JP2011077172A - Sealing material sheet and solar battery module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sealing material sheet featuring the improved steam barrier property of an EVA layer, which is the constituent material of the sheet. <P>SOLUTION: Sealing material sheets 2-1 are so arranged as to sandwich a photoelectric conversion cell 3 disposed between a front surface protective member 1 and a rear surface protective member 4 and are used as a member of a solar battery to be integrated by heat-pressing a laminate composed of all the members (1 to 4) for integration. The sealing material sheet 2-1 is composed of two layers including an EVA layer 2-1a and an ionomer layer 2-1b of ethylene and unsaturated carboxylic acid copolymer. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a sealing material sheet used for sealing a solar battery cell in a manufacturing process of a solar battery module and the like, and a solar battery module using the sealing material sheet.

  In recent years, solar cells have attracted attention as a technique for generating electric energy in a clean state using sunlight.

  As shown in the cross-sectional view of FIG. 3, a general solar battery module has a laminated structure in which a surface protection member 11, a sealing material 12, a solar battery cell 13, and a back surface protection member 14 are arranged in this order. The solar battery cell 13 disposed between the member 11 and the back surface protection member 14 is completely sealed with the sealing material 12.

  As a manufacturing procedure of such a solar cell module, as shown in FIG. 4, a surface protection member 11, a sealing material sheet 12-1, a plurality of solar cells 13 arranged at predetermined intervals, a sealing material sheet 12-1, after the laminated structure laminated | stacked in order of the back surface protection member 14 was heated and deaerated in a vacuum, it heated again, applying a 1 atmosphere load in a vacuum, and the sealing material sheet 12 It is manufactured by cross-linking and curing the resin which is -1 and integrating them.

  By the way, EVA (ethylene-vinyl acetate copolymer) is often used as the main resin for the sealing material sheet 12-1. For the purpose of enhancing durability, additives such as a crosslinking agent, a crosslinking assistant, a silane coupling agent, a light stabilizer, and an ultraviolet absorber are often added to the EVA resin at a certain ratio.

  As a manufacturing method of the sealing material sheet 12-1, a molten resin is extruded by a T-die method in which a molten resin is extruded from a die having a linear slit and rapidly cooled and solidified in a cooling roll or a water tank, or by rotating several rolls arranged. The encapsulant sheet 12-1 having a thickness of about 500 μm is formed into a film by using a calendering method or the like that imparts shear deformation and stretches. Moreover, the embossing which gives an unevenness | corrugation to the sealing material sheet surface in the stage of these film forming processes may be given (patent document 1).

Japanese Patent No. 3323560

  By the way, in the conventional general solar cell module including the technique described in Patent Document 1, a single-layered sealing material sheet 12-1 is used, and the most main composition of the sealing material sheet 12-1. As an EVA type.

  However, since EVA has a water vapor transmission rate of about 5.1 g · mil / 100 in 2 · day, due to adhesion inhibition by water vapor, the layer of the encapsulant sheet 12-1 in contact with the solar cells 13 is lifted. May end up.

  Here, MVTR (Moisture Vapor Transmission Rate) is given in g · mil / 100 in 2 · day, measured at 20 ° C., and conforms to US Material Test Standard No. ASTM F1249-99.

  As a result, when the water vapor transmission rate is high, moisture in the atmosphere permeates, adversely affects the adhesion of EVA in contact with the solar battery cell 13, and there is a problem that it is difficult to ensure uniform quality of the solar battery module.

  The present invention solves the above-described problems of the prior art, and an object thereof is to provide a sealing material sheet and a solar cell module that can improve the water vapor barrier property of the EVA layer as a main constituent material. To do.

  In order to solve the above-described problem, the invention corresponding to claim 1 is provided so as to sandwich the photoelectric conversion cell in order to seal the photoelectric conversion cell disposed between the front surface protection member and the back surface protection member. In an encapsulant sheet used as a solar cell member obtained by laminating all the members to form a laminate and thermocompression bonding the laminate, an ionomer of an EVA layer and an ethylene / unsaturated carboxylic acid copolymer It is the sealing material sheet comprised by 2 layers which consist of a layer.

  The invention corresponding to claim 2 is an ethylene / unsaturated carboxylic acid for improving the water vapor barrier property of the EVA layer in contact with the photoelectric conversion cell on the side surface opposite to the sealing side surface of the EVA layer in contact with the photoelectric conversion cell. It is the sealing material sheet which laminated | stacked the ionomer layer of the copolymer and made it 2 layer structure.

  According to a third aspect of the present invention, the ionomer layer of the ethylene / unsaturated carboxylic acid copolymer is formed to have a thickness not less than 10 μm and not exceeding the thickness of the EVA layer. It is.

  Furthermore, the invention corresponding to Claim 4 is a structure which implement | achieves a solar cell module by sealing a photovoltaic cell using the sealing agent sheet | seat mentioned above.

  According to the present invention, a two-layer configuration of an EVA layer and an ionomer layer of an ethylene / unsaturated carboxylic acid copolymer can improve the water vapor barrier property of the EVA layer in contact with the photoelectric conversion cell. A material sheet and a solar cell module can be provided.

The figure which shows the arrangement structure of each member at the time of solar cell module manufacture at the time of using the sealing material sheet which concerns on this invention. The figure which shows the evaluation result of the float confirmation of the sealing material sheet which contact | connects the workability when the number of layers of a sealing material sheet, each layer thickness of EVA, and an ionomer is varied. Sectional drawing of the conventional solar cell module. The figure which shows the arrangement structure of each member at the time of the conventional solar cell module manufacture.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a member arrangement configuration diagram of a solar cell module to which a sealing material sheet according to the present invention is applied.

  This solar cell module includes a surface protective member (for example, white glass) 1, a sealing material sheet 2-1 according to the present invention, a plurality of photoelectric conversion cells (for example, solar cells) 3,..., And a sealing material according to the present invention. It is a laminated structure in which the sheet 2-1 and the back surface protection member (for example, vinyl fluoride polymer) 4 are arranged in this order.

  The encapsulant sheet 2-1 according to the present invention includes two constituent member layers 2-1a and 2-1b, and EVA (ethylene-vinyl acetate copolymer) is included in the main constituent member layer 2-1a. Used. The reason for using EVA is that the past use record is enormous and sufficiently reliable based on having high transparency and being inexpensive.

  As described above, an organic peroxide is added to the encapsulant sheet 2-1 as a crosslinking agent for initiating the EVA crosslinking reaction. Examples of organic peroxides include 1,1-di (t-butylperoxy) cyclohexane, 1,1-di (t-hexylperoxy) cyclohexane, n-butyl 4,4-di- (t-butylperoxy). ) Valerate, t-butylperoxy-3,5,5-trimethylhexanoate, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, t-butylcumyl peroxide, 2,2 -Di- (t-butylperoxy) butane etc. are mentioned.

  Moreover, you may add the additive for accelerating | stimulating a crosslinking reaction other than the said crosslinking agent to the sealing material sheet 2-1. Examples of the crosslinking reaction promoting additive include triallyl isocyanurate, diallyl phthalate, triallyl cyanurate, and the like.

  In addition, γ-methacryloxypropylsilane is added to the encapsulant sheet 2-1 as a silane coupling agent in order to improve the adhesion to the white plate glass or the vinyl fluoride polymer used as the protective members 1 and 4. . Examples of the silane coupling agent include trimethoxypropylsilane, trimethoxymethylsilane, vinyltrimethoxysilane, vinyltriethoxysilane, trichloropropylsilane, triethoxyphenylsilane, etc. And since it is cheap, γ-methacryloxypropyltrimethoxysilane is used in almost all cases.

  Furthermore, you may add a ultraviolet absorber and antioxidant to a sealing material sheet 2-1 from a viewpoint of light resistance or thermal stability. In addition, as an ultraviolet absorber used in order to improve light resistance, 2- (5-methyl-2-hydroxyphenyl) benzotriazole, 2- (3-t-butyl-5-methyl-2-hydroxyphenyl) -5-chlorobenzotriazole, 2- (4,6-diphenyl-1,3,5-triazin-2-yl) -5-[(hexyl) oxy] -phenol, 2,4-dihydroxybenzophenone, 2-hydroxy -4-n-octyloxybenzophenone and the like.

  Antioxidants used for improving thermal stability include 1,6-hexanediol-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], pentaerythrityl- Tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], tris (2,4-di-tert-butylphenyl) phosphite, 2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-t-butylanilino) -1,3,5-triazine and the like can be mentioned.

  As described above, the sealing material sheet 2-1 according to the present invention includes the two constituent member layers 2-1a and 2-1b. The two constituent member layers 2-1a and 2-1b are an ionomer layer of an ethylene / unsaturated carboxylic acid copolymer that becomes the subordinate constituent member layer 2-1b and an EVA layer that becomes the main constituent member layer 2-1a. Preferably there is. If this is a single-layer structure composed of only EVA, the water vapor barrier property is not sufficient, water vapor in the air permeates, adversely affects the adhesion, and causes the layer in contact with the photoelectric conversion cell 3 to float. In order to improve the water vapor barrier property, ethylene / unsaturation for improving the water vapor barrier property of the EVA layer in contact with the photoelectric conversion cell 3 on the surface portion (outer surface portion) opposite to the photoelectric conversion cell 3 of the EVA layer An ionomer layer of a carboxylic acid copolymer is overlaid.

  Regarding the unsaturated carboxylic acid content of the ethylene / unsaturated carboxylic acid copolymer ionomer, if the content is too low, the transmittance is lowered, and if it is too high, the melting point is lowered, so that the content is 5 to 25% by weight. Is preferred.

  Examples of the unsaturated carboxylic acid include acrylic acid, methacrylic acid, maleic acid, and maleic anhydride, and acrylic acid or methacrylic acid is preferable from the viewpoint of transmittance.

  As the metal species of the ethylene / unsaturated carboxylic acid copolymer ionomer, alkali metals such as lithium and sodium, polyvalent metals such as alkali metals, calcium, magnesium, zinc and aluminum can be used.

  Considering flexibility and the like, it is not a good idea to use an ionomer having a very high degree of neutralization. For example, it is preferable to use an ionomer having a degree of neutralization of 60% or less, particularly 30% or less.

  The ionomer is an ionomer of an ethylene / unsaturated carboxylic acid copolymer having an unsaturated carboxylic acid unit content of 5 to 25% by weight considering the balance of transparency, adhesiveness and heat resistance, and is neutralized. It is particularly preferable to use one having a degree of 1 to 30% and a melting point of 90 to 110 ° C.

  The EVA or ionomer has a melt flow rate (MFR) at 190 ° C. and a load of 2160 g (JIS K7210-1999, the same shall apply hereinafter) of 0.1 to 200 g / 10 minutes, particularly 1 to 100 g / 10 minutes. It is preferred to use. Here, MFR is an index indicating the fluidity of the resin. When using a material with a low MFR, there is an advantage that troubles due to the flow of the sealing material hardly occur even if a material with a slightly lower melting point is used. Deteriorate. On the other hand, if an MFR having an excessively high MFR is used, the module protrudes from the end when the module is produced and adheres to the laminate, and it takes time to remove the deposit, resulting in extremely low production efficiency.

  The thickness of the ethylene / unsaturated carboxylic acid copolymer ionomer layer is preferably 10 μm or more. When it is less than 10 μm, the effect of improving the water vapor barrier property is weak. The thickness of the ethylene / unsaturated carboxylic acid copolymer ionomer layer is preferably in a range not exceeding the thickness of the EVA layer. When the thickness of the ethylene / unsaturated carboxylic acid copolymer ionomer layer exceeds the thickness of the EVA layer, curling due to thermal shrinkage of the film during processing is remarkable, which causes a decrease in productivity.

  As an example of a method for producing the sealing material sheet 12-1, a resin obtained by mixing and heating and melting main materials and additives is formed into a film by a coextrusion method using a T-die having a linear slit. The sealing material sheet 12-1 is manufactured.

  Further, in order to prevent blocking, in the film forming process, the resin sheet in a heated and melted state is applied to a roll (made of metal or rubber) having a concavo-convex pattern on the surface, whereby one side of the sealing material sheet or The uneven pattern of the roll may be transferred to both surfaces, and the encapsulant sheet 12-1 may be embossed.

  Each Example and Comparative Example will be described with reference to FIG. FIG. 2 is a diagram showing the workability when the number of constituent member layers, the layer thickness of EVA and the ionomer are varied, and the evaluation results of confirmation of the floating of the sealing material sheet 12-1 with respect to the photoelectric conversion cell 3.

Example 1
In Example 1, first, an EVA resin having a vinyl acetate content of 30% by weight was used. Moreover, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane was used as a crosslinking agent (organic peroxide). Triallyl isocyanurate was used as a crosslinking aid. As the silane coupling agent, γ-methacryloxypropyltrimethoxysilane was used.

  On the other hand, as the resin of the ethylene / unsaturated carboxylic acid copolymer ionomer, the unsaturated carboxylic acid was acrylic acid, the content was 15% by weight, the metal species was zinc, and the neutralization degree was 20%.

  About the above compositions, the sheet | seat was shape | molded by coextrusion so that the film thickness of each layer might become the thickness of Example 1 of FIG. 2 using the extrusion molding machine. The film thickness of each layer was measured with an electronic micrometer (K351C manufactured by Anritsu).

  As a result, in Example 1, since it was set as two structural member layers, the float was not confirmed between the photoelectric conversion cell 3 and the sealing material sheet 2-1, not only processability. On the other hand, in the case of the single-layer configuration as in Comparative Examples 5 to 7, the photoelectric conversion cell 3 and the encapsulant sheet 12 are simply changed by changing the thickness of the EVA layer as indicated by “x”. It was confirmed that there was a float between -1.

  In (Example 2) to (Example 5) and (Comparative Example 1) to (Comparative Example 7), the number of constituent member layers described in each Example and each Comparative Example shown in FIG. A sheet was molded according to the same material composition and molding method as in No. 1.

  And about the sealing material sheet obtained by the Example shape | molded as mentioned above and a comparative example, "workability" (generation of the curl by the heat | fever change of the film at the time of a process) and "floating confirmation" (effect of water vapor | steam) And whether or not a floating portion was generated in a layer in contact with the photoelectric conversion cell due to a decrease in sealing performance. Details of the evaluation criteria are shown below.

"Processability"
The two sealing material sheets obtained in the examples and comparative examples, the surface protection member 1 and the back surface protection member 4 are overlapped as shown in FIG. 1 and cured at 150 ° C. for 10 minutes while being pressurized at 1 atm. Created a module. White glass (3 mm thickness) was used as the surface protection member 1, and vinyl fluoride polymer (38 μm thickness) was used as the back surface protection member 4.

  In the process of raising the temperature to 150 ° C., a sample having a two-layer structure causes curling due to the difference in the linear expansion coefficient of each layer. When a problem occurs due to a dimensional change due to curling in the module creation process, “X” is indicated. When no problem is confirmed, “○” is indicated.

"Float check"
The modules obtained in Examples and Comparative Examples were visually confirmed under a fluorescent lamp. When one or more omissions of 5 mmφ or more in the A4 size were confirmed in the photoelectric conversion cell 3, “X” was indicated.

  Therefore, as is clear from the above examples, in the case of one EVA layer as in Comparative Examples 5 to 7, the EVA layer floating in contact with the photoelectric conversion cell 3 is changed even if the thickness of the EVA layer is changed. Is confirmed, and the water vapor barrier property of the EVA layer cannot be improved.

  Next, even when the EVA layer and the ionomer layer had a two-layer structure, when the film thickness of the ionomer layer was 10 μm or less, the EVA layer in contact with the photoelectric conversion cell 3 was confirmed to float.

  Therefore, even if the EVA layer and the ionomer layer have a two-layer structure, if the ionomer layer has a thickness of 10 μm or more and does not exceed the thickness of the EVA layer, the evaluation of workability and floating confirmation is high. I can prove it.

  In addition, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention.

  DESCRIPTION OF SYMBOLS 1 ... Surface protection member (for example, white plate glass), 2-1 ... Sealing material sheet, 2-1a ... Main constituent member layer (EVA layer), 2-1b ... Subordinate constituent member layer (ethylene / unsaturated carboxylic acid) (Ionomer layer of copolymer), 3... Photoelectric conversion cell, 4... Back surface protection member (for example, vinyl fluoride polymer).

Claims (4)

In order to seal the photoelectric conversion cell disposed between the surface protection member and the back surface protection member, it is provided so as to sandwich the photoelectric conversion cell,
In a sealing material sheet used as a member of a solar cell obtained by laminating all members to form a laminated body, and thermocompression bonding the laminated body,
An encapsulant sheet comprising two layers composed of an EVA layer and an ionomer layer of an ethylene / unsaturated carboxylic acid copolymer.   An ionomer layer of an ethylene / unsaturated carboxylic acid copolymer for improving the water vapor barrier property of the EVA layer in contact with the photoelectric conversion cell is laminated on the side opposite to the sealing side surface of the EVA layer in contact with the photoelectric conversion cell. The sealing material sheet according to claim 1, which has a two-layer structure.   The ionomer layer of the ethylene / unsaturated carboxylic acid copolymer is 10 μm or more and has a thickness not exceeding the thickness of the EVA layer. The encapsulant sheet described in 1.   In order to seal a photovoltaic cell, the sealing agent sheet as described in any one of Claims 1-3 was used, The solar cell module characterized by the above-mentioned.

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