JP2003049004A - Flexible resin sheet, filler for solar cell and solar cell using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prepare a flexible resin sheet having excellent durability and adhesive strength without being crosslinked and especially useful for a solar cell, a filler for the solar cell, and to provide the solar cell using the filler. SOLUTION: The flexible resin sheet is characterized in that the shear modulus of elasticity is >=2×10<6> and <=1×10<7> Pa at 20 deg.C, >=5×10<4> Pa at 80 deg.C and >=3×10<3> and <=3×10<5> Pa at 120 deg.C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a soft resin sheet having excellent durability, and more particularly, to a filler for a solar cell used for fixing a solar cell in a solar cell module and bonding it to a light-receiving glass / rear sheet. Relates to a solar cell using.

[0002]

2. Description of the Related Art In recent years, solar cells have become popular as a power supply source. Along with this, a variety of installation environments and long-term durability have come to be required, and various members used for solar cells are required to be reliable for a long period of time in a severe environment.

[0003]

Conventionally, EVA (ethylene-vinyl acetate copolymer) type, PVB (polyvinyl butyral) type, silicone type and the like have been proposed as a filler for a solar cell, which is one of the members. .

The function of the filling material is to fix the cells and to join them together with the light-receiving glass and the back sheet, and in terms of adhesiveness, workability, and weather resistance, heat resistance, cold resistance, moisture resistance, and sun resistance in terms of long-term outdoor use. There are many requirements such as light transmittance depending on the type of battery.

In recent years, EVA systems have been widely used practically from the viewpoints of price, workability and moisture resistance.

However, when the EVA system is used for a long period of time, there arises a problem that the moisture resistance is deteriorated due to deterioration and deterioration such as yellowing, cracking, foaming, etc., which is one of the factors that cause a decrease in the amount of power generation due to the corrosion of cells. Was considered. These are EV
It is considered that the problem in the composition of the A system is that it is easily affected by the ester structure having high hydrolyzability. Utilizing the above advantages of EVA system,
As a proposal that suppresses the drawbacks, the inventor has disclosed the technology of systems other than EVA with ethylene resin (Japanese Patent Application No. 13-3351).
6).

[0007] According to these proposals, the corrosion of the cell caused by the compositional problem can be suppressed and can contribute to the reduction of the power generation amount. However, depending on the condition, the corrosion etc. progress due to the contribution other than the composition and the reduction of the power generation amount is prevented. In some cases, it is not possible.
As a result of diligent studies on various factors, the inventors have found that controlling the shear modulus at each temperature in which the filler for a solar cell is placed can solve the problem by suppressing the corrosion of the cells and the like, and reached the present invention. INDUSTRIAL APPLICABILITY The present invention has a soft resin sheet made of an ethylene resin, which has excellent performance equivalent to that of EVA resin, and solves the problem of deterioration / alteration even if corrosion due to contributions other than composition progresses, and a filler for solar cells. An object is to provide a material and a solar cell using the same.

[0008]

That is, the present invention is at 20 ° C.
At a shear modulus of 2 × 10 ⁶ Pa or more and 1 × 10 ⁷ Pa or less and a shear modulus at 80 ° C. of 5 × 10 ⁴ Pa or more and a shear modulus at 120 ° C. of 3 × 10 ³ Pa or more and 3 × 10 ⁵
A soft resin sheet characterized by having a content of Pa or less is proposed, which has a melting point of 80 ° C or higher and 120 ° C or higher by grafting at least 0.01% by mass or more of alkoxysilane.
A sheet comprising at least an ethylene-based resin having a shear modulus at 80 ° C. of 1 × 10 ⁶ Pa or more, and mainly composed of polyethylene, ethylene-α olefin copolymer or ethylene-acrylic ester copolymer. The sheet is made of at least the ethylene-based resin, and the alkoxysilane compound is added to
It includes a sheet in which a composition containing 01 mass% or more is laminated on at least one surface. Further, the present invention proposes a filler for a solar cell, which comprises a sheet in which the soft resin sheet is laminated on at least one side, and further the present invention contacts the filler for a solar cell with a light-receiving glass. The solar cell is characterized by being laminated and adhered to the surface opposite to the light receiving surface to form a module.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail.

The soft resin sheet in the present invention has a temperature of 20 ° C.
At a shear modulus of 2 × 10 ⁶ Pa or more and 1 × 10 ⁷ Pa or less at 80 ° C. and a shear modulus of 5 × 10 ⁴ Pa or more at 1
Shear rate at 20 ℃ is 3 × 10 ³ Pa or more 3 × 10 ⁵ Pa
It is the following. The shear elastic modulus at 20 ° C. is an index of physical properties under normal conditions and is related to workability, handling property, storability, and the like, and is one factor that determines the residual stress of a solar cell (module) after processing. If it is less than 2 × 10 ⁶ Pa, the residual stress after processing will be lower, but as a result, the cell corrosion after processing is suppressed in the solar cell and the decrease in power generation is suppressed, which is preferable, but the softening is severe and before heating during processing of the solar cell. The contact wetting during setting between the sheet and the cell is remarkable beyond the embossed design, and as a result, even if embossing is performed, defoaming during heating is insufficient and air bubbles remain and damage the appearance and power generation performance. The sheets cannot be rolled in a roll without air bubbles, or when they are unrolled, they adhere to each other and the peeling is heavy, which causes the sheets to deform, and it takes time and effort to set the cells and back sheet before processing the solar cells. If the period is long or the sheet is placed at a high temperature, self-adhesion proceeds, peeling becomes heavy, and excessive force is applied to deform the sheet. When it exceeds 1 × 10 ⁷ Pa, bubbles remain little during solar electroprocessing and there are few problems due to self-adhesion during handling, but residual stress after processing becomes large and corrosion easily occurs.

The shear modulus at 80 ° C. is an index of the physical properties under the environment where the solar cell is used and is related to the heat resistance during use. When it is less than 5 × 10 ⁴ Pa, the adhesion and holding of the back sheet and the cell are insufficient under high temperature in the midsummer to cause a shift, or the cohesive force is low and foaming occurs in the sheet, which is not preferable.

The shear modulus at 120 ° C. is an index of physical properties under processing of the module, and is related to fluidity and initial wettability of adhesion. When it is less than 3 × 10 ³ Pa, the initial wettability is good, but the fluidity becomes excessively large, and during processing, thinning due to extrusion or extrusion, the timing of fluidization is faster than the degassing rate through the embossed gap Degassing between the sheet and the cell during battery processing is insufficient and remains, easily causing deterioration in appearance and power generation. On the other hand, when it exceeds 3 × 10 ⁵ Pa, the fluidity is impaired and it does not flow in following the irregularities of the cell, and as a result, bubbles remain and the appearance and power generation performance are degraded, and the initial wettability of adhesion is insufficient. Therefore, the adhesiveness after processing the solar cell is impaired.

In the present invention, the shear modulus is a value measured by a dynamic viscoelasticity measuring device manufactured by Iwamoto Seisakusho under the condition of a period of 2πrad and an amplitude distortion of 0.5%.

The shear modulus is specifically defined by the resin material composition,
It can be controlled by the molecular weight, adjustment of additives, crosslinking / polymerization conditions, thermoforming conditions and the like.

Particularly, as the resin material, a polyolefin resin, a polyester resin, a poly (meth) acrylic acid ester resin, a polystyrene resin, a polyvinyl chloride resin, a polyurethane resin, an epoxy resin, a fluorine resin,
Silicone, polyether-based resin, polycarbonate-based resin, polyamide-based resin, etc. may be used alone or as a copolymer and / or blend of two or more of the same kind or different kinds or different kinds.
Alternatively, a laminated resin can be used.

More specifically, for example, the polyolefin resin will be specifically described later (B-1) to (B-).
Resins such as 6) and blends and / or laminating resins thereof can be used.

(B-1) Ethylene homopolymer or ethylene and an α-olefin having 3 to 20 carbon atoms as the second component, or an aliphatic unsaturated carboxylic acid or an aliphatic unsaturated carboxylic acid anhydride as the second and third components. Thing, an aliphatic unsaturated isocyanate, an aliphatic unsaturated amine, an aliphatic unsaturated amide, an aliphatic unsaturated epoxide, an aliphatic unsaturated alkoxysilane, a copolymer with an aliphatic polyunsaturated compound,
Here, as the α-olefin copolymerized with ethylene,
Examples include propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 3-methyl-1-butene, 4-methyl-1-pentene and the like. It The α-olefin and the aliphatic unsaturated compound to be copolymerized may be used alone or in combination of two or more. The α-olefin to be copolymerized with ethylene is usually 3 to 80% by mass. ,
The aliphatic unsaturated compound is usually 0.01 to 30% by mass.
What is used.

(B-2) Ethylene, vinyl acetate as the second component, aliphatic unsaturated monocarboxylic acid alkyl ester, and / or aliphatic unsaturated carboxylic acid as the third component, aliphatic unsaturated carboxylic acid anhydride , An ethylenic group consisting of a monomer selected from aliphatic unsaturated isocyanate, aliphatic unsaturated amine, aliphatic unsaturated amide, aliphatic unsaturated epoxide, aliphatic unsaturated silane, and aliphatic polyunsaturated compound Copolymers, more specifically, ethylene-acrylic acid copolymers, ethylene-methacrylic acid copolymers, ethylene-acrylic acid esters (alcohols having 1 to 8 carbon atoms such as methyl, ethyl, propyl and butyl) Copolymers, ethylene-methacrylic acid esters (methyl, ethyl, propyl, butyl and like alcohols having 1 to 8 carbon atoms). A copolymer or the like, which is a multi-component copolymer of three or more components (for example, ethylene, an aliphatic unsaturated carboxylic acid and the same ester). 3 chosen
It may be a copolymer of the above or the like). The content of the carboxylic acid ester group copolymerized with ethylene is usually 3
˜50% by mass, and the aliphatic unsaturated compound is usually 0.01 to 30% by mass. The problem of can be improved.

(B-3) α-of ethylene, propylene, etc.
A metal salt of a copolymer composed of a monomer selected from olefins and aliphatic unsaturated carboxylic acids (preferred metal is Zn,
Na, K, Li, Mg, etc.).

(B-4) Homopolymer of propylene or random copolymer or block copolymer with other monomer copolymerizable with propylene. Further, the three-dimensional structure thereof is not particularly limited, and may be a polymer having a structure of isotactic, atactic, syndiotactic or a mixture thereof. Other copolymerizable monomers include ethylene, butene-1, hexene-1, 4-methyl-pentene-1, octene-1 and other α-olefins having 4 to 12 carbon atoms and divinylbenzene, 1, Dienes such as 4-cyclohexadiene, dicyclopentadiene, cyclooctadiene, ethylitene norbornene and the like can be used, and among these, ethylene is preferable.

Examples of the random copolymer include propylene-ethylene random copolymer and propylene-ethylene-butene-1 copolymer, and the block copolymer includes propylene-ethylene block copolymer. It can be used for reactor type polypropylene elastomer.

(B-5) One or more but not less than 70 mol% butene-1 crystalline other monomer (ethylene, propylene, and α-olefin having 5 to 8 carbon atoms). Copolymer of.

(B-6) 4-Methyl-1-pentene and / or 3-methyl-1-pentene homopolymer or other monomer copolymerizable therewith (carbon other than methyl-1-pentene) Copolymer with 2 to 20 α-olefins, etc.).

The molecular weight of the resins (B-1) to (B-6) is 5,000 or more after the module processing,
It is preferably 10,000 or more.

As additives, a weather resistance stabilizer, a heat resistance stabilizer, an antistatic agent, an antiblocking agent, a lubricant, a nucleating agent, a plasticizer, an antiaging agent, a hydrochloric acid absorbent, as long as the object of the present invention is not impaired. Further, additives such as an antioxidant, an inorganic filler, an organic filler, a crosslinking agent, a polymerization inhibitor and a catalyst may be appropriately mixed. Further, within the scope of the present invention, for example, in the case of the polyolefin resin of the above-mentioned example, if necessary for the purpose of further improving the recycled resin and various physical properties generated from trimming loss, petroleum resins, paraffin System oils, liquid polybutene, copolymers of vinyl aromatic compounds and conjugated dienes (block and random) or hydrogenated derivatives thereof, copolymers of aromatic monomers with ethylene and / or other α-olefins, etc. You may add and mix. Nucleating agents, plasticizers, fillers, petroleum resins, paraffinic oils, cross-linking agents and the like can be used as agents that can be adjusted particularly effectively.

The sheet is particularly preferably at least 0.
At least an ethylene-based resin grafted with 01% by mass or more of alkoxysilane is used.

As the alkoxysilane to be grafted, an aliphatic unsaturated silane such as vinylalkoxysilane is used, which is previously added to the ethylene resin by a graft reaction using a functional group such as a vinyl group. The graft amount is 0.0
If the amount is 1% by mass or more and the amount is less than 1% by mass, the adhesiveness to the light-receiving glass and the cell is impaired. The graft amount can be controlled by the graft reaction conditions such as the amount and type of alkoxysilane, reaction temperature, time, catalyst, additives such as swelling agent and the like. An ethylene-based resin grafted with alkoxysilane can be used as a filler for solar cells with a single sheet, but only the front side that contacts the cell, light-receiving glass, and back sheet is the same resin and polyethylene or ethylene on the opposite side (in some cases, the core side). A sheet in which an ethylene-based resin mainly containing an α-olefin copolymer is adhesively laminated may be used. Alternatively, it may be a sheet made of a blend of two or more kinds thereof, or a blend of an ethylene resin other than the ethylene resin grafted with the alkoxysilane.

Furthermore, within the range that does not impair the above contents, a light stabilizer, an ultraviolet absorber, an antioxidant, a processing aid,
Various additives including a cross-linking agent may be added within the same range as described above without exceeding the degree of deterioration due to the contribution of the crystal nucleating agent, which does not include a hydrolyzable ester structure.

Further, the sheet is particularly preferably a sheet containing at least an ethylene resin mainly composed of polyethylene or an ethylene-α-olefin copolymer or an ethylene-acrylic acid ester copolymer. By applying polyethylene and ethylene-α-olefin copolymer, the contribution of hydrolyzability, which is one of the compositional problems in the EVA system that has been conventionally used, can be eliminated, and a favorable result in durability can be obtained. Further, by applying the ethylene-acrylic acid ester copolymer, the hydrolyzability can be made to a low level, and the effect of improving the durability can be obtained. As the ethylene-based resin, various additives such as a light stabilizer, an ultraviolet absorber, an antioxidant, a processing aid, a crystal nucleating agent, etc. can be added within a range that does not impair the above and the following contents. When the polymer is not contained, a crosslinking agent can be added to the extent that the ester structure having high hydrolyzability is not contained and the degree of deterioration due to the contribution is not exceeded.

Furthermore, the sheet is particularly preferably a sheet having a composition containing 0.01% by mass or more of an alkoxysilane compound laminated on at least one side. Examples of the alkoxysilane compound include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetraisopropoxysilane, tetraalkoxysilanes such as tetrabutoxysilane, methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, and methyltributoxy. Silane, ethyltrimethoxysilane, ethyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, isopropyltrimethoxysilane, isopropyltriethoxysilane,
Vinyltrimethoxysilane, vinyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3
-Glycidoxypropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, 3,4-epoxycyclohexylethyltrimethoxysilane, 3,4- Trialkoxysilanes such as epoxycyclohexylethyltrimethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, diethylmethoxysilane, diethylethoxysilane, or partial condensates thereof may be used. The content is 0.01% by mass or more, and if the content is less than that, the adhesiveness with the light-receiving glass and the cell is impaired.

The alkoxysilane compound may be used alone or dispersed in a resin solution, a resin emulsion, a thermoforming resin or the like.

The sheet can be processed by a commonly used molding method such as a coating method, a calendering method and an extrusion method, but is not particularly limited. Particularly preferred are ethylene-based resins grafted with an alkoxysilane, polyethylene or ethylene-based resins mainly composed of ethylene-α-olefin copolymers or ethylene-acrylic acid ester copolymers, and thermoplastic molding methods such as calendering and extrusion. Can be processed by. When the processing conditions include alkoxysilane, the processing temperature is lower than the reaction temperature, and the alkoxysilane needs to be in an unreacted state immediately after the sheet molding. In particular, in order to make the processing conditions of the solar cell module mild, the processing temperature is further lowered when the alkoxysilane reaction catalyst is added.

In the case of a laminated system, a solution coating method, a co-extrusion method, an extrusion coating method, a hot roll laminating method or the like can be used as the processing method for the second and subsequent layers.

The thickness of the sheet is 5 according to the fixing such as following the unevenness of the cell and the follow-up of the undulation of the light-receiving glass / backside sheet.
0 to 1000 μm, preferably 100 to 600 μm.
In the case of a laminated system, the total thickness is the same and the composition containing 0.01 mass% or more of the ethylene resin and the alkoxysilane compound grafted with the alkoxysilane is 0.1 to 100 μm, preferably 1 to 30 μm.

The surface of the sheet may be embossed in order to suppress air bubbles remaining between various layers during module processing.

The above sheet can be made into a solar cell (module) by laminating from various member settings in the same process as the conventional filler. In particular, the cross-linking step can be omitted, so that the temperature can be reduced and the time can be shortened, the manufacturing efficiency can be increased, and the stress such as residual stress can be suppressed to be low, which is advantageous in durability.

Further, as compared with the conventional EVA system, the harmful effects under various environments are suppressed to be low, and as a result, there is an improvement effect in reliability. Next, an example of the solar cell of the present invention will be described in more detail with reference to the drawings. FIG. 1 is a schematic sectional view showing an example of the solar cell of the present invention, and FIG. 2 is a schematic sectional view showing another example of the solar cell of the present invention. In FIG. 1, the present invention is characterized in that a solar cell filler 1 made of a specific soft resin sheet is brought into contact with a light receiving glass 2 and laminated and adhered to a surface 21 opposite to a light receiving surface 20 to form a module. It is a solar cell that does. Here, the solar battery cells 3 are adhesively fixed so as to be sandwiched by the solar cell filler 1 from both sides of the cell light receiving surface 30 and the cell non-light receiving surface 31, and are protected by the back sheet 4. In FIG. 2, the solar cell 3 is a cell light-receiving surface 3
0 is adhered to the surface 21 opposite to the light-receiving surface of the light-receiving glass, and the solar cell filler 1 is laminated and adhered so as to extend over the surface 21 opposite to the cell non-light-receiving surface 31, and is modularized. It is protected by the sheet 4.

[0038]

EXAMPLES The present invention will be specifically described below with reference to examples.

Example 1 90 parts by mass of an ethylene octene copolymer having a melting point of 60 ° C. and an MI (melt index) of 30 g / 10 minutes (190 ° C. 2.16 kg) and a melting point of 118 ° C., MI1
10 parts by mass of an ethylene butene copolymer of g / 10 minutes, 0.5 parts by mass of a hindered amine light stabilizer, and 0.1 parts by mass of a phenolic antioxidant as a core layer, melting point 100 ° C., MI 10 g /
10 minutes trimethylsilane-modified ethylene α-olefin copolymer surface layer 2 type 3 layer constituent material is extruded at 150 ° C. into a 300 μm thick soft resin sheet after hot melt molding and pressed between embossing rolls before cooling. It was transferred and made into a sheet with minute irregularities on the surface. The core layer was 280 μm and the surface layer was 10 μm each. 20, 80, 120 of this sheet
Shear modulus at each temperature of ℃ is 4 × 10 ⁶ , 6 ×
It was 10 ⁴ , 5 × 10 ³ Pa. This sheet is a 3 mm thick float glass (= equivalent to light receiving glass 2), an aluminum layer vacuum-deposited on the float glass (= equivalent to solar cell 3), the sheet, (= equivalent to filler 1 for solar cell) ) 0.
Easily surface-adhesive polyvinyl fluoride / aluminum foil laminated film (= equivalent to back sheet 4) with a thickness of 08 mm was set in this order and vacuum heated at 130 ° C for 20 minutes in a heat-resistant rubber bag.
By pressure processing, a sample for evaluation corresponding to a solar cell module was prepared, and the following processability evaluation and durability test / evaluation were performed.

<Evaluation of workability> (1) Presence or absence of protrusion (visual inspection) ◯: No protrusion of the periphery of the filler, slight ×: Significant protrusion of periphery of the filler (2) Presence or absence of bubbles (visual inspection) ○: No bubble generation × : Remaining air bubbles (3) Adhesive strength: The adhesive strength of the folds peeled off 180 from each surface at 23 ° C and 5 mm / min is ○: 1 kg / cm or more ×: Less than 1 kg / cm or more, all are ○, otherwise It was comprehensively evaluated as x.

The result was ◯.

<Durability Test / Evaluation> (1) 2000 hours static treatment with a sunshine weather meter (2) 2000 hours static treatment in 85 ° C. 85% RH atmosphere (JIS C8917) Filler layer visually after each treatment The following four-level evaluation was carried out by comparing 12 items each of 6 tests with a total of 12 items of 2 tests of yellowing, cracking, foaming, presence of peeling from glass and back sheet, and presence of corrosion of aluminum layer. .

◯: No change or slight change within 3 items in comparison of 12 items, no large change Δ: 4 change or more in slight comparison in comparison of 12 items,
No major change x: 8 items or more in slight change in comparison of 12 items,
There was a big change and the result was ○.

Example 2 Melting point 84 ° C., MI 20 g / 10
100 parts by weight of an alkoxysilane-modified ethylene-ethyl acrylate copolymer, a hindered amine light stabilizer of 0.
5 parts by mass, 0.1 parts by mass of phenolic antioxidant 18 parts
After extruding at 0 ° C. into a sheet having a thickness of 300 μm, the sheet was subjected to pressure transfer between the embossing rolls after hot-melt molding and before cooling to obtain a sheet having fine irregularities on the surface. 20, 8 of this sheet
Shear modulus at 0 and 120 ° C is 9 × 1 each
It was 0 ⁶ , 6 × 10 ⁵ , and 6 × 10 ³ Pa.

Similarly, samples for evaluation corresponding to the solar cell module were prepared and tested and evaluated in the same manner as in (Example 1).

As a result, <workability evaluation> was ◯, and <durability evaluation> was ◯.

Example 3 50 parts by mass of an ethylene octene copolymer having a melting point of 60 ° C. and an MI (melt index) of 30 g / 10 minutes (190 ° C. 2.16 kg) and a melting point of 122 ° C., MI1
50 parts by weight of an ethylene butene copolymer of g / 10 minutes, 0.5 parts by weight of a hindered amine-based light stabilizer, and 0.1 parts by weight of a phenolic antioxidant at 180 ° C. were used to make a thickness of 3
After heat-melt molding and before cooling to a sheet of 00 μm, pressure transfer was performed between embossing rolls to obtain a sheet having fine irregularities on the surface. Both sides of this sheet were coated with a mixed toluene solution of 100 parts by mass of hydrogenated rosin ester having a softening point of 100 ° C. and 10 parts by mass of γ-glycidoxypropyltrimethoxysilane and then dried to form a layer of 2 μm. The shear modulus of elasticity of this sheet at 20, 80, and 120 ° C. was 1 × 10 ⁷ , 9 × 10 ⁵ , and 3 × 10 ⁴ Pa, respectively. In the same manner as in (Example 1), a sample for evaluation corresponding to a solar cell module was prepared and tested / evaluated.

As a result, <Workability evaluation> was ◯, and <Durability evaluation> was ◯.

Example 4 A commercially available heat-crosslinkable EVA-based sheet (400 μm) was used to perform vacuum heating and pressure processing in a heat-resistant rubber bag at 130 ° C. for 20 minutes, and then in an oven at 150 ° C.
Except for heating EVA for 20 minutes to crosslink EVA (Example 1)
Similarly to the above, a sample for evaluation corresponding to the solar module was prepared and tested and evaluated. The sheet was subjected to a crosslinking treatment under the same temperature condition, and the shear modulus at each temperature of 20, 80 and 120 ° C. was measured to be 3 × 10 ⁶ , 3 × 1 respectively.
It was 0 ⁵ , 2 × 10 ⁵ Pa. As a result, <Workability evaluation> was ○, and <Durability evaluation> was Δ.

(Comparative Example 1) A commercially available heat-crosslinkable EVA-based sheet (400 μm) different from that used in Example 4 was used to perform crosslinking in the same manner as in Example 4, and the same test evaluation was performed. Crosslinking is performed under the same temperature condition, and 2
The shear elastic moduli at 0, 80 and 120 ° C. were measured and found to be 7 × 10 ⁶ , 6 × 10 ⁵ and 6 × 10 ⁵ Pa, respectively. As a result, <Workability evaluation> was O, and <Durability evaluation> was X.

In particular, the corrosion of the aluminum layer in <Durability Evaluation> was remarkable. There was also an acetic acid odor after the test.

Comparative Example 2 100 parts by weight of an ethylene octene copolymer having a melting point of 49 ° C. and an MI (melt index) of 0.5 g / 10 minutes (190 ° C. 2.16 kg) and 0.5 part by weight of a hindered amine light stabilizer. , 0.1 parts by mass of phenolic antioxidant as a core layer, melting point 84 ° C., MI 20 g / 10 min, alkoxysilane-modified ethylene ethyl acrylate copolymer as a surface layer, a two-kind three-layer constituent material was extruded at 150 ° C. Due to thickness 3
After heat-melt molding and before cooling to a sheet of 00 μm, pressure transfer was performed between embossing rolls to obtain a sheet having fine irregularities on the surface. The core layer was 280 μm and the surface layer was 10 μm each.
The shear modulus of elasticity of this sheet at 20, 80, and 120 ° C. was 1 × 10 ⁶ , 2 × 10 ⁴ , and 1 × 10 ³ Pa, respectively. In the same manner as in (Example 1), a sample for evaluation corresponding to a solar cell module was prepared and tested / evaluated.

As a result, <workability evaluation> was x, and <durability evaluation> was x. Especially in the case of <workability evaluation>,
Air bubbles were remarkable, and foaming and peeling (deviation) in <Durability evaluation> were remarkable.

Comparative Example 3 100 parts by mass of low-density polyethylene having a melting point of 112 ° C., MI (melt index) of 0.7 g / 10 min (190 ° C. 2.16 kg), 0.5 part by mass of a hindered amine light stabilizer, and phenol. A two-layer, three-layer constituent material having 0.1 parts by mass of a antioxidant as a core layer, a melting point of 100 ° C., and a trimethylsilane-modified ethylene α-olefin copolymer having a MI of 10 g / 10 min as a surface layer at 200 ° C. by an extrusion method. 300
After heat-melt molding on a sheet having a thickness of μm, the sheet was pressure-transferred between embossing rolls before cooling to obtain a sheet having fine irregularities on the surface. The core layer was 280 μm and the surface layer was 10 μm each. The shear elastic moduli of the sheet at temperatures of 20, 80, and 120 ° C. were 3 × 10 ⁷ , 7 × 10 ⁶ , and 4 × 10 ⁴ Pa, respectively. In the same manner as in (Example 1), a sample for evaluation corresponding to a solar cell module was prepared and tested / evaluated.

As a result, <workability evaluation> was x, and <durability evaluation> was x. In particular, the adhesive strength was slightly lower in <Workability evaluation>, the aluminum layer was significantly corroded in <Durability evaluation>, and the shrinkage in the in-plane direction of the filler was also slightly observed. Presence and its effect during the durability test were confirmed.

[0056]

EFFECTS OF THE INVENTION The soft resin sheet of the present invention is excellent in durability and exerts an adhesive force without cross-linking.
Since low temperature and short time are possible, manufacturing efficiency is improved,
In addition, since the laminating conditions are mild, stress such as residual stress can be suppressed low, which is advantageous in durability. As described above, the solar cell filler mainly composed of the soft resin sheet of the present invention has less harmful effects under various environments as compared with the conventional EVA resin filler, resulting in the reliability of the solar cell module. The effect that the property is greatly improved is exhibited.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing an example of a solar cell of the present invention.

FIG. 2 is a schematic cross-sectional view showing another example of the solar cell of the present invention.

[Explanation of symbols]

1 Sheet for solar cell filler 2 Light receiving glass 20 Light receiving surface 21 Surface opposite to the light receiving surface 3 solar cells 30 cell light receiving surface 31 cell non-light-receiving surface 4 Back sheet

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 4F071 AA18 AA33 AA76 AA77 AA80                       AF20Y AH15 BC01                 4F100 AH06A AH06B AH06C AK04A                       AK25A AK62A AL01A AL04A                       BA02 BA03 BA06 BA07 EH46                       EJ86 GB48 JA04A JK07A                       JK13A JL11 YY00A YY00B                       YY00C                 5F051 BA14 BA15 JA04

Claims (6)

[Claims] 1. The shear modulus at 20 ° C. is 2 × 10.
^{It is characterized} in that the shear elastic modulus at 80 ° C. is 5 × 10 ⁴ Pa or more and the shear elastic modulus at 120 ° C. is 3 × 10 ³ Pa or more and 3 × 10 ⁵ Pa or less at ⁶ Pa or more and 1 × 10 ⁷ Pa or less. Soft resin sheet consisting of sheets. 2. A melting point of 80 ° C. or higher and 120 ° C. by grafting at least 0.01% by mass or more of alkoxysilane.
2. The soft resin sheet according to claim 1, wherein the soft resin sheet comprises at least an ethylene resin having a shear modulus at 80 ° C. of 1 × 10 ⁶ Pa or more. 3. The soft resin sheet according to claim 1, comprising a sheet containing at least an ethylene-based resin mainly composed of polyethylene, an ethylene-α-olefin copolymer or an ethylene-acrylic acid ester copolymer. 4. The soft resin sheet according to claim 1, which comprises a sheet in which a composition containing 0.01 mass% or more of an alkoxysilane compound is laminated on at least one surface. 5. A filler for a solar cell, comprising the soft resin sheet according to any one of claims 1 to 4. 6. A solar cell, characterized in that the solar cell filler according to claim 5 is brought into contact with a light-receiving glass and laminated and adhered to the surface opposite to the light-receiving surface to form a module.