JP2014093477A - Sealing material composition for solar cell module - Google Patents

Abstract

Provided is a composition for a polyethylene-based resin-based encapsulant sheet used in a solar cell module in combination with a cross-linking agent, which is excellent in the effect of suppressing protrusion in a vacuum heat laminating process. .
A polyethylene resin (A) having an MFR of 25 g / 10 min to 40 g / 10 min, a polyethylene resin (B) having an MFR of 1 g / 10 min to 3 g / 10 min, and a crosslinking agent (C Is a sealing material sheet obtained by melt-molding a composition having a mass ratio of the polyethylene resin (A) and the polyethylene resin (B) of 90:10 to 75:25. At this time, the polyethylene resin (B) having a relatively low MFR exhibits a flow suppressing effect and can solve the above problem.
[Selection] Figure 1

Description

  The present invention relates to a sealing material composition for a solar cell module and a sealing material sheet 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.

  Each member constituting the solar cell module or the like is always exposed to a harsh environment such as strong ultraviolet rays, heat rays, wind and rain. For this reason, each member which comprises a solar cell module needs to be equipped with durability over a long period of time on these conditions.

  As a constitution of the sealing material composition for providing the solar cell module sealing material with such durability, EVA (ethylene-vinyl acetate copolymer) is used as a base resin, a crosslinking agent and a crosslinking auxiliary agent. Is known (see Patent Document 1). In this case, the above composition is generally heated at a low temperature of 50 ° C. to 90 ° C. because if the crosslinking reaction proceeds during extrusion molding, the load during molding becomes excessive and the productivity decreases or becomes impossible to mold. Extruded to form uncrosslinked. And it is what is called a thermosetting type sealing material sheet | seat which bridge | crosslinks after shaping | molding or is bridge | crosslinked by the heating in the case of modularization.

  As such a thermosetting type sealing material sheet, in particular, a polyethylene-based resin-based sealing sheet has been studied recently. For example, in the following Patent Document 2, the MFR is 6 g / 10 min or more and 40 g / 10 min or less. A low-density polyethylene is used as a base resin, and a composition containing a crosslinking agent and a crosslinking aid is formed at around 100 ° C. to obtain an uncrosslinked sealing material sheet. Discloses a thermosetting type polyethylene-based encapsulant sheet that undergoes cross-linking.

JP 2009-135200 A JP 2012-54521 A

  When the polyethylene-type resin used as the base resin of the polyethylene-based thermosetting sealing material sheet described in Patent Document 2 is viewed from the viewpoint of MFR, there are the following conflicting problems. The low MFR has few terminal double bonds, and the crosslinking speed is slow, so that the crosslinking is insufficient, or the crosslinking is slow. As a result, the lamination time becomes long and problems such as protrusion occur. In addition, when a low MFR material is used as a thermosetting type, there is an upper limit in the extrusion temperature for extrusion by an uncrosslinked reaction, which increases the mechanical load. On the other hand, when high MFR is selected as the base resin in order to avoid this problem, the fluidity of the resin itself becomes high, so that problems such as protrusion during lamination also occur.

  As described above, there is a problem that even if the MFR of the polyethylene resin as the base resin is high or low, it is not possible to effectively suppress the change in film thickness and the protrusion during modularization.

  The present invention has been made in view of the above situation, and a composition capable of improving flow suppression in a vacuum heat laminating process while using a polyethylene-based resin containing a crosslinking agent, and a sealing material using the same It is an object to provide a sheet.

  The present inventors have found that by using two types of polyethylene resins having different MFRs, the flow suppression in the vacuum heat laminating process can be improved while improving the degree of crosslinking by the crosslinking agent. It came to be completed. More specifically, the present invention provides the following.

(1) A polyethylene resin (A) having an MFR of 190 g and a load of 2.16 kg measured in accordance with JIS K7210 at 25 g / 10 min to 40 g / 10 min,
A polyethylene resin (B) having an MFR of 190 g and a load of 2.16 kg measured in accordance with JIS K7210 and having a load of 2.16 kg of 1 g / 10 min to 3 g / 10 min;
A crosslinking agent (C),
The sealing material composition for solar cell modules whose mass ratio of the said polyethylene-type resin (A) and the said polyethylene-type resin (B) is 90:10 to 75:25.

(2) The encapsulant composition according to (1), wherein each of the polyethylene resin (A) and the polyethylene resin (B) is a linear low density polyethylene having a density of 0.900 g / cm ³ or less.

  (3) The sealing according to (1) or (2), wherein the polyethylene resin (A) and / or the polyethylene resin (B) is a silane-modified polyethylene resin obtained by graft polymerization of an ethylenically unsaturated silane compound. Stopping material composition.

  (4) The sealing material composition according to any one of (1) to (3), wherein the polyethylene resin (B) is a silane-modified polyethylene resin obtained by graft polymerization of an ethylenically unsaturated silane compound.

  (5) The encapsulant composition according to (3) or (4), wherein a graft amount of the ethylenically unsaturated silane compound with respect to 100 parts by mass of the resin component is 0.001 to 15 parts by mass.

  (6) A sealing material sheet for a solar cell module obtained by melt-molding the sealing material composition according to any one of (1) to (5).

(7) Polyethylene resin (A) having a density of 0.900 g / cm ³ or less and an MFR of 190 g and a load of 2.16 kg measured in accordance with JIS K7210 at 25 g / 10 min to 40 g / 10 min ,
A polyethylene resin (B) having a density of 0.900 g / cm ³ or less and an MFR measured at 190 ° C. and a load of 2.16 kg measured in accordance with JIS K7210 is 1 g / 10 min or more and 3 g / 10 min or less. And
The mass ratio of the polyethylene resin (A) and the polyethylene resin (B) is 90:10 to 75:25,
The number average molecular weight derived from the polyethylene resin (A) is 50,000 or more and 70,000 or less,
The sealing material sheet for solar cell modules whose number average molecular weight derived from the said polyethylene-type resin (B) is 8.5-130,000.

  According to the present invention, while using a polyethylene-based resin containing a crosslinking agent, a composition that has low fluidity in a vacuum heat laminating step and can improve the problem of film thickness reduction and protrusion of the sealing material sheet, and the same are used. A sealing material sheet can be provided.

It is sectional drawing which shows an example of the laminated constitution of the solar cell module of this invention.

  Hereinafter, it demonstrates in detail in order of the sealing material composition for solar cell modules of this invention, the sealing material for solar cell modules, and a solar cell module.

<Sealant composition for solar cell module>
First, the sealing material composition of this invention is demonstrated. The sealing material composition is used for melt extrusion molding to obtain a sealing material sheet for a solar cell module. The encapsulant composition contains at least two types of polyethylene resins having different MFRs and a crosslinking agent, and specifically, a polyethylene resin (A) having an MFR of 25 g / 10 min to 40 g / 10 min. And 1 g / 10 min or more and 3 g / 10 min or less of a polyethylene resin (B) and a crosslinking agent (C).

  The polyethylene resin (A) and / or (B) may be a silane-modified polyethylene resin obtained by graft polymerization of an ethylenically unsaturated silane compound.

[Polyethylene resin (A) (B)]
The silane-modified polyethylene resin used in the sealing material composition of the present invention may be low-density polyethylene (LDPE) in addition to LLDPE that satisfies the above conditions, but preferably has a density of 0.900 g. It is a linear low density polyethylene of / cm ³ or less.

  As the linear low density polyethylene which is an ethylene-α olefin copolymer, a metallocene linear low density polyethylene can be preferably used. 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 low density as mentioned above, and a softness | flexibility can be provided with respect to a sealing material. As a result of the flexibility imparted to the sealing material, the adhesion between the sealing material and a transparent front substrate such as glass can be enhanced.

  Metallocene-based linear low density polyethylene has a narrow crystallinity distribution and uniform crystal size, so that not only large crystal size does not exist, but also the crystallinity itself is low due to low density. For this reason, it is excellent in transparency when processed into a sheet shape. Therefore, even if the sealing material 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 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 number of carbon atoms of the α-olefin is 6 or more and 8 or less, the sealing material can be given good flexibility and good strength. As a result, the adhesion between the sealing material and the transparent front substrate such as glass is further enhanced.

[MFR of polyethylene resin (A) (B)]
The MFR of the polyethylene resin (A) is 25 g / 10 min or more and 40 g / 10 min or less, preferably 25 g / 10 min or more and 30 g / 10 min or less. The MFR of the polyethylene resin (B) is 1 g / 10 min or more and 3 g / 10 min or less, preferably 1 g / 10 min or more and 2 g / 10 min or less. Here, MFR is a value at 190 ° C. and a load of 2.16 kg measured according to JIS K7210.

  The sealing material composition of this invention contains a crosslinking agent. For this reason, it is preferable from a crosslinkable point that there are many bridge | crosslinking ends (terminal double bond) used as the crosslinking point of base resin. In view of this point, in the present invention, a polyethylene resin (A) having a high MFR is used. If the MFR is less than 25 g / 10 minutes, it is not preferable because uncrosslinked film formation is difficult and the cross-linking rate is slow, and if it exceeds 40 g / 10 minutes, the protrusion during vacuum lamination and the change in film thickness increase. Absent. The polyethylene resin (A) is preferably 50,000 to 70,000 in terms of number average molecular weight.

  On the other hand, the above-mentioned high MFR polyethylene resin (A) has high fluidity in the first place, and therefore, with the polyethylene resin (A) alone, the film thickness of the encapsulant sheet decreases or protrudes in the vacuum heat laminating process of the encapsulant sheet. Problems occur. For this reason, in this invention, MFR uses together the polyethylene-type resin (B) of 1 g / 10min or more and 3 g / 10min or less. The polyethylene resin (B) is preferably 85000 to 130,000 in terms of number average molecular weight. The polyethylene resin (B) having a relatively low MFR relative to the polyethylene resin (A) exhibits a filler effect in the composition and exhibits a fluidity suppressing effect. Such a low MFR resin having an MFR of 3 g / 10 or less has not been conventionally used in combination with a high MFR resin in the following blending amount, which is a novel feature of the composition of the present invention.

  The mass ratio of the polyethylene resin (A) and the polyethylene resin (B) is 90:10 to 75:25. If the ratio of the polyethylene resin (B) is less than 10, the filler effect is insufficient and the flow suppressing effect cannot be obtained. If the ratio of the polyethylene resin (B) exceeds 25, the film forming property is lowered, which is not preferable. .

[Silane-modified polyethylene resin]
The polyethylene resin (A) and / or the polyethylene resin (B) is preferably a silane-modified polyethylene resin obtained by graft polymerization of an ethylenically unsaturated silane compound, more preferably a polyethylene resin having a relatively low MFR. (B) is preferably a silane-modified polyethylene resin obtained by graft polymerization of an ethylenically unsaturated silane compound. This is because the MFR is lowered due to the crosslinking of the base polyethylene itself due to the grafting operation itself.

  The silane-modified polyethylene resin is obtained by graft polymerization of a polyethylene resin as a main chain with an ethylenically unsaturated silane compound as a side chain. Since such a graft copolymer has a high degree of freedom of silanol groups that contribute to the adhesive force, the adhesion of the sealing material to other members in the solar cell module can be improved. Moreover, the storage stability as a sealing material sheet improves by making it graft compared with the monomer-type silane coupling agent which is easy to deactivate and has low compatibility with a polyethylene-type resin.

  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 the ethylenically unsaturated silane compound to be graft-polymerized include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltripropoxysilane, vinyltriisopropoxysilane, vinyltributoxysilane, vinyltripentyloxysilane, vinyltriphenoxysilane, One or more selected from vinyltribenzyloxysilane, vinyltrimethylenedioxysilane, vinyltriethylenedioxysilane, vinylpropionyloxysilane, vinyltriacetoxysilane, and vinyltricarboxysilane can be used.

  The graft amount, which is the content of the ethylenically unsaturated silane compound, is, for example, 0.001 to 15 mass with respect to a total of 100 mass parts of all the resin components in the sealing material composition containing other polyolefin-based resin described later. Part, preferably 0.01 to 5 parts by mass, particularly preferably 0.05 to 2 parts by 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 density of the silane-modified polyethylene resin is preferably in the range of 0.870 to 0.900 g / cm ³ , and preferably in the range of 0.875 to 0.890 g / cm ³ . By using a low-density resin in this way, it is possible to increase the transparency as compared with a conventional sealing material made of a polyethylene resin, and each member constituting the solar cell module, particularly glass. Adhesion between the transparent front substrate and the sealing material can be remarkably enhanced.

[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.

  The sealant composition of the present invention performs melt extrusion molding at 100 ° C. or lower. For this reason, among the above crosslinking agents, those having a one-minute half-life temperature of 150 ° C. or higher are preferably used.

  As content of a crosslinking agent, it is preferable that it is content of 0.5 mass part or more and 2.0 mass parts or less with respect to the total 100 mass parts of all the resin components of a sealing material, More preferably, it is 0.5. The range is not less than 1.5 parts by mass. By adding a crosslinking agent in this range, sufficient durability can be imparted to the low-density polyethylene resin used for the sealing material of the present invention.

[Crosslinking aid]
In the sealing material composition of the present invention, the crosslinking aid is not an essential component, but can be appropriately used as necessary. Here, the crosslinking assistant is, for example, a polyfunctional vinyl monomer and / or a polyfunctional epoxy monomer, and specifically, triallyl isocyanurate (TAIC), triallyl cyanurate, diallyl phthalate, diallyl fuma. Polyallyl compounds such as rate and diallyl maleate, trimethylolpropane trimethacrylate (TMPT), trimethylolpropane triacrylate (TMPTA), ethylene glycol diacrylate, ethylene glycol dimethacrylate, 1,4-butanediol diacrylate, 1,6 -Poly (meth) acryloxy compounds such as hexanediol diacrylate and 1,9-nonanediol diacrylate, glycidyl methacrylate containing double bond and epoxy group, 4-hydroxybutyl acrylate glycol Epoxy compounds such as 1,6-hexanediol diglycidyl ether, 1,4-butanediol diglycidyl ether, cyclohexane dimethanol diglycidyl ether, trimethylolpropane polyglycidyl ether and the like containing two or more diyl ethers and epoxy groups Can be mentioned.

  In the case where a crosslinking aid is used, among the above, the compatibility with low-density polyethylene is good, the crystallinity is lowered by crosslinking, the transparency is maintained, and TAIC is provided from the viewpoint of imparting flexibility at low temperature. It can be preferably used. Further, 1,6-hexanediol diacrylate can also be preferably used from the viewpoint of reactivity with the silane coupling agent. Further, addition of an appropriate amount of a crosslinking aid to the encapsulant composition can lower the crystallinity of the linear low density polyethylene and maintain higher transparency.

[Other ingredients]
The sealing material composition of the present invention can further contain other components. For example, a weather-resistant masterbatch for imparting weather resistance to a sealing material sheet for a solar cell module produced from the sealing material composition of the present invention, various fillers, a light stabilizer, an ultraviolet absorber, and heat stability Ingredients such as agents 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 mass% in the encapsulant composition. By including these additives, it is possible to impart a long-term stable mechanical strength, an effect of preventing yellowing, cracking, and the like to the encapsulant composition for solar cell modules.

  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. Thereby, favorable weather resistance can be provided to the sealing material sheet for solar cell modules. 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.

  Furthermore, as other components used in the sealing material composition of the present invention, in addition to the above, an adhesion improver such as a silane coupling agent, a nucleating agent, a dispersing agent, a leveling agent, a plasticizer, an antifoaming agent, a difficulty A flame retardant etc. can be mentioned.

[Encapsulant sheet]
The encapsulant sheet for the solar cell module of the present invention is obtained, for example, by molding a encapsulant composition that satisfies the above conditions by a conventionally known method, and is in the form of a sheet or film. Is. In addition, the sheet form in this invention means the film form, and there is no difference in both.

  The sealing material composition is formed into a sheet by various molding methods such as injection molding, extrusion molding, hollow molding, compression molding, and rotational molding, which are used in ordinary thermoplastic resins. Thus, by forming the sealing material composition into a sheet, as the sealing material of the present invention, a sealing material that is a single-layer or multilayer sheet obtained by forming the sealing material composition into a sheet is obtained.

  The sealing material may be a single layer sheet or a multilayer sheet. In the case of a multilayer sheet, the encapsulant composition of the present invention contains a silane-modified polyethylene resin in the re-outer layer on the interface side with the transparent front substrate 2 in order to improve the adhesion to the transparent front substrate 2. It is preferable that an adhesion reinforcing layer is disposed. In this case, for example, the sealing material may have a two-layer structure, and the adhesion reinforcing layer may be disposed only on one layer, or the adhesion reinforcing layer may be disposed on at least one outermost layer with a core layer interposed therebetween. May be.

  In addition, the sealing material of this invention shape | molds with a non-bridge | crosslinking by limiting a shaping | molding temperature to the low temperature range of 90 to 100 degreeC. The cross-linking treatment is performed separately after molding, or the cross-linking is completed by heating at a high temperature at the time of manufacturing a solar cell module described later.

  Moreover, it is preferable that the gel fraction of the adhesion reinforcement layer of the single-layer sealing material and the multilayer sealing material after the completion of the crosslinking is 95% or less. As described above, by adjusting the composition and amount of the crosslinking agent, crosslinking assistant, and other additives to a preferable range, the crosslinking reaction can be appropriately suppressed so that the gel fraction is in the above range. As a result, while having an olefin water vapor barrier, it is more flexible in the low temperature region than EVA, and can also have heat resistance at high temperatures, while being moldable in the low temperature region while being olefinic. Also, an excellent sealing material can be obtained.

  The sealing material sheet of the present invention thus obtained has a number average molecular weight derived from the polyethylene resin (A) of 50,000 to 70,000 and a number average molecular weight derived from the polyethylene resin (B) of 8 .5 or more and 130,000 or less. This molecular weight can be observed as two molecular weight peaks by a conventionally known GPC method or the like.

<Solar cell module>
FIG. 1 is a cross-sectional view showing an example of the layer structure of the solar cell module of the present invention. In the solar cell module 1 of the present invention, a transparent front substrate 2, a front sealing material 3, a solar cell element 4, a back sealing material 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 of the present invention uses the sealing material of the present invention as the front sealing material 3 and / or the back sealing material 5.

  For example, the solar cell module 1 is formed by sequentially stacking the members including the transparent front substrate 2, the front sealing material 3, the solar cell element 4, the back sealing material 5, and the back surface protection sheet 6, and then vacuum suction or the like. Then, the above-described members can be manufactured by thermocompression molding as an integral molded body by a molding method such as a lamination method. At this time, the front sealing material 3 made of a single-layer sheet and the glass substrate are laminated, or the adhesion reinforcing layer of the front sealing material 3 made of a multilayer sheet is an example of the transparent front substrate 2. By laminating so as to face the glass substrate, the adhesion between the glass substrate and the sealing material can be improved.

  The solar cell module of the present invention thus obtained is characterized by excellent adhesion between a transparent substrate composed of glass or the like and a sealing material. That is, since the solar cell module of the present invention improves the adhesion strength between the transparent substrate made of glass or the like and the sealing material, it is exposed to harsh environments such as strong ultraviolet rays, heat rays, and wind and rain. Even in this case, it has extremely high durability over a long period of time.

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>
[Example]
A composition containing 85 parts by mass of the following polyethylene resin (A1), 15 parts by mass of the silane-modified polyethylene resin (B2), and 0.6 parts by mass of a crosslinking agent is mixed and melted with the composition shown in Table 1. And it formed into a film so that it might become thickness of 400 micrometers by the normal method T-die method, and obtained the single layer sealing material sheet | seat for solar cell modules. The film forming temperature was a resin temperature of 95 ° C. As a result of the GPC measurement, the number average molecular weight derived from the polyethylene resin (A1) in the encapsulant sheet was 55,000, and the number average molecular weight derived from the polyethylene resin (B2) was 115,000. .
Polyethylene resin (A1), indicated as LLDPE1 in Table 1, a copolymer of ethylene and 1-hexene, with a density of 0.880 g / cm ³ and a melt mass flow rate (MFR) at 190 ° C. of 30 g / 10 min Metallocene linear low density polyethylene. Number average molecular weight 55,000 in terms of polystyrene.
Polyethylene resin (B1): a copolymer of ethylene and 1-hexene, a density of 0.880 g / cm ³ , and a melt mass flow rate (MFR) at 190 ° C. of 3.0 g / 10 min. Chain low density polyethylene. Number average molecular weight 100,000 in terms of polystyrene.
Silane-modified polyethylene resin (B2), labeled as Si resin in Table 1, with respect to 98 parts by mass of the polyethylene resin (B1) base resin, 2 parts by mass of vinyltrimethoxysilane, and a radical generator (reaction catalyst) A silane-modified polyethylene resin having a density of 0.884 g / cm ³ and an MFR at 190 ° C. of 1.5 g / 10 min, mixed with 0.1 part by weight of dicumyl peroxide, melted and kneaded at 200 ° C. Got.
Cross-linking agent (TBEC): t-butylperoxy-2-ethylhexyl carbonate (manufactured by Arkema Yoshitomi, trade name Luperox TBEC)
Crosslinking aid (TAIC): triallyl isocyanurate (manufactured by Statomer, trade name SR533)
UV absorber (labeled UV in Table 1): Chemipro Kasei Co., Ltd., trade name KEMISORB12
Weather resistance stabilizer: Ciba Japan Co., Ltd., trade name Tinuvin 770
Silane coupling agent 1 (labeled SC in Table 1): 3-methacryloxypropyltriethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd., trade name KBM503

[Comparative Example 1]
Without using the silane-modified polyethylene resin (B2), 100 parts by mass of the polyethylene resin (A1) and 0.6 parts by mass of the cross-linking agent were mixed in the composition of Table 1 and melted. A single layer sealing material for a solar cell module was obtained by forming a film to a thickness of 400 μm by a conventional T-die method. The film forming temperature was a resin temperature of 95 ° C.

[Comparative Example 2]
The following EVA resin composition containing a crosslinking agent using EVA having an MFR at 190 ° C. of 30 g / 10 min was formed into a film having a thickness of 400 μm by a conventional T-die method. A layer sealant was obtained. The film forming temperature was 95 ° C. Comparative Example 2 is a conventionally known thermosetting type that is crosslinked during vacuum lamination.
EVA 100 parts by mass: vinyl acetate content 33%, manufactured by Mitsui DuPont Polychemical, trade name EVAFLEX / EV150R grade, MFR 30 g / 10 min. Crosslinker (TBEC) 0.75 parts by mass: t-butylperoxy-2-ethylhexyl carbonate (Arkema) (Product name: Lupelocks TBEC, manufactured by Yoshitomi Corporation)
Cross-linking aid (TAIC) 0.5 parts by mass: triallyl isocyanurate (manufactured by Sartomer, trade name SR533)
Silane coupling agent 0.5 parts by mass: manufactured by Shin-Etsu Chemical Co., Ltd., trade name KBM503
0.3 parts by mass of UV absorber: manufactured by Chemipro Kasei Co., Ltd., trade name KEMISORB12)
Antioxidant 0.01 part by mass: BASF Corporation, trade name Irganox 1076
Hindered amine light stabilizer (HALS) 0.1 part by mass: manufactured by BASF, Tinuvin 770

<Evaluation Example 1>
5 cm × 5 cm of the sealing material sheets of Examples and Comparative Examples are sandwiched between glass substrates, heated to 150 ° C., and after evacuation 5 minutes, pressurization (0 kPa → 100 kPa) 1.5 minutes, pressure holding 100 kPa Holding for 7 minutes, the magnification (%) before and after vacuum lamination was evaluated.

  As a result, compared with 160% in the example, the comparative example 1 is 200% and the comparative example 2 of EVA is 155%. In the example, the vacuum heating laminate is compared with the comparative example 1 to the same degree as EVA. It can be understood that the flow is sometimes suppressed.

<Evaluation Example 2>
About the sealing material sheet | seat of an Example and a comparative example, said sealing material for uncrosslinked solar cell modules is made to adhere | attach on a glass substrate (white board float semi-tempered glass JPT3.2 75mm * 50mm * 3.2mm). The vacuum heating laminator process was performed. Thereafter, the sealing material adhered on the glass substrate was cut to a width of 15 mm, and a vertical peeling (50 mm / min) test was conducted with a peeling tester (Tensilon universal testing machine RTF-1150-H). The glass adhesion strength after a month was measured (N / 15 mm). The results are shown in Table 2. From Table 2, it can be understood that the decrease in the glass adhesion strength is small in the examples.

DESCRIPTION OF SYMBOLS 1 Solar cell module 2 Transparent front substrate 3 Front sealing material 4 Solar cell element 5 Back surface sealing material 6 Back surface protection sheet

Claims (7)

A polyethylene resin (A) having an MFR at 190 ° C. and a load of 2.16 kg measured in accordance with JIS K7210 of 25 g / 10 min to 40 g / 10 min;
A polyethylene resin (B) having an MFR of 190 g and a load of 2.16 kg measured in accordance with JIS K7210 and having a load of 2.16 kg of 1 g / 10 min to 3 g / 10 min;
A crosslinking agent (C),
The sealing material composition for solar cell modules whose mass ratio of the said polyethylene-type resin (A) and the said polyethylene-type resin (B) is 90:10 to 75:25. The encapsulant composition according to claim 1, wherein each of the polyethylene resin (A) and the polyethylene resin (B) is a linear low density polyethylene having a density of 0.900 g / cm ³ or less.   The encapsulant composition according to claim 1 or 2, wherein the polyethylene resin (A) and / or the polyethylene resin (B) is a silane-modified polyethylene resin obtained by graft polymerization of an ethylenically unsaturated silane compound.   The encapsulant composition according to any one of claims 1 to 3, wherein the polyethylene resin (B) is a silane-modified polyethylene resin obtained by graft polymerization of an ethylenically unsaturated silane compound.   The encapsulant composition according to claim 3 or 4, wherein a graft amount of the ethylenically unsaturated silane compound with respect to 100 parts by mass of the resin component is 0.001 to 15 parts by mass.   The sealing material sheet for solar cell modules formed by melt-molding the sealing material composition in any one of Claim 1 to 5. A polyethylene resin (A) having a density of 0.900 g / cm ³ or less and an MFR at 190 ° C. and a load of 2.16 kg measured in accordance with JIS K7210 of 25 g / 10 min to 40 g / 10 min;
A polyethylene resin (B) having a density of 0.900 g / cm ³ or less and an MFR measured at 190 ° C. and a load of 2.16 kg measured in accordance with JIS K7210 is 1 g / 10 min or more and 3 g / 10 min or less. And
The mass ratio of the polyethylene resin (A) and the polyethylene resin (B) is 90:10 to 75:25,
The number average molecular weight derived from the polyethylene resin (A) is 50,000 or more and 70,000 or less,
The sealing material sheet for solar cell modules whose number average molecular weight derived from the said polyethylene-type resin (B) is 8.5-130,000.

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