JP2013075944A - Ethylene-vinyl acetate copolymer composition, glass adhesive sheet, and solar cell module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ethylene-vinyl acetate copolymer composition in which the crosslinking characteristic can be performed according to a first design even if being kept for a long period of time, and the adhesion decrease to a glass plate is prevented.SOLUTION: The ethylene-vinyl acetate copolymer composition includes: an ethylene-vinyl acetate copolymer; a silane coupling agent oligomer; and a crosslinking agent consisting of an organic peroxide, wherein the silane coupling agent oligomer is obtained by that 3-methacryloxy propyl trimethoxysilane is performed by hydrolysis and condensation so that the following (a) and (b) are fulfilled. (a) In an infrared absorption spectrum, the ratio of absorption of a methoxy group to absorption of a vinyl group is at most 0.05. (b) In an infrared absorption spectrum, the ratio of absorption of a silanol group that originates in the silane coupling agent oligomer to absorption of a vinyl group is at least 0.4.

Description

  The present invention relates to an ethylene-vinyl acetate copolymer composition containing an ethylene-vinyl acetate copolymer. Moreover, it is related with the glass adhesive sheet which has adhesiveness to a glass plate. Moreover, it is related with the solar cell module using a glass adhesive sheet.

In recent years, with the growing interest in environmental issues, the spread of solar power generation has been rapidly expanding. Usually, in solar power generation, a plurality of solar cells that are power generation elements are electrically connected to each other and are sandwiched between a pair of sheet-like sealing materials, and these are further attached to a glass plate and a back sheet as a protective material. A sandwiched solar cell module is used. As a sealing material for solar cells, a material mainly composed of an ethylene-vinyl acetate copolymer is widely used (see, for example, Patent Document 1).
As described in Patent Document 1, normally, a crosslinking agent made of an organic peroxide is added to the sealing material, and an EVA crosslinking reaction is caused by heating during the sealing process, thereby sealing the sealing material. The durability of the stopper is improved.
In addition, a silane coupling agent such as 3-methacryloxypropyltrimethoxysilane is also added to the sealing material, thereby improving the adhesion with a glass plate or a solar battery cell.

JP 2000-174296 A

However, when the sealing material described in Patent Document 1 is stored for a long period of time, the cross-linking characteristics (cross-linking speed) during the sealing process may not be as originally designed, and the adhesiveness may be lowered. Therefore, the obtained solar cell module may vary in durability and power generation performance.
Further, a sheet similar to the encapsulant is used for the interlayer film of the laminated glass. However, like the encapsulant, the adhesiveness is lowered after long-term storage, and the durability may vary.
An object of the present invention is to provide an ethylene-vinyl acetate copolymer composition and a glass adhesive sheet in which cross-linking characteristics can be maintained as originally designed even when stored for a long period of time, and a decrease in adhesion to a glass plate is prevented. To do. It is another object of the present invention to provide a solar cell module having high durability and power generation performance.

  The present inventors investigated the cause of the deterioration of the adhesive properties when the sealing material was stored for a long period of time and the cross-linking characteristics did not become as originally designed. As a result, it has been found that when the sealing material is stored for a long period of time, the silane coupling agent is hydrolyzed and further causes a condensation reaction to form a polymer having a three-dimensional structure. Since the polymer having the three-dimensional structure has a structure that causes steric hindrance, the radical derived from the crosslinking agent hardly reacts with the vinyl group of the silane coupling agent. As a result, the amount of radicals that react with EVA is greater than before the silane coupling agent condenses, so that the EVA crosslinking characteristics do not become as originally designed. Further, it was found that when the silane coupling agent is condensed, the silanol group exhibiting adhesiveness is reduced, so that the adhesiveness is lowered. As a result of further studies by the present inventors based on these findings, it was found that the above-mentioned problems can be solved by condensing the silane coupling agent to some extent in advance, and the following ethylene-vinyl acetate copolymer composition was found. Invented a glass adhesive sheet and a solar cell module.

[1] An ethylene-vinyl acetate copolymer, 0.05 to 10 parts by mass of a silane coupling agent oligomer with respect to 100 parts by mass of the ethylene-vinyl acetate copolymer, and a crosslinking agent comprising an organic peroxide And the silane coupling agent oligomer is obtained by hydrolyzing and condensing 3-methacryloxypropyltrimethoxysilane so as to satisfy the following (a) and (b): -Vinyl acetate copolymer composition.
(A) In the infrared absorption spectrum, the ratio of methoxy group absorption to vinyl group absorption is 0.05 or less.
(B) In the infrared absorption spectrum, the ratio of silanol group absorption due to the silane coupling agent oligomer to vinyl group absorption is 0.4 or more.
[2] A glass adhesive sheet comprising the ethylene-vinyl acetate copolymer composition according to [1].
[3] A solar battery cell and a pair of solar battery sealing materials sandwiching the solar battery cell, wherein the solar battery sealing material is the glass adhesive sheet according to [2]. A solar cell module.

The ethylene-vinyl acetate copolymer composition and glass adhesive sheet of the present invention can have a crosslinking property as originally designed even when stored for a long period of time, and a decrease in adhesion to a glass plate is prevented.
The solar cell module of the present invention has high durability and power generation performance.

It is sectional drawing which shows one embodiment of the solar cell module of this invention.

<Ethylene-vinyl acetate copolymer composition>
The ethylene-vinyl acetate copolymer composition of the present invention contains an ethylene-vinyl acetate copolymer (hereinafter referred to as “EVA”), a silane coupling agent oligomer, and an organic peroxide.

(EVA)
EVA has a vinyl acetate unit ratio of preferably 10 to 40% by mass, and more preferably 15 to 35% by mass. If the ratio of vinyl acetate units in EVA is not less than the lower limit, the transparency and adhesiveness of the sheet obtained from the composition can be increased, and if it is not more than the upper limit, durability can be further increased.
The mass average molecular weight of EVA is preferably 10,000 to 300,000, and more preferably 30,000 to 100,000. If the EVA weight average molecular weight is not less than the lower limit, the mechanical properties of the sheet obtained from the composition can be improved, and if it is not more than the upper limit, the workability can be improved.

(Silane coupling agent oligomer)
The silane coupling agent oligomer is obtained by hydrolyzing and condensing 3-methacryloxypropyltrimethoxysilane so as to satisfy the following (a) and (b).

(A) in the infrared absorption spectrum, the absorption of the vinyl group (wave number: 1260 cm ^-1) absorption of methoxy group to the (wave number: 2842cm ^-1) ratio of is 0.05 or less, preferably 0.03 or less, More preferably, it is 0.01 or less, and most preferably 0.
When 3-methacryloxypropyltrimethoxysilane is hydrolyzed, the methoxysilane group becomes a silanol group. Therefore, the ratio of methoxy group absorption to vinyl group absorption is reduced. That the ratio of methoxy group absorption to vinyl group absorption is not more than the above upper limit value means that hydrolysis is almost complete, that is, methoxysilane group is almost silanol group. If the ratio of methoxy group absorption to vinyl group absorption exceeds the above upper limit, hydrolysis is not completed, so the cross-linking characteristics are as originally designed when stored for a long time. In other words, the adhesion to the glass plate may be reduced.

(B) in the infrared absorption spectrum, the absorption of the vinyl group (wave number: 1260 cm ^-1) absorption of silanol group due to the silane coupling agent oligomer for (wavenumber: 980 cm ^-1) is the ratio of 0.4 or more, More preferably, it is 0.5 or more. In addition, the ratio of silanol group absorption due to the silane coupling agent oligomer to vinyl group absorption is preferably 1.0 or less, and more preferably 0.8 or less.
After 3-methacryloxypropyltrimethoxysilane is hydrolyzed, silanol groups are dehydrated and condensed to polymerize. Therefore, the ratio of silanol group absorption due to the silane coupling agent oligomer to vinyl group absorption increases. The ratio of the silanol group absorption resulting from the silane coupling agent oligomer to the vinyl group absorption being equal to or greater than the lower limit means that the condensation has progressed to some extent. When the ratio of silanol group absorption due to the silane coupling agent oligomer to vinyl group absorption is less than the above lower limit value, the cross-linking characteristics will not be as originally designed when stored for a long time. , Adhesiveness to the glass plate may be reduced.
The vinyl group absorption, the methoxy group absorption and the silanol group absorption were prepared by preparing a measurement sample in which an oligomer was coated on a KBr disk, and using an FT-IR measurement apparatus to transmit infrared rays of 400 to 4000 cm ⁻¹ by a transmission method. Measured and identified / quantified by each absorption peak.

Examples of the hydrolysis and condensation methods include a method of adding water and an organic solvent to 3-methacryloxypropyltrimethoxysilane and stirring them. At that time, the progress of the reaction can be adjusted by the reaction time, pH or reaction temperature. In particular, pH is an important condition for adjusting the reaction rate of the hydrolysis reaction and the condensation reaction. That is, since the minimum value of the reaction rate of the condensation reaction appears when the pH is weakly acidic, preferably in the range of 3.5 to 4.0, first, the hydrolysis reaction is sufficiently performed under the weakly acidic conditions, or the hydrolysis is performed. After the reaction is completed, a desired reaction product can be obtained by gradually advancing the condensation reaction. When the pH is on the alkali side (7 or more), the hydrolysis reaction rate decreases, while the condensation reaction increases, making it difficult to obtain the desired reactant. Therefore, the pH is preferably 3.5 to 4.0.
The condensation reaction and the hydrolysis reaction proceed as the reaction temperature is increased and the reaction time is lengthened. However, in order for the hydrolysis to proceed sufficiently or completely and to achieve a sufficient degree of condensation, infrared rays are used. It is preferable to adjust the conditions (reaction temperature, reaction time, etc.) while confirming the degree of progress with a spectrometer or the like.
The pH may be adjusted by adding an acid (for example, acetic acid or the like) or an alkali.

  The content of the silane coupling agent oligomer is 0.05 to 10 parts by mass, preferably 0.1 to 5 parts by mass, and more preferably 0.1 to 2.0 parts by mass. If the content of the silane coupling agent oligomer is not less than the above lower limit value, the adhesiveness to glass can be further increased. Can be crosslinked.

(Crosslinking agent)
The crosslinking agent is an organic peroxide for crosslinking EVA. Examples of the organic peroxide include peroxydicarbonates, peroxyketals, dialkyl peroxides, peroxyesters, hydroperoxides, and the like.
0.01-5 mass parts is preferable with respect to 100 mass parts of EVA, and, as for the compounding quantity of a crosslinking agent, 0.05-2 mass parts is more preferable. If the blending amount of the cross-linking agent is equal to or more than the lower limit, EVA can be sufficiently cross-linked, but even if blended in excess of 5% by mass, the degree of cross-linking will reach its peak and the amount of undecomposed residue will increase. However, this is inappropriate because it causes a decrease in durability (weather resistance), discoloration, and the like.

(Additive)
The ethylene-vinyl acetate copolymer composition may contain additives such as an ultraviolet absorber, a light stabilizer, an antioxidant, and a crosslinking aid.

Examples of the ultraviolet absorber include benzophenone-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, and salicylic acid ester-based ultraviolet absorbers.
Examples of the light stabilizer include hindered amine light stabilizers.
Examples of the antioxidant include hindered phenol antioxidants and phosphite antioxidants.

The crosslinking aid is a compound having one or more (preferably two or more) polymerizable unsaturated groups (vinyl group, allyl group, (meth) acryloxy group, etc.). Examples of the compound include triallyl isocyanurate, triallyl cyanurate, and trimethylolpropane trimethacrylate.
0-5 mass parts is preferable with respect to 100 mass parts of EVA, and, as for the compounding quantity of a crosslinking adjuvant, 0-2 mass parts is more preferable.

  In addition to the above additives, the ethylene-vinyl acetate copolymer composition may contain a discoloration inhibitor (such as a fatty acid metal salt), a pigment, a dye, a filler, and the like.

(Function and effect)
The silane coupling agent oligomer contained in the ethylene-vinyl acetate copolymer of the present invention has a large molecular size because hydrolysis of the silane coupling agent is completed and further condensed to some extent. Since oligomers having a large molecular size do not easily react with each other, it is possible to suppress a decrease in silanol groups when stored for a long period of time.
In addition, the oligomers hardly react with each other when stored for a long period of time, and the reaction with the crosslinking agent does not easily occur. Therefore, the reaction amount between the vinyl of the oligomer and the crosslinking agent hardly changes before and after storage. As a result, the amount of the crosslinking agent that contributes to EVA crosslinking is almost the same as that before storage, so that the crosslinking characteristics can be as originally designed.

<Glass adhesive sheet>
The glass adhesive sheet of this invention consists of the said ethylene-vinyl acetate copolymer.
Examples of the method for producing the glass adhesive sheet include a method of forming the ethylene-vinyl acetate copolymer into a sheet. Examples of the sheet forming method include an extrusion molding method using a T die, a press molding method, and the like. Moreover, it can also be formed into a sheet by applying a solution of the ethylene-vinyl acetate copolymer composition to the release sheet and drying.

(Thickness)
The thickness of a glass adhesive sheet is suitably selected within the range of 0.05-1 mm according to the solar cell module and laminated glass to produce. When the thickness of the glass adhesive sheet is 0.05 mm or more, the solar battery cell can be sufficiently sealed when used as a sealing material, and when used as an interlayer film for laminated glass, the glasses are sufficiently bonded together. Can be glued. On the other hand, if the thickness is 1 mm or less, the solar battery cell and the laminated glass can be thinned.

(Function and effect)
Since the glass adhesive sheet contains a silane coupling agent oligomer condensed to some extent, even when stored for a long period of time, the amount of the crosslinking agent that contributes to the crosslinking of EVA is almost the same as the state before storage, and the crosslinking characteristics are It can be done as originally designed. Moreover, even if it is stored for a long period of time, the amount of silanol groups contributing to the adhesiveness hardly changes, so that the adhesiveness to the glass plate is prevented from being lowered.
Such a glass adhesive sheet is suitably used as a sealing material for solar cells or an intermediate film for laminated glass.

<Solar cell module>
Next, an embodiment of a solar cell module using the glass adhesive sheet will be described.
In FIG. 1, sectional drawing of the solar cell module of this embodiment example is shown. The solar cell module 10 of the present embodiment includes a plurality of solar cells 11, 11,..., A pair of solar cell sealing materials 12, 12, a glass plate 13, and a back sheet 14. The solar battery cell 11 is sandwiched and fixed between a pair of solar battery sealing materials 12 and 12. Moreover, the sealing materials 12 and 12 are arrange | positioned between the glass plate 13 and the back sheet | seat 14, and the said glass adhesive sheet is used.

(Solar cell)
Examples of the solar battery cell 11 include a pn junction solar battery element having a structure in which a p-type semiconductor and an n-type semiconductor are joined. Examples of the pn junction type solar cell element include silicon (single crystal silicon, polycrystalline silicon, amorphous silicon, etc.), compound (GaAs, CIS, CdTe-CdS) and the like.
In the present embodiment example, the plurality of solar cells 11 are electrically connected in series via a tab string 15 having a conductive wire and a solder joint.

(Glass plate)
The glass plate 13 functions as a protective material for the solar battery cells 11 and the like. As the glass plate 13, a template glass having an uneven surface is preferable from the viewpoint of light transmittance. As the material of the template glass, white plate glass (high transmission glass) with less iron content is preferable.

(Back sheet)
Examples of the material of the back sheet 14 include polyvinyl fluoride, polyester (polyethylene terephthalate, etc.), polyolefin (polyethylene, etc.), glass, metal (aluminum, etc.) and the like. The backsheet 24 may be a single layer or a multilayer.

(Method for manufacturing solar cell module)
As a method for manufacturing a solar cell module, a plurality of solar cells 11, 11... Electrically connected using a tab string 15 are sandwiched between a pair of sealing materials 12, 12, and further the sealing materials 12, 12. Is sandwiched between the glass plate 13 and the back sheet 14 and then heated to bond the sealing materials 12 and 12, the sealing material 12 and the glass plate 13, and the sealing material 12 and the back sheet 14. It is done.
Heating in the above production method is preferably performed under conditions (temperature, time) under which the cross-linking agent is sufficiently decomposed because productivity increases. Moreover, if it heats on the conditions which a crosslinking agent fully decomposes | disassembles, EVA contained in the sealing material 12 can fully be bridge | crosslinked and the durability of the sealing material 11 can be improved more.

(Function and effect)
The solar cell module of the present invention using the above glass adhesive sheet as a sealing material has a sufficiently cross-linked glass adhesive sheet and sufficient adhesion between the glass adhesive sheet and the glass plate. high. Therefore, the solar cell module has high durability and power generation performance.

(Production Example 1)
50 g of 3-methacryloxypropyltrimethoxysilane (KBM-503 manufactured by Shin-Etsu Chemical Co., Ltd.) and acetic acid added to 20 g of ion-exchanged water were mixed with an acetic acid aqueous solution of pH 3.7 and 5 g of ethanol at 25 ° C. The mixture was stirred for 24 hours to obtain an oligomer of 3-methacryloxypropyltrimethoxysilane (OMPTMS (1)).

(Production Example 2)
A solution of acetic acid having a pH of 3.7 obtained by adding acetic acid to 50 g of 3-methacryloxypropyltrimethoxysilane and 20 g of ion-exchanged water was mixed with 5 g of ethanol, and the mixture was stirred at 40 ° C. for 24 hours to give 3-methacryloxy. An oligomer of propyltrimethoxysilane (OMPTMS (2)) was obtained.

(Production Example 3)
To 10 g of 3-methacryloxypropyltrimethoxysilane, 4 g of an acetic acid aqueous solution having a pH of 3.7 obtained by adding acetic acid to ion-exchanged water was mixed, and stirred at 25 ° C. for 15 minutes to give 3-methacryloxypropyltrimethoxy. An oligomer of silane (OMPTMS (3)) was obtained.

(Production Example 4)
44 g of 3-methacryloxypropyltrimethoxysilane, 7.8 g of ion-exchanged water, 65.7 g of acetone and 1.4 g of di-n-butylamine were mixed and stirred at 25 ° C. for 48 hours to give 3-methacryloxypropyl. An oligomer of trimethoxysilane (OMPTMS (4)) was obtained.

For the oligomers obtained in Production Examples 1 to 4 and 3-methacryloxypropyltrimethoxysilane (MPTMS), the infrared absorption spectrum was measured using an infrared absorption measurement apparatus (Nicolet 380 manufactured by Thermo Electron). From the obtained spectra, absorption of vinyl group (wavelength: 1260 cm ^-1): was determined the ratio of the absorption of the methoxy group to the (2842Cm ^-1 wavenumber). Further, absorption of vinyl group (wave number: 1260 cm ^-1) absorption of silanol group due to the oligomer for (wavenumber: 980 cm ^-1) was determined ratio of. The results are shown in Table 1.
From these results, OMPTMS (1) and OMPTMS (2) are hydrolyzed and have undergone moderate condensation.
OMPTMS (3) has not been completely hydrolyzed.
OMPTMS (4) is one in which hydrolysis is complete and condensation is almost complete.

Example 1
SEETEC EVA VE700 manufactured by ethylene-vinyl acetate copolymer (Lotte Daesan Petrochemical), vinyl acetate unit: 30% by mass, MFR (190 ° C.): 15 g / min), 100 parts by mass, cross-linking agent Yaku Akzo Kayahexa AD, dialkyl peroxide) 0.5 parts by mass, Cross-linking aid (Nippon Kasei Co., Ltd.) 0.5 parts by mass, UV absorber (BASF Japan TINUVIN P) 0.5 parts by mass Then, 0.5 parts by mass of a light stabilizer (TINUVIN114 manufactured by BASF Japan Ltd.) and 0.5 parts by mass of OMPTMS (1) obtained in Production Example 1 were mixed to obtain an ethylene-vinyl acetate copolymer composition. Subsequently, the obtained composition was press-molded to obtain a glass adhesive sheet having a thickness of 500 μm used as a solar cell sealing material.
Next, a plurality of polycrystalline silicon solar cells electrically connected in series are sandwiched between the two sheets obtained as described above, and these are sandwiched between a glass plate and a back sheet made of polyvinyl fluoride and polyester. To obtain a laminate. This laminate was put into a resin bag, the inside of the bag was evacuated, and heated to 150 ° C. for 30 minutes in a heating furnace to obtain a solar cell module.

(Example 2)
Glass bonding was performed in the same manner as in Example 1 except that 0.1 part by mass of OMPTMS (2) was blended in place of 0.5 part by mass of OMPTMS (1) to obtain an ethylene-vinyl acetate copolymer composition. Sex sheet was obtained. Moreover, the solar cell module was obtained like Example 1 using the glass adhesive sheet.

(Example 3)
Glass bonding was carried out in the same manner as in Example 1 except that 0.5 parts by mass of OMPTMS (1) was mixed with 0.5 parts by mass of OMPTMS (2) to obtain an ethylene-vinyl acetate copolymer composition. Sex sheet was obtained. Moreover, the solar cell module was obtained like Example 1 using the glass adhesive sheet.

Example 4
Glass bonding was carried out in the same manner as in Example 1 except that 2.0 parts by mass of OMPTMS (2) was blended instead of 0.5 parts by mass of OMPTMS (1) to obtain an ethylene-vinyl acetate copolymer composition. Sex sheet was obtained. Moreover, the solar cell module was obtained like Example 1 using the glass adhesive sheet.

(Comparative Example 1)
OMPTMS (1) In the same manner as in Example 1 except that 0.5 parts by mass of 3-methacryloxypropyltrimethoxysilane was blended to obtain an ethylene-vinyl acetate copolymer composition instead of 0.5 parts by mass. Thus, a glass adhesive sheet was obtained. Moreover, the solar cell module was obtained like Example 1 using the glass adhesive sheet.

(Comparative Example 2)
Glass bonding was carried out in the same manner as in Example 1 except that 0.5 parts by mass of OMPTMS (1) was mixed with 0.5 parts by mass of OMPTMS (3) to obtain an ethylene-vinyl acetate copolymer composition. Sex sheet was obtained. Moreover, the solar cell module was obtained like Example 1 using the glass adhesive sheet.

(Comparative Example 3)
Glass bonding was carried out in the same manner as in Example 1 except that 0.5 parts by mass of OMPTMS (1) was mixed with 0.5 parts by mass of OMPTMS (4) to obtain an ethylene-vinyl acetate copolymer composition. Sex sheet was obtained. Moreover, the solar cell module was obtained like Example 1 using the glass adhesive sheet.

(Comparative Example 4)
Glass bonding was performed in the same manner as in Example 1 except that 1.0 part by mass of OMPTMS (4) was blended instead of 0.5 part by mass of OMPTMS (1) to obtain an ethylene-vinyl acetate copolymer composition. Sex sheet was obtained. Moreover, the solar cell module was obtained like Example 1 using the glass adhesive sheet.

[Evaluation]
-Change in crosslinking property The obtained glass adhesive sheet was left in an environment of a temperature of 30 ° C and a relative humidity of 80% RH for 3 months, and the change in the crosslinking property every month was examined. The evaluation results are shown in Table 2. The cross-linking characteristics were obtained by using a JSR Trading Co., Ltd., Curalastometer Model 7 under a measurement condition at 150 ° C. for 30 minutes. From the curve, the time until the torque reached a constant value (0.05 N · cm) was measured. The smaller the change in the time, the less the change over time and the better the cross-linking properties as originally designed.
-Adhesiveness with glass plate The tensile strength of the adhesive strength between the glass adhesive sheet and the glass plate in the obtained solar cell module was measured in a 23 ° C environment using a tensile testing machine (AG-5000A manufactured by Shimadzu Corporation). A 180 ° peel test was performed at 200 mm / min, and the peel strength was measured. The peel strength was defined as the adhesive strength.
The adhesive strength was also measured for a glass adhesive sheet left for 3 months in an environment of 30 ° C. and a glass adhesive sheet left for 1000 hours in an environment of 85 ° C. and 85% relative humidity.
Table 2 shows the measurement results of the obtained adhesive strength.

In Examples 1 to 4 using an oligomer obtained by appropriately condensing a silane coupling agent, the crosslinking property of the glass adhesive sheet hardly changed even when left for 3 months. Moreover, the adhesiveness with respect to a glass plate was sufficient.
In Comparative Example 1 using the silane coupling agent as it was, the cross-linking characteristics of the glass adhesive sheet were significantly changed after being left for 3 months, and the adhesiveness was lowered.
In Comparative Example 2 using the oligomer in which the hydrolysis of the silane coupling agent was not completed, the cross-linking characteristics of the glass adhesive sheet changed significantly after standing for 3 months, and the adhesiveness was lowered.
In Comparative Examples 3 and 4 using oligomers in which the hydrolysis of the silane coupling agent was completed but the condensation was hardly advanced, the adhesion to the glass plate was low from the beginning. Moreover, it turned out that adhesiveness is not improved even if it increases an oligomer compounding quantity from the comparison with Comparative Examples 3 and 4.

DESCRIPTION OF SYMBOLS 10 Solar cell module 11 Solar cell 12 Sealing material 13 Glass plate 14 Back sheet 15 Tab string

Claims (3)

It contains an ethylene-vinyl acetate copolymer, 0.05 to 10 parts by mass of a silane coupling agent oligomer with respect to 100 parts by mass of the ethylene-vinyl acetate copolymer, and a crosslinking agent made of an organic peroxide. ,
The silane coupling agent oligomer is obtained by hydrolyzing and condensing 3-methacryloxypropyltrimethoxysilane so as to satisfy the following (a) and (b). Polymer composition.
(A) In the infrared absorption spectrum, the ratio of methoxy group absorption to vinyl group absorption is 0.05 or less.
(B) In the infrared absorption spectrum, the ratio of silanol group absorption due to the silane coupling agent oligomer to vinyl group absorption is 0.4 or more.   A glass adhesive sheet comprising the ethylene-vinyl acetate copolymer composition according to claim 1.   A solar cell comprising a solar cell and a pair of solar cell encapsulants sandwiching the solar cell, wherein the solar cell encapsulant is the glass adhesive sheet according to claim 2. Battery module.

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