the trimming process. Even if the aspect of the end face 8 on the side of the encapsulant sheet is any of the three aspects shown in FIGS. 1 (A) to (C), or other aspects, As long as the trimming step is not required by limiting the composition of the encapsulant sheet to the range of the present invention, it is within the scope of the present invention regardless of the specific shape of the end face.

  In the solar cell module 1 of the present invention, the transparent front substrate 2, the solar cell element 4, and the back surface protection sheet 6, which are members other than the front sealing material layer 3 and the back sealing material layer 5, are conventionally known. Things can be used without particular limitation. Moreover, the solar cell module 1 of this invention may also contain members other than the said member.

<Method for manufacturing solar cell module>
Below, the manufacturing method of the solar cell module of this invention is demonstrated. The solar cell module 1 is, for example, a laminated body in which the transparent front substrate 2, the front sealing material layer 3, the solar cell element 4, the back sealing material layer 5, and the back protection sheet 6 are sequentially stacked. (Hereinafter, also simply referred to as a laminate) can be manufactured through a heat laminating step of thermocompression forming as an integrally formed body by a molding method such as a thermal lamination method.

  Here, in the conventional manufacturing method, as shown in FIG. 3, the sealing material sheet that protrudes from the peripheral portion of the laminate due to melting and expansion of the sealing material sheet in the thermal laminating process following the thermal laminating process. A trimming process for excising unnecessary portions was essential. Actually, assuming that unnecessary portions are to be cut off, transparent front substrate 2 and back surface protective sheet 6 having a larger area than the completed area are laminated in advance, and unnecessary portions of the encapsulant sheet after the lamination process In addition, there has been widely used a manufacturing method in which unnecessary portions of the transparent front substrate 2 and the back surface protection sheet 6 are simultaneously cut to obtain a solar cell module of a desired size. This has been an obstacle to increasing the production efficiency of solar cell modules.

  In the production of the solar cell module of the present invention, the trimming step is not required by using the sealing material sheet of the present invention as the front sealing material layer 3 and the back sealing material layer 5. This greatly improved the production efficiency of the solar cell module.

  While the present invention has been specifically described with reference to the embodiment, the present invention is not limited to the above embodiment, and can be implemented with appropriate modifications within the scope of the present invention.

EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to a following example.
<Manufacture of sealing material sheet>
The components of each composition shown in Table 1 below are mixed and melted in units of parts by mass to form each encapsulant composition, and each encapsulant composition has a thickness of 400 to 480 μm by a conventional T-die method. To form an uncrosslinked sealing material sheet. The film forming temperature was 90 ° C. or higher and lower than 100 ° C.
LLDPE1 (base resin M1): a metallocene linear low-density polyethylene which is a copolymer of ethylene and 1-hexene and has a density of 0.880 g / cm ³ and MFR of ³⁰ g / 10 min.
LLDPE2 (base resin M2): a metallocene linear low-density polyethylene which is a copolymer of ethylene and 1-hexene and has a density of 0.880 g / cm 3 and MFR 3.1 g / 10 min.
Silane-modified polyethylene resin (base resin S1): a copolymer of ethylene and 1-hexene, a metallocene linear low-density polyethylene resin having a density of 0.880 g / cm 3 and an MFR of 8 g / 10 min, 98 parts by mass 2 parts by weight of vinyltrimethoxysilane and 0.1 part by weight of dicumyl peroxide as a radical generator (reaction catalyst) were mixed, melted and kneaded at 200 ° C., with a density of 0. A silane-modified polyethylene resin having 884 g / cm ³ and MFR 6.0 g / 10 min.
Silane-modified polyethylene resin 2 (base resin S2): metallocene linear low-density polyethylene resin having a density of 0.881 g / cm ³ and an MFR of 2 g / 10 min at 190 ° C., 98 parts by mass , 2 parts by mass of vinyltrimethoxysilane and 0.1 part by mass of dicumyl peroxide as a radical generator (reaction catalyst) were mixed, melted at 200 ° C., and kneaded to obtain a density of 0.884 g / cm 3. ^3. A silane-modified polyethylene resin having an MFR of 1.8 g / 10 min.
Cross-linking agent 1 (labeled as cross-linking 1 in Table 1): t-butylperoxy-2-ethylhexyl carbonate (manufactured by Arkema Yoshitomi Co., Ltd., trade name Luperox TBEC)
Cross-linking agent 2 (labeled as cross-linking 2 in Table 1): 2,5-dimethyl-2,5-di (t-butylperoxy) hexane (manufactured by Arkema Yoshitomi, trade name Luperox 101)
Crosslinking aid (labeled as support in Table 1): triallyl isocyanurate (product name SR533, manufactured by Statomer)
UV absorber (labeled UV in Table 1): Chemipro Kasei Co., Ltd., trade name KEMISORB12
Weather stabilizer (labeled as weather resistance in Table 1): Ciba Japan Co., Ltd., trade name Tinuvin 770
Antioxidant (labeled as acid protection in Table 1): Ciba Japan Co., Ltd., trade name Irganox 1076

About each uncrosslinked sealing material sheet | seat of Examples 1, 3 and Comparative Examples 1-3, the crosslinking process was given on the following conditions, respectively, and the crosslinked sealing material sheet was obtained. In Example 2, the cross-linking treatment was not performed and the uncrosslinked encapsulant sheet was left as it was.
Example 1: Cross-linking treatment by oven at a cross-linking temperature of 220 ° C. and a cross-linking time of 2.5 minutes. Example 3: Accelerating voltage of 200 kV using an electron beam irradiation apparatus (product name EC250 / 15 / 180L, manufactured by Iwasaki Electric Co., Ltd.) Crosslinking treatment by irradiation on both sides with irradiation intensity of 4.5 Mrad and irradiation with a total of 10 Mrad Comparative Example 1: Crosslinking treatment with oven at a crosslinking temperature of 220 ° C. and a crosslinking time of 2.0 minutes Comparative Example 2: Crosslinking temperature of 200 ° C. Crosslinking treatment by oven at a crosslinking time of 2.0 minutes Comparative Example 3: Crosslinking treatment by oven at a crosslinking temperature of 240 ° C. and a crosslinking time of 4.0 minutes

  The result of having measured the gel fraction of each sealing material sheet of Examples 1-3 and Comparative Examples 1-3 was as Table 2 below.

Moreover, about each sealing material sheet of Examples 1-3 and Comparative Examples 1-3, the complex viscosity was measured by the following method in the range of 70 to 150 degreeC. The results are shown in FIG.
[Test method for complex viscosity]
Complex viscosity is measured using a rotary rheometer (MCR301 manufactured by Anton Paar) under the conditions of parallel plate geometry (diameter 8 mm), stress 0.5 N, strain 5%, angular velocity 0.1 (1 / s). did.

<Evaluation Example 1>
The laminated body which laminated | stacked the sealing material sheet | seat of Examples 1-3 and Comparative Examples 1-3 cut into the same size between two glass substrates (blue plate glass 150mm * 150mm * 3.0mm) is vacuum-heated. A laminator was pressurized at 100 ° C. at 150 ° C. for 18 minutes, integrated by heat lamination, and solar cell module evaluation samples were obtained for the respective examples and comparative examples. About these samples for solar cell module evaluation, the presence or absence of the protrusion of the unnecessary part of a sealing material sheet was evaluated on the following test conditions. The results are shown in Table 3.
[Test method for presence or absence of protrusion of unnecessary part of encapsulant sheet]
In the solar cell module evaluation sample, the portion of the encapsulant sheet protruding from each side of the glass substrate is observed, and a part of the encapsulant is exposed at a maximum width of 3 mm or more from the end of the glass substrate. And those in which a part of the sealing material hangs down along the end face of the glass substrate were evaluated as “extruding”, and the others were evaluated as “no protruding”.

<Evaluation Example 2>
The sealing material sheets of Examples 1 to 3 and Comparative Examples 1 to 3 cut to a width of 15 mm on a glass substrate (white plate semi-tempered glass 3KWE33 75 mm × 50 mm × 3.2 mm) made of textured glass with irregularities on the surface. The laminated body was processed with a vacuum heating laminator at 150 ° C. for 18 minutes to obtain solar cell module evaluation samples for each of the examples and comparative examples. About the sample for solar cell module evaluation, the adhesiveness in the following test conditions was evaluated. The results are shown in Table 3.
[Adhesion test method]
Peeling test: In the above solar cell module evaluation sample, a vertical peeling (50 mm / min) test is performed on a sealing material sheet in close contact with a glass substrate using a peeling tester (Tensilon Universal Tester RTF-1150-H). The adhesion strength was measured.

  From Table 2 and FIG. 3, the sealing material sheets of Examples 1 to 3 having a complex viscosity in a specific range have sufficient adhesion strength even with uneven glass, and are sealed for solar cell modules. As a material, it has a sufficiently preferable adhesiveness in consideration of the wraparound characteristic to the unevenness. And it turns out that the sealing material sheet of Examples 1-3 does not require a trimming process in the process of integration as a solar cell module. In Comparative Examples 1 and 2 where the complex viscosity value is not within the preferred range, the trimming step is essential, and in Comparative Example 3 having a high gel fraction, the trimming step is unnecessary, but the adhesion may be insufficient. I understand.

DESCRIPTION OF SYMBOLS 1 Solar cell module 2 Transparent front substrate 3 Front sealing material layer 4 Solar cell element 5 Back surface sealing material layer 6 Back surface protection sheet 8 End surface of the side of sealing material sheet

Claims (4)

Containing low density polyethylene with a density of 0.900 g / cm ³ or less,
The gel fraction is 80% or less,
A sealing material sheet for a solar cell module, wherein a complex viscosity value at 100 ° C. to 150 ° C. is 3.0 × 10 ⁴ Pa · s or more and 5.0 × 10 ⁵ Pa · s or less.   The encapsulant sheet for a solar cell module according to claim 1, wherein the gel fraction is 2% or more and 80% or less.   The sealing material sheet for solar cell modules according to claim 2, wherein the gel fraction is 40% or more. Containing low density polyethylene with a density of 0.900 g / cm ³ or less,
The gel fraction is 80% or less,
The solar cell on which a sealing material sheet for a solar cell module is disposed, wherein a complex viscosity value at 100 ° C. to 150 ° C. is 3.0 × 10 ⁴ Pa · s or more and 5.0 × 10 ⁵ P or less. A battery module,
The solar cell module, wherein an end surface of a side edge of the solar cell module sealing material sheet is not cut.

Images