WO2016125793A1

WO2016125793A1 - Solar cell sealing film, solar cell sealing film roll, and method for manufacturing solar cell module

Info

Publication number: WO2016125793A1
Application number: PCT/JP2016/053059
Authority: WO
Inventors: 貴信室伏; 徳弘　淳; 昌道徳武
Original assignee: 三井化学東セロ株式会社
Priority date: 2015-02-04
Filing date: 2016-02-02
Publication date: 2016-08-11
Also published as: KR20170101257A; CN107343383A; JPWO2016125793A1

Abstract

A plurality of recessed sections (100) are arranged in a lattice shape and formed on at least one surface of a film (10). The average depth of the plurality of recessed sections (100) is 50-200 μm. On the at least one surface, when the apparent surface area when the surface is flat is defined as S_a, and the surface area of the top surface (110) on which the plurality of recessed sections (100) are not formed is defined as S_t, the proportion of area of the top surface (110) represented by S_t/S_a×100(%) is 10% or less.

Description

Solar cell sealing film, solar cell sealing film roll, and solar cell module manufacturing method

The present invention relates to a solar cell sealing film, a solar cell sealing film roll, and a method for manufacturing a solar cell module.

Patent Document 1 describes a solar cell sealing film made of an embossed ethylene-vinyl acetate copolymer resin film. In Patent Document 1, the film is provided with recesses by embossing, and the percentage V of the total volume V _H of the recesses per unit area of the film and the apparent volume V _A of the unit area multiplied by the maximum thickness V _H / _VA × 100% is 5 to 80%. By doing so, a cushioning property is imparted to the film at the time of heat processing in the sealing process when the solar cell is manufactured, and damage to the solar cell is prevented, and deaeration failure is prevented.

Japanese Patent No. 3473605

However, Patent Document 1 states that regarding the depth of the recess formed by embossing, the depth ratio with respect to the maximum thickness t _max of the film is emphasized, and the depth ratio is preferably 20 to 95%. Yes. Therefore, when the thickness of the film is increased, the area occupied by the recesses is inevitably reduced in order to maintain a specific porosity. And according to examination of inventors, in the film as described in patent document 1, when storing as a film roll etc., it is clear that blocking may occur between film surfaces which contact each other. became.

The present invention provides a film for sealing a solar cell that is less likely to cause blocking between film surfaces during transportation and storage, and that is excellent in air bleedability in the production of a solar cell module.

As a result of intensive studies to achieve the above-mentioned problems, the inventors have adjusted the average depth of the recesses and the area ratio of the upper surface of the film, so that blocking between the film surfaces during transportation and storage is less likely to occur. The inventors have found that a solar cell sealing film having excellent air release properties can be obtained in the production of solar cell modules, and have completed the present invention.

That is, according to the present invention, the following solar cell sealing film is provided.

[1]
On at least one surface, a plurality of recesses are formed in a grid pattern,
The average depth of the plurality of recesses is 50 μm or more and 200 μm or less,
In at least one surface, when the apparent surface area of the case where the surface is to be flat and the S _a, the area of the upper surface of the plurality of recesses are not formed _{_{_{S t, S t / S a}}} × 100 (% The film for solar cell sealing whose area ratio of the said upper surface represented by this is 10% or less.
[2]
In the solar cell sealing film according to the above [1],
The film for solar cell sealing whose period of the arrangement | sequence of the said several recessed part is the range of 500 to 2000 micrometers.
[3]
In the film for sealing a solar cell according to the above [1] or [2],
The film for sealing a solar cell, wherein the upper surface and the surfaces constituting the plurality of recesses intersect at 30 ° or more and 60 ° or less.
[4]
In the film for sealing a solar cell according to any one of [1] to [3],
The plurality of recesses are square, rectangular, rhombus, parallelogram, triangle, or hexagon in plan view, and are filled with at least one surface at a certain distance from each other.
[5]
The film roll for solar cell sealing formed by the film for solar cell sealing as described in any one of said [1] to [4] being wound up by the core material.
[6]
A preparation step of preparing a film for sealing solar cells;
While laminating the surface side transparent protective member, the first solar cell sealing film, the solar battery cell, the second solar cell sealing film, and the back surface protective member in this order, to form a laminate, Sealing and integrating the laminate by heating and pressing,
In the first and second solar cell sealing films, a plurality of recesses are arranged in a lattice pattern on at least one surface,
The average depth of the plurality of recesses is 50 μm or more and 200 μm or less,
In at least one surface, when the apparent surface area of the case where the surface is to be flat and the S _a, the area of the upper surface of the plurality of recesses are not formed _{_{_{S t, S t / S a}}} × 100 (% The manufacturing method of the solar cell module whose area ratio of the said upper surface represented by this is 10% or less.

According to the present invention, it is possible to provide a solar cell sealing film that is less likely to cause blocking between film surfaces during transportation and storage, and that is excellent in air bleedability in the production of solar cell modules.

The above-described object and other objects, features, and advantages will be further clarified by a preferred embodiment described below and the following drawings attached thereto.

It is a figure which shows the structure of the film for solar cell sealing which concerns on this embodiment. FIG. 2 is a cross-sectional view observed in the direction indicated by an arrow in the drawing from the cross section of the alternate long and short dash line AA shown in FIG. It is a figure which shows the example of the structure of the film for solar cell sealing which a recessed part is an equilateral triangle and arranged in the triangular lattice form. It is sectional drawing which shows the example of the structure of the film for solar cell sealing in case a recessed part consists of a curved surface. It is a figure for demonstrating the example of the position which cuts out a film piece from the film roll for solar cell sealing which made the film for solar cell sealing into the roll shape. It is a cross-sectional schematic diagram explaining the process of the manufacturing method of the solar cell module which concerns on embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, the same reference numerals are given to the same components, and the description will be omitted as appropriate.

Note that “~” represents the following from the above unless otherwise specified.

FIG. 1 is a diagram showing a structure of a solar cell sealing film 10 (hereinafter referred to as “film 10”) according to the present embodiment. FIG. 2 is a plan view of the film 10, and FIG. 2 is a cross-sectional view of the cross section taken along the alternate long and short dash line AA shown in FIG.

The film 10 according to the present embodiment is formed with a plurality of concave portions 100 arranged in a lattice pattern on at least one surface. And the average depth of the some recessed part 100 is 50 micrometers or more and 200 micrometers or less. Further, in at least one surface, when the apparent surface area S _a when the surface has to be _flat, the area of the upper surface 110 a plurality of recesses 100 are not formed as _{_{_{S t, S t / S a}}} × The area ratio of the upper surface 110 represented by 100 (%) is 10% or less. This will be described in detail below.

The film 10 is transported and stored, for example, as a solar cell sealing film roll formed by winding the film 10 around a core material. The film 10 is not limited to a roll shape, and may be stacked and transported and stored.

A plurality of recesses 100 are provided on one side or both sides of the film 10. The plurality of recesses 100 are arranged in a lattice pattern, and are filled with a certain distance from each other. Here, the lattice shape is not limited to a square lattice but may be an array according to a lattice such as an orthorhombic lattice, a triangular lattice, or a hexagonal lattice. From the viewpoint of effectively suppressing blocking between film surfaces, the recess 100 is preferably formed over the entire surface of at least one surface of the film 10.

The shape of the plurality of recesses 100 is not particularly limited, but from the viewpoint of efficiently filling the surface and from the viewpoint of ease of formation of the recesses 100, a square, rectangle, rhombus, parallelogram, triangle, or six in plan view A rectangular shape is preferred. In addition, when the recessed part 100 is a triangle, it is more preferable that it is a regular triangle or an isosceles triangle. Here, the shape of the concave portion 100 in plan view is a shape determined by a line where the concave portion 100 and the upper surface 110 intersect, that is, the outline 104 of the concave portion 100.

Here, the upper surface 110 is a region where the concave portion 100 is not formed on the surface of the film 10 where the concave portion 100 is formed, that is, the top surface of the convex ridge portion. The film 10 wound up or stacked on the film roll 20 comes into contact with the adjacent film surface at the portion of the upper surface 110.

FIG. 1 shows an example in which the recesses 100 are square and arranged in a square lattice pattern.
On the other hand, FIG. 3 is a diagram showing an example of the structure of the film 10 in which the recesses 100 are equilateral triangles and arranged in a triangular lattice pattern as a modification.

In the film 10, the average depth of the plurality of recesses 100 is 50 μm or more and 200 μm or less, more preferably 80 μm or more and 200 μm or less, and further preferably 100 μm or more and 200 μm or less. Here, the depth d of each recessed part 100 is the maximum depth of the recessed part 100 with respect to the upper surface 110, and the average depth of the several recessed part 100 is an average value of the depth d. In the production of a solar cell module, after stacking other components on the solar cell sealing film, air may remain in the recesses and bubbles may be generated in the laminate when being integrated by heating and pressurization. If the average depth is less than or equal to the above upper limit, air is less likely to be trapped when the irregularities are crushed by heating and pressurization, that is, the air is easily removed and bubbles are reduced. Further, if the average depth is equal to or less than the above upper limit, when a film roll or the like is used, a useless space inside the film can be reduced, and transportation efficiency is improved. On the other hand, if the average depth is equal to or more than the above lower limit, the bottom surface of the recess 100 is unlikely to contact the adjacent film surface, and blocking between the film surfaces can be effectively suppressed. Incidentally, the average depth of the recess 100 is a range that does not exceed the maximum thickness _{t max} of the film 10 to be described later is preferably 50% or less of the maximum thickness _{t max} of the film 10, less than 40% of the maximum thickness _{t max} of the film 10 Is more preferable.

In FIG. 2, the recessed part 100 has shown the example which is a structure which has a plane slope and a bottom face. In this case, the shape of the recess 100 made of the outer shell 104 and the shape made of the outer shell 102 on the bottom surface may be the same or different from each other.
On the other hand, FIG. 4 is sectional drawing which shows the example of the structure of the film 10 in case the recessed part 100 consists of curved surfaces as a modification. Again, the depth d of each recess 100 can be defined as the maximum depth of the recess 100 relative to the upper surface 110.

The average depth of the recessed part 100 can be calculated | required, for example by observing a cross section of the film piece of the film 10 with an electron microscope.
FIG. 5 is a diagram for explaining an example of a position at which a film piece 200 is cut out from a solar cell sealing film roll 20 (hereinafter referred to as “film roll 20”) in which the film 10 is rolled. In this figure, the center line of the film roll 20 in the width direction is indicated by a one-dot chain line. Specifically, first, 20 mm × 20 mm square film pieces 200 are cut out at the center of the film roll 20 and at three locations 10 cm inside from both ends in the width direction as shown in the figure. And the depth d of each recessed part 100 in these film pieces 200 is measured by the cross-sectional observation with an electron microscope 10 pieces per one film piece 200, and those average values are calculated, The plurality of recessed parts 100 are calculated. Average depth can be determined.

Next, returning to FIGS. 1 and 2, the area ratio of the upper surface 110 will be described. On the surface of the film 10 where the recess 100 is formed, the area ratio of the upper surface 110 is 10% or less, more preferably 8% or less. If the said area ratio is below the said upper limit, since the contact area of the film surfaces which oppose can be reduced, blocking of film surfaces can be suppressed effectively. On the other hand, the area ratio of the upper surface 110 can be, for example, 1% or more, preferably 2% or more, more preferably 4% or more.

Here, the area ratio of the upper surface 110, when the apparent surface area S _a when the surface has to be _flat, the area of the upper surface 110 a plurality of recesses 100 is not formed and the S _t, S _t _/ S It is a value represented by _a × 100 (%). That is, the apparent surface area S _a is the width to a value obtained by multiplying the length of the film of the film, the area S _t of the upper surface 110 is the area of the region of the upper surface 110 shown in FIGS. 1 and 2 . The area ratio of the upper surface 110 can be adjusted by adjusting the distance between the recesses 100 or the width of the upper surface 110.

The area ratio of the upper surface 110 can be obtained, for example, by observing the film piece 200 of the film 10 with an optical microscope. Specifically, first, similarly to the evaluation of the average depth of the recess 100, square film pieces 200 of 10 mm × 10 mm are cut out from the three locations shown in FIG. And the surface shape of these film pieces 200 is measured with an optical microscope, the area ratio of the upper surface 110 is calculated, and the average value of the three film pieces 200 can be obtained as the area ratio of the upper surface 110.

The period p of the arrangement of the plurality of recesses 100 is preferably in the range of 500 μm to 2000 μm, more preferably in the range of 500 μm to 1500 μm, and still more preferably in the range of 500 μm to 1200 μm. The period p need not be the same throughout the film 10. If the period p is less than or equal to the above upper limit, the bottom of the recess 100 is unlikely to contact the adjacent film surface. Therefore, blocking can be effectively suppressed. On the other hand, if the period p is equal to or greater than the lower limit, the film 10 is excellent in air bleeding.

Here, the period p is the distance between the centers of gravity of one recess 100 and the recess 100 adjacent thereto, as shown in FIGS. Note that the center of gravity of the recess 100 is the center of gravity of the shape of the recess 100 determined by the outer shell 104. When there are a plurality of center-to-center distances between adjacent recesses 100 with respect to one recess 100, the minimum center-to-center distance may be within the above range, but the minimum center-to-center distance and the maximum center-to-center distance are Both are more preferably in the above range.

The period p can be obtained, for example, by observing the film piece 200 of the film 10 with an optical microscope. Specifically, first, similarly to the evaluation of the average depth of the recess 100, square film pieces 200 of 5 mm × 5 mm are cut out from the three locations shown in FIG. And the surface shape of these film pieces 200 is measured with an optical microscope, the period is measured, and it can be confirmed whether it exists in the said range.

It is preferable that the upper surface 110 of the film 10 and the surfaces constituting the plurality of recesses 100 intersect at 30 ° or more and 60 ° or less. That is, in the cross-sectional shape of the recess 100 perpendicular to the film surface, it is preferable that an angle r formed by the recess 100 and the upper surface 110 at an intersection of 30 ° or more and 60 ° or less. Specifically, for example, it is preferable that the angle r formed by the recess 100 and the upper surface 110 shown in FIGS. 2 and 4 is within the above range. As shown in FIG. 2, when the recess 100 has a flat slope, the angle r is an angle formed between the upper surface 110 and the slope. On the other hand, when the concave portion 100 is a curved surface as shown in FIG. 4, the angle r is an angle formed between the tangent to the curved surface and the upper surface 110 at the point where the concave portion 100 and the upper surface 110 intersect. If the angle r is not more than the above upper limit, the yield of forming the recesses 100 on the film 10 is improved. On the other hand, if it is more than the said minimum, blocking can be suppressed effectively.

The angle r can be obtained, for example, by observing a cross section of the film piece 200 of the film 10 with an electron microscope. Specifically, first, similarly to the evaluation of the average depth of the concave portion 100, square film pieces 200 of 20 mm × 20 mm are cut out from the three locations shown in FIG. Then, the angle r between each of the concave portions 100 and the upper surface 110 in these film pieces 200 is measured by cross-sectional observation with an electron microscope at 10 pieces per film piece, and it can be confirmed whether or not it is in the above range.

From the viewpoint of the balance between air release properties and cushioning properties when manufacturing the solar cell module, in the film 10, the ratio V _H /% of the total volume V _H of the recesses per unit area of the film and the apparent volume V _A of the film The porosity P (%) represented by V _A × 100 is preferably 3 to 30%, and more preferably 10 to 28%. The apparent volume _VA of the film is obtained by multiplying the unit area by the maximum thickness of the film 10.

The porosity P can be obtained by the following calculation. The apparent volume V _A (mm ³ ) of the film in which the recess is formed is determined by the product of the maximum thickness t _max (mm) of the film and the unit area (for example, 1 m ² = 1000 × 1000 = 10 ⁶ mm ² ), It is calculated as in the following formula (3).
V _A (mm ³ ) = t _max (mm) × 10 ⁶ (mm ² ) (3)
On the other hand, the actual volume V ₀ (mm ³ ) of the film of this unit area is the specific weight ρ (g / mm ³ ) of the resin composition constituting the film and the actual weight of the film per unit area (1 m ² ). It is calculated by applying W (g) to the following formula (4).
V ₀ (mm ³ ) = W / ρ (4)
The total volume V _H (mm ³ ) of the recesses per unit area of the film is obtained by subtracting the “actual volume V ₀ ” from the “film apparent volume V _A ” as shown in the following formula (5). Calculated.
V _H (mm ³ ) = V _A −V ₀ = V _A − (W / ρ) (5)
Therefore, the porosity (%) can be obtained as follows.
Porosity P (%) = V _H / V _A × 100
= (V _A- (W / ρ)) / V _A × 100
= 1−W / (ρ · V _A ) × 100
= 1−W / (ρ · t _max · 10 ⁶ ) × 100

The porosity (%) can be obtained by the above formula, but can also be obtained by taking an image of a cross-section or a concave surface of an actual film with a microscope and performing image processing.

Here, the maximum thickness t _max of the film indicates the distance (in the thickness direction of the film) from one upper surface to the other surface when a concave portion is formed on one surface of the film. When a concave portion is formed on the surface, the distance (in the film thickness direction) from one upper surface to the other upper surface is shown.

The maximum thickness t _max of the film 10 is preferably 0.01 mm to 2 mm, more preferably 0.1 to 1 mm, and further preferably 0.3 to 0.8 mm. When the maximum thickness t _max of the solar cell sealing film is within this range, damage to the front surface side transparent protective member, the solar cell, the back surface side protective member, etc. in the laminating step can be suppressed, and the solar cell can be obtained even at a relatively low temperature. This is preferable because the module can be laminated. Moreover, the film 10 can ensure sufficient light transmittance, and the solar cell module using the film 10 has a high photovoltaic power generation amount.

The film 10 can be manufactured by molding a thermoplastic resin composition. The thermoplastic resin composition is not particularly limited, but preferably has high transparency. The thermoplastic resin composition includes a thermoplastic resin, and further includes a crosslinking agent, a crosslinking accelerator, a coupling agent, a light stabilizer, an ultraviolet absorber, an antioxidant, and the like as necessary.

Examples of the thermoplastic resin include an ethylene / α-olefin copolymer composed of ethylene and an α-olefin having 3 to 20 carbon atoms, a high density ethylene resin, a low density ethylene resin, a medium density ethylene resin, and an ultra-low Density ethylene resin, propylene (co) polymer, 1-butene (co) polymer, 4-methylpentene-1 (co) polymer, ethylene / cyclic olefin copolymer, ethylene / α-olefin / cyclic olefin copolymer Polymer, ethylene / α-olefin / non-conjugated polyene copolymer, ethylene / α-olefin / conjugated polyene copolymer, ethylene / aromatic vinyl copolymer, ethylene / α-olefin / aromatic vinyl copolymer, etc. Olefin resin, ethylene / unsaturated carboxylic anhydride copolymer, ethylene / α-olefin / unsaturated carboxylic anhydride copolymer , Ethylene / epoxy-containing unsaturated compound copolymer, ethylene / α-olefin / epoxy-containing unsaturated compound copolymer, ethylene / vinyl acetate copolymer; ethylene / acrylic acid copolymer, ethylene / methacrylic acid copolymer Ethylene / unsaturated carboxylic acid copolymers such as copolymers, ethylene / ethyl acrylate copolymers, ethylene / unsaturated carboxylic acid ester copolymers such as ethylene / methacrylic acid methyl copolymer, unsaturated carboxylic acid esters ( (Co) polymers, (meth) acrylic acid ester (co) polymers, ethylene / acrylic acid metal salt copolymers, ionomer resins such as ethylene / methacrylic acid metal salt copolymers, urethane resins, silicone resins, Acrylic acid resin, methacrylic acid resin, cyclic olefin (co) polymer, α-olefin, aromatic vinyl Compounds, aromatic polyene copolymers, ethylene / α-olefin / aromatic vinyl compounds / aromatic polyene copolymers, ethylene / aromatic vinyl compounds / aromatic polyene copolymers, styrene resins, acrylonitrile / butadiene / Styrene copolymer, styrene / conjugated diene copolymer, acrylonitrile / styrene copolymer, acrylonitrile / ethylene / α-olefin / non-conjugated polyene / styrene copolymer, acrylonitrile / ethylene / α-olefin / conjugated polyene / styrene copolymer Polymer, methacrylic acid / styrene copolymer, ethylene terephthalate resin, fluororesin, polyester carbonate, polyvinyl chloride, polyvinylidene chloride, polyolefin-based thermoplastic elastomer, polystyrene-based thermoplastic elastomer, polyurethane-based heat Examples thereof include a plastic elastomer, a 1,2 polybutadiene-based thermoplastic elastomer, a trans polyisoprene-based thermoplastic elastomer, a chlorinated polyethylene-based thermoplastic elastomer, a liquid crystalline polyester, and polylactic acid.

Among these, an ethylene / α-olefin copolymer comprising ethylene and an α-olefin having 3 to 20 carbon atoms, a low density ethylene resin, a medium density ethylene resin, an ultra low density ethylene resin, propylene (co) heavy 1-butene (co) polymer, 4-methylpentene-1 (co) polymer, ethylene / cyclic olefin copolymer, ethylene / α-olefin / cyclic olefin copolymer, ethylene / α-olefin / non Conjugated polyene copolymers, ethylene / α-olefin / conjugated polyene copolymers, ethylene / aromatic vinyl copolymers, ethylene / α-olefin / aromatic vinyl copolymers and other olefin resins, ethylene / unsaturated anhydrous Carboxylic acid copolymers, ethylene / α-olefin / unsaturated carboxylic anhydride copolymers, ethylene / epoxy-containing unsaturated compounds Ethylene / α-olefin / epoxy-containing unsaturated compound copolymer, ethylene / acrylic acid copolymer, ethylene / unsaturated carboxylic acid copolymer such as ethylene / methacrylic acid copolymer, ethylene / ethyl acrylate Copolymers, unsaturated carboxylic acid ester (co) polymers, (meth) acrylic acid ester (co) polymers, ethylene / unsaturated carboxylic acid ester copolymers such as ethylene / methyl methacrylate copolymer, ethylene・ Ionomer resins such as acrylic acid metal salt copolymers, ethylene / methacrylic acid metal salt copolymers, cyclic olefin (co) polymers, α-olefins, aromatic vinyl compounds, aromatic polyene copolymers, ethylene α-olefin / aromatic vinyl compound / aromatic polyene copolymer, ethylene / aromatic vinyl compound / aromatic poly En copolymer, acrylonitrile / butadiene / styrene copolymer, styrene / conjugated diene copolymer, acrylonitrile / styrene copolymer, acrylonitrile / ethylene / α-olefin / non-conjugated polyene / styrene copolymer, acrylonitrile / ethylene / α-olefin / conjugated polyene / styrene copolymer and methacrylic acid / styrene copolymer are preferred.
Further, an ethylene / α-olefin copolymer composed of ethylene and an α-olefin having 3 to 20 carbon atoms is more preferable. The thermoplastic resin composition described above may be modified with a silane compound.

The ethylene / α-olefin copolymer preferably satisfies the following requirements a1) to a4).
a1) The content ratio of the structural unit derived from ethylene is 80 to 90 mol%, and the content ratio of the structural unit derived from the α-olefin having 3 to 20 carbon atoms is 10 to 20 mol%.
a2) Based on ASTM D1238, MFR measured under the conditions of 190 ° C. and 2.16 kg load is 0.5 to 50 g / 10 min.
a3) The density measured according to ASTM D1505 is 0.865 to 0.884 g / cm ³ .
a4) The Shore A hardness measured according to ASTM D2240 is 60 to 85.

Hereinafter, requirements a1) to a4) will be described.

(Requirement a1)
The proportion of structural units derived from α-olefins having 3 to 20 carbon atoms (hereinafter also referred to as “α-olefin units”) contained in the ethylene / α-olefin copolymer is transparent, flexible, and manufactured. From the viewpoint of balance of efficiency, 10 to 20 mol% is preferable, 12 to 20 mol% is more preferable, and 13 to 18 mol% is still more preferable.

The ethylene / α-olefin copolymer may contain a non-conjugated polyene. As the non-conjugated polyene, a compound having two or more non-conjugated unsaturated bonds can be used without limitation. Specifically, as the non-conjugated polyene, either a non-conjugated cyclic polyene or a non-conjugated chain polyene can be used, and a non-conjugated cyclic polyene and a non-conjugated chain polyene can also be used in combination. The non-conjugated polyene includes a non-conjugated polyene in which only one carbon / carbon double bond that can be polymerized with a catalyst exists in one molecule, and a carbon / carbon double bond. Of these, any non-conjugated polyene having two carbon / carbon double bonds that can be polymerized with the catalyst may be used. Among these, the non-conjugated polyene in which only one polymerizable carbon / carbon double bond is present in one molecule does not include a chain polyene in which both ends are vinyl groups (CH ₂ ═CH—). When there are two or more carbon / carbon double bonds in such a non-conjugated polyene, only one carbon / carbon double bond is present as a vinyl group at the molecular end, and other carbon / carbon double bonds are present. The double bond (C = C) is preferably present in the form of an internal olefin structure in the molecular chain (including the main chain and the side chain). The concept of non-conjugated cyclic polyene and non-conjugated chain polyene includes the above-described non-conjugated polyene having only one polymerizable carbon / carbon double bond in one molecule, and carbon / carbon double bond. Of these, non-conjugated polyenes in which two carbon / carbon double bonds that can be polymerized with the catalyst exist in one molecule are also included. The conjugated chain polyene also includes conjugated triene or tetraene.

Specific examples of the non-conjugated polyene include compounds described in paragraphs 0061 to 0084 of WO 2005/105867 pamphlet and paragraphs 0026 to 0035 of JP 2008-308696 A.

In particular, as non-conjugated polyene having only one polymerizable carbon / carbon double bond in one molecule, an alicyclic moiety having one carbon / carbon double bond (unsaturated bond), an alkylidene group, etc. And a chain portion having an internal olefin bond (carbon / carbon double bond) that is not polymerized or poorly polymerized by the metallocene catalyst. Specific examples include 5-ethylidene-2-norbornene (ENB), 5-propylidene-2-norbornene, and 5-butylidene-2-norbornene. Specific examples of the non-conjugated polyene having two polymerizable carbon / carbon double bonds in one molecule among the carbon / carbon double bonds include 5-vinyl-2-norbornene (VNB), 5-alkenyl-2-norbornene such as 5-allyl-2-norbornene; 2,5-norbornadiene, dicyclopentadiene (DCPD), tetracyclo [4.4.0.1 ^2,5 . Alicyclic polyenes such as 1 ^7,10 ] dodeca-3,8-diene; α, ω-dienes such as 1,7-octadiene and 1,9-decadiene.

In the case of an ethylene / α-olefin / non-conjugated polyene copolymer, the proportion of structural units derived from non-conjugated polyene (hereinafter also referred to as “non-conjugated polyene units”) is 0.01 to 5.0 mol%. The amount is preferably 0.01 to 4.5 mol%, more preferably 0.05 to 4.0 mol%. When the content ratio of the non-conjugated polyene unit is 0.01 mol% or more, the crosslinking property is excellent. On the other hand, it can suppress that a gel-like foreign material generate | occur | produces in the film as the content rate of a nonconjugated polyene unit is 5.0 mol% or less.

(Requirement a2)
According to ASTM D1238, the melt flow rate (MFR) of ethylene / α-olefin copolymer measured under the conditions of 190 ° C. and 2.16 kg load is the production efficiency, insulation resistance, moisture permeability, glass, etc. From the viewpoint of the balance between adhesion and heat resistance, it is preferably 0.5 to 50 g / 10 minutes, more preferably 10 to 45 g / 10 minutes, and further preferably 10 to 40 g / 10 minutes. preferable. The MFR of the ethylene / α-olefin copolymer is adjusted by adjusting the polymerization temperature, the polymerization pressure, the molar ratio of the ethylene and α-olefin monomer concentrations and the hydrogen concentration in the polymerization system, and the like. Can be adjusted.

(Requirement a3)
The density of the ethylene / α-olefin copolymer measured according to ASTM D1505 is 0.865 to 0.884 g / cm ³ from the viewpoint of balance of transparency, production efficiency, flexibility, and heat resistance. It is preferably 0.865 to 0.880 g / cm ³ . The density of the ethylene / α-olefin copolymer can be adjusted by a balance between the content ratio of ethylene units and the content ratio of α-olefin units. That is, when the content ratio of the ethylene unit is increased, the crystallinity is increased and a high-density ethylene / α-olefin copolymer can be obtained. On the other hand, when the content ratio of the ethylene unit is lowered, the crystallinity is lowered and an ethylene / α-olefin copolymer having a low density can be obtained.

(Requirement a4)
The Shore A hardness of the ethylene / α-olefin copolymer, measured according to ASTM D2240, is preferably 60 to 85 from the viewpoint of balance between production efficiency, heat resistance, transparency, and flexibility. 60 to 83 is more preferable, and 65 to 80 is still more preferable. The Shore A hardness of the ethylene / α-olefin copolymer can be adjusted by controlling the content and density of the ethylene unit in the ethylene / α-olefin copolymer. That is, an ethylene / α-olefin copolymer having a high ethylene unit content and high density has a high Shore A hardness. On the other hand, an ethylene / α-olefin copolymer having a low content of ethylene units and a low density has a low Shore A hardness.

A film made of a thermoplastic resin composition containing an ethylene / α-olefin copolymer satisfying the above requirements a1) to a4) tends to cause blocking and air remaining, but is effectively improved by the present invention.

As the film containing the ethylene / α-olefin copolymer as described above, those described in International Publication No. 2012/60086 and International Publication No. 2012/046456 can be used.

(Ethylene resin composition)
A film for encapsulating a solar cell according to this embodiment comprises 100 parts by weight of the aforementioned ethylene / α-olefin copolymer, 0.1 to 5 parts by weight of a silane coupling agent such as an ethylenically unsaturated silane compound, A preferred embodiment is composed of an ethylene-based resin composition containing 0.1 to 3 parts by weight of a crosslinking agent such as an oxide.

Further, the ethylene-based resin composition contains 0.1 to 4 parts by weight of an ethylenically unsaturated silane compound and 0.2 to 3 parts of an organic peroxide with respect to 100 parts by weight of the ethylene / α-olefin copolymer. It is preferably contained in an amount of 0.1 to 3 parts by weight of the ethylenically unsaturated silane compound and 0.2 to 2.5 parts of the organic peroxide with respect to 100 parts by weight of the ethylene / α-olefin copolymer. It is particularly preferable to contain parts by weight.

(Ethylenically unsaturated silane compound)
Adhesiveness can be improved as an ethylenically unsaturated silane compound is 0.1 weight part or more. On the other hand, when the ethylenically unsaturated silane compound is 4 parts by weight or less, the balance between cost and performance of the solar cell sealing film can be improved, and the ethylenically unsaturated silane compound can be used in the solar cell module. It is possible to reduce the amount of organic peroxide added to cause graft reaction to the ethylene / α-olefin copolymer during lamination. For this reason, the gelatinization at the time of obtaining the film for solar cell sealing into a film form with an extruder can be suppressed. For this reason, since the torque of an extruder falls, film shaping | molding can be made easy. Moreover, since generation | occurrence | production of a gel thing can be suppressed in an extruder, generation | occurrence | production of the unnecessary unevenness | corrugation in the surface of a film can be suppressed, and the deterioration of an external appearance can be suppressed.

If there is a gel in the film, cracks will occur around the gel when a voltage is applied, and the dielectric breakdown voltage will decrease, but the content of the ethylenically unsaturated silane compound should be 4 parts by weight or less. Thus, a decrease in dielectric breakdown voltage can be suppressed. In addition, when there is a gel material inside the film, moisture permeation easily occurs at the gel material interface. However, by making the content of the ethylenically unsaturated silane compound 4 parts by weight or less, it is possible to suppress a decrease in moisture permeability. .

A conventionally well-known thing can be used for an ethylenically unsaturated silane compound, and there is no restriction | limiting in particular. Specifically, vinyltriethoxysilane, vinyltrimethoxysilane, vinyltris (β-methoxyethoxysilane), γ-glycidoxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane Etc. can be used. Preferred are γ-glycidoxypropylmethoxysilane, γ-aminopropyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, and vinyltriethoxysilane, which have good adhesion.

(Organic peroxide)
The organic peroxide is used as a radical initiator for graft modification of an ethylenically unsaturated silane compound and an ethylene / α-olefin copolymer, and further, an ethylene / α-olefin copolymer solar cell module laminate. Used as a radical initiator in the crosslinking reaction during molding. By graft-modifying an ethylenically unsaturated silane compound to the ethylene / α-olefin copolymer, a solar cell module having good adhesion to the surface side transparent protective member, solar cell, back side protective member, etc. is obtained. It is done. Further, by crosslinking the ethylene / α-olefin copolymer, a solar cell module having excellent heat resistance and adhesiveness can be obtained.

The organic peroxide preferably used is one that can graft-modify an ethylenically unsaturated silane compound to the ethylene / α-olefin copolymer or crosslink the ethylene / α-olefin copolymer. However, the one-minute half-life temperature of the organic peroxide is 100 to 170 ° C. from the balance between the productivity in extrusion film forming and the crosslinking rate in the lamination of the solar cell module. When the one-minute half-life temperature of the organic peroxide is 100 ° C. or higher, it is possible to prevent the gel from being generated on the solar cell sealing film obtained from the resin composition during extrusion film molding, and the torque of the extruder Decreases, film formation can be facilitated. Moreover, since generation | occurrence | production of a gel thing can be suppressed in an extruder, generation | occurrence | production of the unnecessary unevenness | corrugation in the surface of a film can be suppressed, and the deterioration of an external appearance can be suppressed.

If there is a gel in the film, a crack will occur around the gel when a voltage is applied, and the dielectric breakdown voltage will decrease, but the half-life temperature of the organic peroxide will be 100 ° C or higher. Thus, a decrease in dielectric breakdown voltage can be suppressed. In addition, if there is a gel material inside the film, moisture permeation easily occurs at the gel material interface. However, by reducing the one-minute half-life temperature of the organic peroxide to 100 ° C. or higher, it is possible to suppress a decrease in moisture permeability. .

On the other hand, when the one-minute half-life temperature of the organic peroxide is 170 ° C. or lower, it is possible to suppress a decrease in the crosslinking rate during the lamination molding of the solar cell module, and thus it is possible to prevent a decrease in the productivity of the solar cell module. . Moreover, the heat resistance of a solar cell sealing film and the fall of adhesiveness can also be prevented.

Known organic peroxides can be used. Preferred examples of the organic peroxide having a 1 minute half-life temperature in the range of 100 to 170 ° C. include dilauroyl peroxide, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate Dibenzoyl peroxide, t-amylperoxy-2-ethylhexanoate, t-butylperoxy-2-ethylhexanoate, t-butylperoxyisobutyrate, t-butylperoxymaleic acid, 1 , 1-Di (t-amylperoxy) -3,3,5-trimethylcyclohexane, 1,1-di (t-amylperoxy) cyclohexane, t-amylperoxyisononanoate, t-amylperoxynormal Octoate, 1,1-di (t-butylperoxy) -3,3,5-trimethylcyclohexane, 1,1-di ( -Butylperoxy) cyclohexane, t-butylperoxyisopropyl carbonate, t-butylperoxy-2-ethylhexyl carbonate, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, t-amyl-peroxy Examples include benzoate, t-butyl peroxyacetate, t-butyl peroxyisononanoate, 2,2-di (t-butylperoxy) butane, t-butyl peroxybenzoate, and the like. Preferably, dilauroyl peroxide, t-butyl peroxyisopropyl carbonate, t-butyl peroxyacetate, t-butyl peroxyisononanoate, t-butyl peroxy-2-ethylhexyl carbonate, t-butyl peroxybenzoate, etc. Is mentioned.

(UV absorber, light stabilizer, heat stabilizer)
The ethylene resin composition preferably contains at least one additive selected from the group consisting of ultraviolet absorbers, light stabilizers, and heat stabilizers. The amount of these additives is preferably 0.005 to 5 parts by weight with respect to 100 parts by weight of the ethylene / α-olefin copolymer. Furthermore, it is preferable to contain at least two kinds of additives selected from the above three kinds, and it is particularly preferred that all of the above three kinds are contained. When the blending amount of the above additive is within the above range, the effect of improving the resistance to high temperature and high humidity, heat cycle resistance, weather resistance stability, and heat stability is sufficiently secured, and for solar cell sealing Since transparency of a film and the adhesiveness fall with a surface side transparent protection member, a photovoltaic cell, a back surface side protection member, etc. can be prevented, it is preferable.

Specific examples of the ultraviolet absorber include 2-hydroxy-4-normal-octyloxybenzophenone, 2-hydroxy-4methoxybenzophenone, 2,2-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy- Benzophenones such as 4-carboxybenzophenone and 2-hydroxy-4-N-octoxybenzophenone; 2- (2-hydroxy-3,5-di-t-butylphenyl) benzotriazole, 2- (2-hydroxy-5 -Methylphenyl) benzotriazoles such as benzotriazole; salicylic acid esters such as phenylsalicylate and p-octylphenylsulcylate are used.

Examples of the light stabilizer include bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, poly [{6- (1,1,3,3-tetramethylbutyl) amino-1,3, 5-triazine-2,4-diyl} {(2,2,6,6-tetramethyl-4-piperidyl) imino} hexamethylene {(2,2,6,6-tetramethyl-4-piperidyl) imino} Hindered amine compounds such as hindered piperidine compounds and the like are preferably used.

Specific examples of heat-resistant stabilizers include tris (2,4-di-tert-butylphenyl) phosphite, bis [2,4-bis (1,1-dimethylethyl) -6-methylphenyl] ethyl ester. Phosphorous acid, tetrakis (2,4-di-tert-butylphenyl) [1,1-biphenyl] -4,4′-diylbisphosphonite, and bis (2,4-di-tert-butylphenyl) Phosphite heat stabilizers such as pentaerythritol diphosphite; lactone heat stabilizers such as the reaction product of 3-hydroxy-5,7-di-tert-butyl-furan-2-one and o-xylene; 3,3 ′, 3 ″, 5,5 ′, 5 ″ -hexa-tert-butyl-a, a ′, a ″-(methylene-2,4,6-triyl) tri-p-cresol, 1,3 , 5-trime Tyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxyphenyl) benzylbenzene, pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) Propionate], octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, thiodiethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], etc. Hindered phenol heat stabilizers, sulfur heat stabilizers, amine heat stabilizers, etc. In addition, these can be used alone or in combination of two or more. A heat resistant stabilizer and a hindered phenol heat stabilizer are preferable.

(Other additives)
Various components other than the components detailed above can be appropriately contained in the ethylene resin composition constituting the solar cell sealing film as long as the object of the present invention is not impaired. Examples include various polyolefins other than ethylene / α-olefin copolymers, styrene-based, ethylene-based block copolymers, and propylene-based polymers. These may be contained in an amount of 0.0001 to 50 parts by weight, preferably 0.001 to 40 parts by weight, based on 100 parts by weight of the ethylene / α-olefin copolymer. One kind selected from various resins other than polyolefin, and / or various rubbers, plasticizers, fillers, pigments, dyes, antistatic agents, antibacterial agents, antifungal agents, flame retardants, crosslinking aids, and dispersing agents. The above additives can be appropriately contained.

In particular, when a crosslinking aid is contained, the amount of crosslinking aid is 0.05 to 5 parts by weight with respect to 100 parts by weight of the ethylene / α-olefin copolymer. It is preferable because it can have heat resistance, mechanical properties, and adhesiveness.

As the crosslinking aid, conventionally known ones generally used for olefinic resins can be used. Such a crosslinking aid is a compound having two or more double bonds in the molecule. Specifically, monoacrylates such as t-butyl acrylate, lauryl acrylate, cetyl acrylate, stearyl acrylate, 2-methoxyethyl acrylate, ethyl carbitol acrylate, methoxytripropylene glycol acrylate; t-butyl methacrylate, lauryl methacrylate, cetyl methacrylate Monomethacrylate such as stearyl methacrylate, methoxyethylene glycol methacrylate, methoxypolyethylene glycol methacrylate; 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, 1,9-nonanediol diacrylate, neopentyl glycol diacrylate , Diethylene glycol diacrylate, tetraethylene glycol diacrylate Diacrylates such as polyethylene glycol diacrylate, tripropylene glycol diacrylate, polypropylene glycol diacrylate; 1,3-butanediol dimethacrylate, 1,6-hexanediol dimethacrylate, 1,9-nonanediol dimethacrylate neo Dimethacrylates such as pentyl glycol dimethacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate; triacrylates such as trimethylolpropane triacrylate, tetramethylolmethane triacrylate, pentaerythritol triacrylate; Trimethylolpropane trimethacrylate Trimethacrylates such as methylolethane trimethacrylate; Tetraacrylates such as pentaerythritol tetraacrylate and tetramethylolmethane tetraacrylate; Divinyl aromatic compounds such as divinylbenzene and di-i-propenylbenzene; Triallyl cyanurate and triallyl isocyanurate A diallyl compound such as diallyl phthalate; a triallyl compound: p-quinonedioxime, an oxime such as pp′-dibenzoylquinonedioxime, and a maleimide such as phenylmaleimide. Among these crosslinking aids, more preferred are triacrylates such as diacrylate, dimethacrylate, divinyl aromatic compound, trimethylolpropane triacrylate, tetramethylolmethane triacrylate, pentaerythritol triacrylate; trimethylolpropane trimethacrylate , Trimethacrylates such as trimethylolethane trimethacrylate; tetraacrylates such as pentaerythritol tetraacrylate and tetramethylolmethane tetraacrylate; cyanurates such as triallyl cyanurate and triallyl isocyanurate; diallyl compounds such as diallyl phthalate; triallyl compound: p -Oximes such as quinonedioxime and pp'-dibenzoylquinonedioxime: phenylmaleimi And maleimides. Further, among these, triallyl isocyanurate is particularly preferable, and the balance between the generation of bubbles and the crosslinking property of the solar cell sealing film after lamination is most excellent.

Here, the tensile elastic modulus at 23 ° C. of the film 10 is preferably 6 to 13 MPa. The tensile elastic modulus is measured as follows, for example. First, a 1 mm thick film having the same composition as the film 10 is prepared. Then, the film is punched with a dumbbell according to JIS K7113, and measured with an autograph (manufactured by Shimadzu Corporation: AGS-J) at a chuck interval of 40 mm and a tensile speed of 1 mm / min. At this time, the temperature of the measurement environment is 23 ° C. and the humidity is 50% Rh.

In the film 10 having the tensile modulus as described above, blocking and air remaining are likely to occur, but this is effectively improved by the present invention.

As a method for producing the film 10 according to the present embodiment, a commonly used method can be used, but it is preferably produced by melt blending using a kneader, a Banbury mixer, an extruder, or the like. In particular, the production with an extruder capable of continuous production is preferred.

Although there is no restriction | limiting in particular in the shaping | molding method of the film 10 for solar cell sealing, It is possible to employ | adopt well-known various shaping | molding methods (Cast shaping | molding, extrusion film shaping | molding, inflation molding, injection molding, compression molding, etc.). . In particular, it is the most preferred embodiment to obtain a solar cell sealing film as follows. That is, for example, blending by hand in a bag such as a plastic bag, or using an agitator / mixer such as a Henschel mixer, tumbler, or super mixer, ethylene / α-olefin copolymer, ethylenically unsaturated silane compound, organic A composition is obtained by blending a peroxide, an ultraviolet absorber, a light stabilizer, a heat stabilizer, and other additives as required. And the obtained composition is thrown into the extrusion film molding hopper, extrusion film molding is performed while melt-kneading, and a solar cell sealing film is obtained. As the extrusion temperature range, the extrusion temperature is 100 to 130 ° C. When the extrusion temperature is 100 ° C. or higher, the productivity of the solar cell sealing film can be improved. When the extrusion temperature is 130 ° C. or lower, gelation hardly occurs when the ethylene resin composition used for the solar cell sealing film is formed into a film by an extruder to obtain a solar cell sealing film. Therefore, the torque of the extruder can be prevented from increasing, and film formation can be facilitated. Moreover, since it becomes difficult to generate unnecessary unevenness on the surface of the sheet, it is possible to prevent deterioration of the appearance. Moreover, since generation | occurrence | production of the crack in a film inside can be suppressed when a voltage is applied, the fall of a dielectric breakdown voltage can be prevented. Furthermore, a decrease in moisture permeability can also be suppressed.

Furthermore, the film 10 can be used in a sheet type cut according to the size of the solar cell module, or a roll type that can be cut according to the size immediately before producing the solar cell module.

The film 10 may include a hard coat layer for protecting the front surface or the back surface, an adhesive layer, an antireflection layer, a gas barrier layer, an antifouling layer, and the like. If classified by material, layer made of UV curable resin, layer made of thermosetting resin, layer made of polyolefin resin, layer made of carboxylic acid modified polyolefin resin, layer made of fluorine-containing resin, cyclic olefin (co) Examples thereof include a layer made of a polymer and a layer made of an inorganic compound.

The film 10 having a recess formed on the surface can be produced by embossing using an embossing roll having a specific shape. For example, the embossing roll can be prepared by forming, on the surface of a metal roll, a convex part pattern designed according to the concave part desired to be formed on the film by metal processing according to the prior art. In such a case, by adjusting the size, shape, position, depth, etc. of the protrusions on the surface of the embossing roll, the shape, average depth, area ratio of the upper surface 110, period p, and the like are formed on the film roll 20. The angle r can be adjusted.

In the solar cell sealing film as described above, blocking between the film surfaces is suppressed, and a solar cell sealing film with high transport storage efficiency is obtained. Moreover, if the film for solar cell sealing as described above is used for manufacturing a solar cell module, the generation of bubbles due to air entrainment can be suppressed.

A method for producing a solar cell module using the film 10 according to this embodiment will be described below.
FIG. 6 is a schematic cross-sectional view illustrating the process of the method for manufacturing the solar cell module according to this embodiment.
The manufacturing method of the solar cell module according to the present embodiment includes a preparation process and a sealing process. In the preparation step, the solar cell sealing film 10 is prepared. In the sealing step, the front surface side transparent protective member 40, the first solar cell sealing film 120, the solar battery cell 30, the second solar cell sealing film 140, and the back surface side protective member 42 are laminated in this order. The laminate is formed, and the laminate is integrated by heating and pressing. This will be described in detail below.

The laminate includes, for example, the front surface side transparent protective member 40, the first solar cell sealing film 120, the solar battery cell 30, the second solar cell sealing film 140, and the back surface side protective member 42 in this order. Laminated.

The surface-side transparent protective member 40 is not particularly limited, but is located on the outermost layer of the solar cell module, and therefore has long-term reliability in outdoor exposure of the solar cell module including weather resistance, water repellency, contamination resistance, mechanical strength, and the like. It is preferable to have performance for ensuring the property. Moreover, in order to utilize sunlight effectively, it is preferable that it is a highly transparent sheet | seat with a small optical loss.

As the material of the surface side transparent protective member 40, a resin film or glass substrate made of polyester resin such as polyethylene terephthalate (PET), fluorine resin, acrylic resin, cyclic olefin (co) polymer, ethylene-vinyl acetate copolymer, etc. Etc. When a glass substrate is used, the glass substrate preferably has a total light transmittance of light having a wavelength of 350 to 1400 nm of 80% or more, and more preferably 90% or more. As such a glass substrate, it is common to use white plate glass with little absorption in the infrared region, but even blue plate glass has little influence on the output characteristics of the solar cell module as long as the thickness is 3 mm or less. . Further, tempered glass can be obtained by heat treatment to increase the mechanical strength of the glass substrate, but float plate glass without heat treatment may be used. Further, an antireflection coating may be provided on the light receiving surface side of the glass substrate in order to suppress reflection.

Although the back surface side protection member 42 is not particularly limited, since it is located on the outermost layer of the solar cell module, various characteristics such as weather resistance and mechanical strength are required in the same manner as the above surface side transparent protection member 40. Therefore, the back surface side protection member 42 may be made of the same material as the front surface side transparent protection member 40. That is, the above-described various materials used as the front surface side transparent protective member 40 can also be used as the back surface side protective member 42. In particular, a polyester resin and glass can be preferably used. Moreover, since the back surface side protection member 42 does not presuppose passage of sunlight, the transparency calculated | required by the surface side transparent protection member 40 is not necessarily requested | required. Therefore, a reinforcing plate may be attached to increase the mechanical strength of the solar cell module or to prevent distortion and warpage due to temperature change. As the reinforcing plate, for example, a steel plate, a plastic plate, an FRP (glass fiber reinforced plastic) plate or the like can be preferably used.

A plurality of recesses 100 are arranged in a grid pattern on at least one surface of the first solar cell sealing film 120 and the second solar cell sealing film 140. The average depth of the plurality of recesses 100 is 50 μm or more and 200 μm or less, and the area ratio of the upper surface 110 is 10% or less. The first solar cell sealing film 120 and the second solar cell sealing film 140 may be the same film or may be different from each other. That is, at least one of the shape and arrangement of the recesses 100, the average depth of the recesses 100, the area ratio of the upper surface 110, the period p, the angle r, the resin composition, and the like may be different from each other.

In the sealing step, the front surface side transparent protective member 40, the first solar cell sealing film 120, the solar battery cell 30, the second solar cell sealing film 140, and the back surface side protective member 42 are laminated in this order. The laminate is formed, and the laminate is integrated by heating and pressing. By heating and pressurizing in this step, the resin constituting the film 10 flows and the concave portion 100 of the film 10 is lost.

In the laminated body in the sealing step, the direction of the film is not particularly limited, but the surface 120A on which the concave portion 100 of the first solar cell sealing film 120 is formed, and the second solar cell sealing film 140. It is preferable that the laminated body is formed by laminating so that the surface 140 </ b> A on which the concave portion 100 is formed faces the solar battery cell 30. Alternatively, the stacked body may be formed by stacking so that the surface having the concave portion is in contact with the solar battery cell 30. By doing in this way, at the time of the process which heats and pressurizes a laminated body and integrates, the function as a cushion can be fulfill | performed by crushing a recessed part, and the pressing force added to a photovoltaic cell can be reduced. As a result, damage to the solar battery cell can be suppressed.

In addition, when the laminate is heated and pressurized to be integrated, the concave portion forms a passage for air, and the deaeration performance is improved. For this reason, poor deaeration is suppressed.

Furthermore, since the heated and flowable resin can flow into the recess during the process of heating and pressurizing and integrating the laminate, there is an inconvenience that such resin protrudes outside the laminate. Can be suppressed.

In the step of integrating the laminate in the sealing step, the first solar cell sealing film 120 and the second solar cell sealing film 140 that have become flowable by heating protrude from the laminate. It is preferable to apply pressure and heat under such conditions.

Further, in the step of integrating the laminate in the sealing step, the laminate may be pressurized in a state where the laminate is placed on the hot plate 50.

In the step of integrating the laminate in the sealing step, the laminate may be pressurized by atmospheric pressure.

Further, in the step of integrating the laminate in the sealing step, the laminate may be surrounded by the soft sheet 60 and the hot plate 50, and the inside may be depressurized and pressurized by applying atmospheric pressure to the laminate.

For example, as shown in FIG. 6, from the top, the back surface side protection member 42, the second solar cell sealing film 140, the solar cell 30, the first solar cell sealing film 120, and the front surface side transparent protective member 40. Are stacked in this order on the hot plate 50.

One or more solar cells 30 can be included in the stacked body. In the example shown in figure, the several photovoltaic cell 30 is contained in the laminated body. And the some photovoltaic cell 30 is connected in series using the electrode which is not shown in figure. Here, the configuration and material of the electrode are not particularly limited, but in a specific example, the electrode has a laminated structure of a transparent conductive film and a metal film. The transparent conductive film is made of SnO ₂ , ITO, ZnO or the like. The metal film is made of a metal such as silver, gold, copper, tin, aluminum, cadmium, zinc, mercury, chromium, molybdenum, tungsten, nickel, and vanadium. These metal films may be used alone or as a composite alloy. The transparent conductive film and the metal film are formed by a method such as CVD, sputtering, or vapor deposition.

The first solar cell sealing film 120 and the second solar cell sealing film 140 may be separated from each other, but the first solar cell sealing film is formed by one film 10. 120 and the 2nd solar cell sealing film 140 may be comprised. For example, by folding a single film so as to enclose the solar battery cell 30, the solar battery cell 30 as shown in the figure is turned into the first solar battery sealing film 120 and the second solar battery sealing film 140. You may implement | achieve the state pinched | interposed by.

After the laminate as described above is covered with the soft sheet 60 as shown in the figure, the internal space surrounded by the soft sheet 60 and the hot plate 50 is decompressed. As a result, the laminate can be pressurized by atmospheric pressure. At this time, the hot plate 50 is heated to a predetermined temperature, and the first solar cell sealing film 120 and the second solar cell sealing film 140 are also heated by the heat.

As an example of the conditions at this time, the hot plate temperature is 70 ° C. or more and 170 ° C. or less, the vacuum time is 1 minute or more and 10 minutes or less, the press pressure is 0.1 atmosphere or more and 1 atmosphere or less, and the pressurization time is 1 minute or more and 20 minutes or less. It is.

In addition, the solar cell module is not limited to the above configuration, and layers other than the above can be appropriately provided as long as the object of the present invention is not impaired. Examples of the layer other than the above include an adhesive layer, a shock absorbing layer, a coating layer, an antireflection layer, a back surface rereflection layer, and a light diffusion layer. These layers are not particularly limited, but can be provided at appropriate positions in consideration of the purpose and characteristics of each layer.

As described above, according to the method for manufacturing a solar cell module using the solar cell sealing film according to the present embodiment, cracking of the solar cell, air entrainment due to poor deaeration at the time of sealing, resin to the end face of the laminate Problems such as protrusion of the composition can be solved.

Next, the operation and effect of this embodiment will be described.
In the solar cell sealing film according to the present embodiment, the film surfaces are less likely to be blocked when transported and stored, and the air release property in the production of the solar cell module is excellent.

It should be noted that the present invention is not limited to the above-described embodiment, and modifications, improvements, etc. within the scope that can achieve the object of the present invention are included in the present invention.

Hereinafter, the present invention will be specifically described with reference to examples. In addition, this embodiment is not limited to description of these Examples at all.

(Example 1)
[Synthesis of ethylene / α-olefin copolymer]
At one supply port of a 50 L internal polymerization vessel equipped with a stirring blade, 8.0 mmol / hr of a toluene solution of methylaluminoxane as a cocatalyst and bis (1,3-dimethylcyclopentadienyl) zirconium as a main catalyst Supply dichlorinated hexane slurry at a rate of 0.025 mmol / hr and triisobutylaluminum hexane at a rate of 0.5 mmol / hr, so that the total amount of dehydrated and purified normal hexane used as the polymerization solvent and polymerization solvent is 20 L / hr. Was fed continuously with dehydrated and purified normal hexane. At the same time, ethylene is continuously supplied to another supply port at a rate of 3 kg / hr, 1-butene at 15 kg / hr, and hydrogen at a rate of 5 NL / hr, a polymerization temperature of 90 ° C., a total pressure of 3 MPaG, and a residence time of 1.0. Continuous solution polymerization was performed under conditions of time. The ethylene / α-olefin copolymer normal hexane / toluene mixed solution produced in the polymerization vessel is continuously discharged through a discharge port provided at the bottom of the polymerization vessel, and the ethylene / α-olefin copolymer solution is discharged. The jacket portion was led to a connecting pipe heated with 3 to 25 kg / cm ² steam so that the normal hexane / toluene mixed solution had a temperature of 150 to 190 ° C. Immediately before reaching the connecting pipe, a supply port for injecting methanol, which is a catalyst deactivator, is attached, and methanol is injected at a rate of about 0.75 L / hr. The mixture was merged into a combined normal hexane / toluene mixed solution. The normal hexane / toluene mixed solution of the ethylene / α-olefin copolymer kept at about 190 ° C. in the connection pipe with steam jacket is subjected to pressure provided at the end of the connection pipe so as to maintain about 4.3 MPaG. The liquid was continuously fed to the flash tank by adjusting the opening of the control valve. In the transfer to the flash tank, the solution temperature and the pressure adjustment valve opening are set so that the pressure in the flash tank is about 0.1 MPaG and the temperature of the vapor part in the flash tank is maintained at about 180 ° C. It was broken. Thereafter, the strand was cooled in a water tank through a single screw extruder set at a die temperature of 180 ° C., and the strand was cut with a pellet cutter to obtain an ethylene / α-olefin copolymer as pellets. The yield was 2.2 kg / hr.

[Evaluation of ethylene / α-olefin copolymer]
<Content ratio of ethylene unit and α-olefin unit>
A solution obtained by heating and dissolving 0.35 g of a sample in 2.0 ml of hexachlorobutadiene was filtered through a glass filter (G2), 0.5 ml of deuterated benzene was added, and the mixture was placed in an NMR tube having an inner diameter of 10 mm. Using a JNM GX-400 type NMR measuring apparatus manufactured by JEOL Ltd., ¹³ C-NMR measurement was performed at 120 ° C. The number of integration was 8000 times or more. From the obtained ¹³ C-NMR spectrum, the content ratio of ethylene units and the content ratio of α-olefin units in the copolymer were quantified. As a result, the content of the α-olefin unit in the ethylene / α-olefin copolymer of this example was 14 mol%.

[MFR]
Based on ASTM D1238, the MFR of the ethylene / α-olefin copolymer was measured under the conditions of 190 ° C. and 2.16 kg load. As a result, the MFR of the ethylene / α-olefin copolymer of this example was 20 g / 10 min.

[density]
The density of the ethylene / α-olefin copolymer was measured in accordance with ASTM D1505. As a result, the density of the ethylene / α-olefin copolymer of this example was 0.870 g / cm ³ .

[Shore A hardness]
The ethylene / α-olefin copolymer was pressurized at 190 ° C., heated for 4 minutes and at 10 MPa, and then pressure-cooled at 10 MPa to room temperature for 5 minutes to obtain a sheet having a thickness of 3 mm. Using the obtained sheet, the Shore A hardness of the ethylene / α-olefin copolymer was measured in accordance with ASTM D2240. As a result, the Shore A hardness of the ethylene / α-olefin copolymer of this example was 70.

[Manufacture of solar cell sealing film]
With respect to 100 parts by weight of the obtained ethylene / α-olefin copolymer, 0.5 part by weight of γ-methacryloxypropyltrimethoxysilane as an ethylenically unsaturated silane compound and a half-life temperature of 1 minute as an organic peroxide 1.0 parts by weight of t-butylperoxy-2-ethylhexyl carbonate at 166 ° C., 1.2 parts by weight of triallyl isocyanurate as a crosslinking aid, and 2-hydroxy-4-normal-octyloxybenzophenone as an ultraviolet absorber 0.4 parts by weight, 0.2 parts by weight of bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate as a radical scavenger (light stabilizer), and Tris ( 2,4-di-tert-butylphenyl) phosphite 0.1 parts by weight, octadecyl-3- (3,5 as heat stabilizer 2 -Di-tert-butyl-4-hydroxyphenyl) propionate (0.1 part by weight) was blended to obtain a resin composition A.

A coat hanger type T die (lip shape: 270 × 0.8 mm) is attached to a single screw extruder (screw diameter: 20 mmφ, L / D = 28) manufactured by Thermo Plastic, and the die temperature is 100 ° C. Molding was performed using an embossing roll as the first cooling roll at a roll temperature of 30 ° C. and a winding speed of 1.0 m / min to obtain an embossed film (film for solar cell sealing) having a thickness of 500 μm. In addition, the convex pattern which has two or more square convex parts by planar view was uniformly formed in the whole on the surface of the embossing roll used in the present Example.

(Examples 2 to 7, 9 and Comparative Examples 1 to 3)
A solar cell sealing film was obtained in the same manner as in Example 1 except that an embossing roll having a convex pattern different from that in Example 1 was used. In any of the examples and comparative examples, a convex pattern having a plurality of convex portions was uniformly formed on the entire surface of the embossing roll used.

(Example 8)
A solar cell sealing film was obtained in the same manner as in Example 1 except that an ethylene / vinyl acetate copolymer (VA 28%, MFR 15 g / 10 min) was used as the resin composition B instead of the resin composition A.

[Evaluation of solar cell sealing film]
The following evaluation was performed about the film for solar cell sealing obtained in each Example and each comparative example, and the result was put together in Table 1.

<Recessed shape>
The shape of the concave portion of the solar cell sealing film was observed with an optical microscope. As a result, in Examples 1 to 5, 7, 8, and 9 and Comparative Examples 1 to 3, a plurality of square recesses were formed in a square lattice pattern as shown in FIG. In Example 6, as shown in FIG. 3, a plurality of equilateral triangular recesses were arranged in a triangular lattice pattern.

<Average depth of recess>
The average depth of the concave portion of the solar cell sealing film was measured. Specifically, 20 mm × 20 mm square film pieces are cut out at the center of the roll and at three locations 10 cm inside from both ends in the width direction of the roll, and the depth of each recess in these film pieces is set to one film piece. The average depth was determined by measuring 10 pieces per section by cross-sectional observation with an electron microscope. In each example and each comparative example, an emboss roll in which a convex pattern is uniformly formed on the whole is used, and thus the average value obtained in this way can be regarded as the average of the whole.

<Angle between top surface and recess>
The angle between the upper surface of the solar cell sealing film and the recess was measured. Specifically, in three places similar to the evaluation of the average depth of the concave portions, square film pieces of 20 mm × 20 mm are cut out, and the angle between each concave portion and the upper surface of these film pieces is 10 per film piece. Each was measured by cross-sectional observation with an electron microscope. The measured angles were almost uniform and were in the range of 45 ± 1 ° in Examples 1-6, 8, 9 and Comparative Examples 1-3. The angle was in the range of 25 ± 1 ° in Example 7. For convenience, Table 1 shows median values.

<Area ratio of top surface>
The area ratio of the upper surface was measured. Specifically, 10 mm × 10 mm square film pieces were cut out from the same three places as in the evaluation of the average depth, the surface shape of these film pieces was measured with an optical microscope, and the area ratio of the upper surface was calculated. The average value of two film pieces was determined as the area ratio of the upper surface of the film. In each example and each comparative example, an embossing roll in which a convex pattern is uniformly formed on the whole is used. Therefore, the area ratio obtained in this way can be regarded as the area ratio of the upper surface in the entire film.

<Cycle>
The period p of the array of recesses was measured. Specifically, 5 mm × 5 mm square film pieces were cut out from the same three places as in the evaluation of the average depth, and the surface shapes of these film pieces were measured with an optical microscope to measure the period. The period was substantially uniform, and in Example 1, it was in the range of 1030 ± 5 μm. For convenience, Table 1 shows median values. In all examples and comparative examples, the period was in the range of the median value ± 5 μm.

<Porosity>
The porosity P [%] of the solar cell sealing film was measured. Specifically, a 10 cm × 10 cm square film piece was cut out from the center of the roll, and the weight W [g] per unit area was measured from the total mass. Separately, the maximum film thickness t _max [mm] of the film and the specific gravity ρ [g / mm ³ ] of the film material were determined, and P (%) = 1−W / (ρ · t _max · 10 ⁶ ) × 100 From the relationship, the porosity P was determined. Here, the maximum film thickness _tmax was measured by cross-sectional observation similar to that performed in the evaluation of the average depth of the recesses. Moreover, specific gravity (rho) of film material was measured using the film obtained without performing embossing by the process similar to a present Example.

<Tensile modulus>
Moreover, the tensile elasticity modulus of the film for solar cell sealing was measured. A 1 mm thick film having the same composition as the solar cell sealing film was prepared. Then, the film was punched with a dumbbell according to JIS K7113, and measured with an autograph (manufactured by Shimadzu Corporation: AGS-J) at a chuck interval of 40 mm and a tensile speed of 1 mm / min. At this time, the temperature of the measurement environment was 23 ° C., and the humidity was 50% Rh. As a result, the tensile modulus was 8 MPa for the resin composition A used in Examples 1 to 7, 9 and Comparative Examples 1 to 3, and 15 MPa for the resin composition B used in Example 8.

<Blocking suppression performance>
When the obtained film roll for solar cell sealing having a width of 250 mm is left at 35 ° C. for 1 week and then the film is pulled out, the pulling strength is less than 1 kgf, and the case where the pulling strength is less than 1 kgf and less than 1.5 kgf is Δ The case of 1.5 kgf or more was evaluated as x.

[Manufacture of solar cell modules]
Using the obtained solar cell sealing film, a small module in which 18 cells were connected in series using a single crystal cell was prepared and evaluated. As the surface-side transparent protective member, heat-treated glass with embossing having a thickness of 3.2 mm made of white plate float glass manufactured by Asahi Glass Fabricate Co., Ltd. cut to 24 × 21 cm was used. A crystal cell (single crystal cell manufactured by Shinsung) was used which was cut into 5 × 3 cm with the bus bar silver electrode on the light receiving surface side as the center. The cells were connected in series in 18 cells using a copper ribbon electrode in which eutectic solder was coated on the copper foil. As a back sheet (back side protection member), a PET-based back sheet including silica-deposited PET was used. A part of the back sheet was cut with a cutter-knife into a part to be removed from the cell, and 18 cells were connected in series. The positive terminal and the negative terminal were taken out, and a solar cell sealing film was laminated using a vacuum laminator (NPC: LM-110x160-S) at a hot plate temperature of 150 ° C., a vacuum time of 4 minutes, and a pressurization time of 15 minutes. . After that, the solar cell sealing film protruding from the glass, the back sheet was cut, the edge sealing material was applied to the glass edge, the aluminum frame was attached, and then the terminal part cut out from the back sheet was RTV silicone was applied and cured.

[Evaluation of solar cell module]
<Air escape characteristics>
Observe through the glass of the obtained solar cell module, when bubbles are not confirmed by observation with an optical microscope, bubbles are confirmed by observation with an optical microscope, but bubbles are not confirmed by visual observation, which is a problem as product quality The case where there was no bubble was evaluated as Δ, and the case where bubbles were visually confirmed was evaluated as ×.

As shown in Table 1, in Examples 1 to 9, it was confirmed that both the blocking suppression performance and the air release property were excellent. On the other hand, in Comparative Example 1 in which the average depth of the recesses was smaller than 50 μm and Comparative Example 3 in which the area ratio of the upper surface was larger than 10%, the blocking suppression performance was inferior. Moreover, in the comparative example 2 with the average depth of a recessed part larger than 200 micrometers, it was inferior to air bleedability.

This application claims priority based on Japanese Patent Application No. 2015-020253 filed on Feb. 4, 2015, the entire disclosure of which is incorporated herein.

Claims

On at least one surface, a plurality of recesses are formed in a grid pattern,
The average depth of the plurality of recesses is 50 μm or more and 200 μm or less,
In at least one surface, when the apparent surface area of the case where the surface is to be flat and the S a, the area of the upper surface of the plurality of recesses are not formed S t, S t / S a × 100 (% The film for solar cell sealing whose area ratio of the said upper surface represented by this is 10% or less.
In the solar cell sealing film according to claim 1,
The film for solar cell sealing whose period of the arrangement | sequence of the said several recessed part is the range of 500 to 2000 micrometers.
In the solar cell sealing film according to claim 1 or 2,
The film for sealing a solar cell, wherein the upper surface and the surfaces constituting the plurality of recesses intersect at 30 ° or more and 60 ° or less.
In the solar cell sealing film according to any one of claims 1 to 3,
The plurality of recesses are square, rectangular, rhombus, parallelogram, triangle, or hexagon in plan view, and are filled with at least one surface at a certain distance from each other.
A film roll for sealing a solar cell, wherein the film for sealing a solar cell according to any one of claims 1 to 4 is wound around a core material.
A preparation step of preparing a film for sealing solar cells;
While laminating the surface side transparent protective member, the first solar cell sealing film, the solar battery cell, the second solar cell sealing film, and the back surface protective member in this order, to form a laminate, Sealing and integrating the laminate by heating and pressing,
In the first and second solar cell sealing films, a plurality of recesses are arranged in a lattice pattern on at least one surface,
The average depth of the plurality of recesses is 50 μm or more and 200 μm or less,
In at least one surface, when the apparent surface area of the case where the surface is to be flat and the S a, the area of the upper surface of the plurality of recesses are not formed S t, S t / S a × 100 (% The manufacturing method of the solar cell module whose area ratio of the said upper surface represented by this is 10% or less.