JP2016213401A - Composition for manufacturing sealant for solar batteries - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a good composition for manufacturing a sealant for solar batteries, which produces no acid and has satisfactory adhesiveness and which is superior in insulating property, and which is easy to control its temperature and achieves good processability.SOLUTION: A composition for manufacturing a sealant for solar batteries comprises: a resin mixture of an ethylene-α-olefin copolymer of which the melt flow rate (at 190°C with a load of 2.16 kg in conformity with JIS K7210) is 0.1-15 g/10 min, and an ethylene homopolymer of which the melt flow rate (at 190°C with a load of 2.16 kg in conformity with JIS K7210) is 50-100 g/10 min. In the resin mixture, the mass ratio of the ethylene-α-olefin copolymer to the ethylene homopolymer is 40/60 to 50/50.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a composition for producing a solar cell encapsulant used for encapsulating solar cell elements in a solar cell module, and a solar cell encapsulant produced using this composition. And a solar cell module using the same.

  In recent years, solar cell modules that directly convert sunlight into electrical energy have been widely used from the standpoints of effective use of resources and prevention of environmental pollution, and are being developed further in terms of durability and power generation efficiency. .

  As the structure of the solar cell module, for example, as shown in FIG. 1, a plurality of solar cell elements such as a surface side transparent protective member 11 made of a glass substrate or the like, a surface side solar cell encapsulant 13A, a silicon crystal cell, etc. 14, the back surface side solar cell sealing material 13B and the back surface side protection member (back cover) 12 are laminated in this order and bonded and integrated.

  As a sealing material used in such a solar cell module, a film of an ethylene-vinyl acetate copolymer (hereinafter also referred to as EVA) having excellent transparency and adhesiveness has been generally used. However, since EVA may generate acetic acid by hydrolysis and corrode the electrode of the solar cell module, in recent years, an ethylene / α-olefin copolymer that does not generate acetic acid is used as a material for a solar cell encapsulant. It attracts attention.

  Moreover, in order to improve the power generation efficiency of a solar cell module, the back side is used by using a back side sealing material to which an inorganic filler for coloring (titanium dioxide or the like) is added as the back side solar cell sealing material 13B. Light utilization efficiency by reflecting light incident between adjacent solar cell elements due to light reflection at the interface between the encapsulant and the front-side encapsulant or diffused reflection of light by the colorant and entering the solar cell element There is a known technique for enhancing the above (Patent Document 1).

JP 2014-139993 A

  In order to obtain a high electrical output of the solar cell module, the solar cell encapsulant is required to have high insulation so as not to cause current leakage. In particular, when an inorganic filler is added for coloring as described above, the insulating property may be lowered. Therefore, a countermeasure is required to prevent the insulating property from being lowered when an inorganic filler is added. It has been.

  Moreover, it is calculated | required that the sealing material for solar cells has sufficient adhesiveness with respect to a solar cell element, a surface side transparent protection member, and a back surface side protection member. And when manufacturing the sealing material for solar cells, it is calculated | required that the width | variety of the temperature which can be processed is wide for easy control of temperature.

  Accordingly, an object of the present invention is a composition for producing a solar cell encapsulant that does not generate acid, has excellent insulating properties, and has good adhesiveness, and is easy to control temperature and easy to process. It is in providing the favorable composition for solar cell sealing material manufacture.

  Moreover, the objective of this invention is providing the sealing material for solar cells manufactured by shape | molding this composition.

  Furthermore, the objective of this invention is providing the solar cell module manufactured by sealing a solar cell element with this solar cell sealing material.

  The above-mentioned purpose is an ethylene / α-olefin copolymer having a melt flow rate (conforming to JIS K7210, 190 ° C., load 2.16 kg) of 0.1 to 15 g / 10 min, a melt flow rate (conforming to JIS K7210, 190 ° C., load 2.16 kg) including a resin mixture with an ethylene homopolymer having a weight of 50 to 100 g / 10 min, and a mass ratio of the ethylene / α-olefin copolymer to the ethylene homopolymer in the resin mixture is 40 It is achieved by a composition for producing a sealing material for solar cells, which is / 60 to 50/50.

  According to the said structure, the range suitable for manufacturing the sealing material for solar cells in the wide temperature range by using the said 2 types of said polymer from which melt flow rate differs by the said mass ratio. In addition, it is possible to improve the insulating properties of the manufactured solar cell encapsulant and to obtain good adhesiveness. Since the ethylene / α-olefin copolymer and the ethylene homopolymer do not generate acid, they do not cause corrosion of the electrode of the solar cell module.

Preferred embodiments of the present invention are as follows.
(1) It further contains a nonmetallic inorganic filler. Even if an inorganic filler is included, a solar cell encapsulant with good insulation can be obtained.
(2) The inorganic filler is calcium carbonate and is contained in an amount of 5 to 50 parts by mass with respect to 100 parts by mass of the resin mixture. Even if an inorganic filler is included, a solar cell encapsulant with good insulation and adhesion can be obtained.
(3) The inorganic filler is kaolin and is contained in an amount of 0.1 to 5 parts by mass with respect to 100 parts by mass of the resin mixture. Even if an inorganic filler is included, a solar cell encapsulant with good insulation and adhesion can be obtained.
(4) The density of the ethylene homopolymer is 0.910 g / cm ³ or more and less than 0.930 g / cm ³ . A composition for producing a solar cell encapsulant that is further excellent in workability can be obtained.
(5) The ethylene / α-olefin copolymer is polymerized using a metallocene catalyst. A composition for producing a solar cell encapsulant that is further excellent in workability can be obtained.

  Moreover, the said objective has a solar cell sealing material formed by shape | molding the solar cell sealing material composition of this invention, a surface side protection member, a solar cell element, and a back surface side protection member, The said sun It is also achieved by a solar cell module in which the battery element is sealed with the solar cell sealing material of the present invention.

  According to the present invention, by using a specific ethylene / α-olefin copolymer and an ethylene homopolymer in a predetermined ratio, no acid is generated, the solar cell has excellent insulating properties and good adhesiveness. A composition for producing a solar cell encapsulant with good workability for producing an encapsulant for a solar cell is provided. Therefore, corrosion of the electrodes of the solar cell module due to acid does not occur, and a solar cell module having good power generation efficiency can be obtained.

It is a schematic sectional drawing of a common solar cell module.

  As described above, the composition for producing a solar cell sealing material of the present invention has an ethylene / α having a melt flow rate (based on JIS K7210, 190 ° C., load 2.16 kg) of 0.1 to 15 g / 10 min. A resin mixture of an olefin copolymer and an ethylene homopolymer having a melt flow rate (based on JIS K7210, 190 ° C., load 2.16 kg) of 50 to 100 g / 10 min is included. Hereinafter, the present invention will be described in detail.

(Ethylene / α-olefin copolymer)
The ethylene / α-olefin copolymer has a structural unit derived from ethylene as a main component, and further has an α-olefin having 3 to 12 carbon atoms such as propylene, 1-butene, 1-hexene, 1-octene, 4- Ethylene / α-olefin copolymers having one or more structural units derived from methylpentene-1,4-methyl-hexene-1,4,4-dimethyl-pentene-1, etc. (including terpolymers and the like) ). Specific examples of the ethylene / α-olefin copolymer include an ethylene / 1-butene copolymer, an ethylene / 1-octene copolymer, an ethylene-4-methyl-pentene-1 copolymer, an ethylene / butene / hexene copolymer. Center polymers, ethylene / propylene / octene terpolymers, ethylene / butene / octene terpolymers, and the like. The content of the α-olefin in the ethylene / α-olefin copolymer is preferably 5 to 40% by mass, more preferably 10 to 35% by mass, and still more preferably 15 to 30% by mass. If the α-olefin content is small, the solar cell encapsulant may not have sufficient flexibility and impact resistance, and if it is too much, the heat resistance may be low.

  In the present invention, the ethylene / α-olefin copolymer may be one produced using a Ziegler-Natta catalyst or a metallocene catalyst. It is preferable to use a polymer (hereinafter also referred to as m-LLDPE). An ethylene / α-olefin copolymer polymerized with a metallocene catalyst has a sharp molecular weight distribution and is excellent in processability.

  As the metallocene catalyst, a known metallocene catalyst may be used, and there is no particular limitation. The metallocene catalyst is generally a compound having a structure in which a transition metal such as titanium, zirconium or hafnium is sandwiched between unsaturated cyclic compounds containing a π-electron cyclopentadienyl group or a substituted cyclopentadienyl group. And a promoter such as an aluminum compound such as alkylaluminoxane, alkylaluminum, aluminum halide, and alkylaluminum halide. Metallocene catalysts are characterized by a uniform active site (single site catalyst), and usually a polymer having a narrow molecular weight distribution and an approximately equal comonomer content of each molecule is obtained.

In the present invention, the melt flow rate (MFR) of ethylene / α-olefin (according to JIS K7210, 190 ° C., load 2.16 kg) is 0.1 to 15 g / 10 min, preferably 2 to 15 g / 10 min. Preferably it is 2-8g / 10min. In the present invention, the density of m-LLDPE (according to JIS K 7112; the same applies hereinafter) is not particularly limited, but is preferably 0.860 to 0.930 g / cm ³ .

  In the present invention, commercially available m-LLDPE may be used. For example, Harmolex series, Kernel series manufactured by Nippon Polyethylene Co., Ltd., Evolution series manufactured by Prime Polymer Co., Ltd., Excellen GMH series, Excellen FX series manufactured by Sumitomo Chemical Co., Ltd. and the like can be mentioned.

(Ethylene homopolymer)
An ethylene homopolymer is a polymer produced using only ethylene as a raw material monomer. The melt flow rate (MFR) (based on JIS K7210, 190 ° C., load 2.16 kg) of the ethylene homopolymer is 50 to 100 g / 10 min, and preferably 50 to 60 g / 10 min.

The density of the ethylene homopolymer is not particularly limited, but is generally 0.910 to 0.970 g / cm ³ , preferably 0.910 g / cm ³ or more and less than 0.930 g / cm ³ . If it is this range, melting | fusing point will become a favorable range for manufacturing a solar cell sealing material, and workability will become still better.

  In the composition for producing a sealing material for solar cells of the present invention, the mass of the ethylene / α-olefin copolymer relative to the ethylene homopolymer in the resin mixture of the ethylene / α-olefin copolymer and the ethylene homopolymer. The ratio (ethylene / α-olefin copolymer / ethylene homopolymer) is 40/60 to 50/50. If the amount of the ethylene / α-olefin copolymer is too large, the effect of improving the insulation property may not be sufficiently obtained, and if the amount of the ethylene homopolymer is too large, the adhesiveness may not be sufficiently obtained.

[Inorganic filler]
The inorganic filler that is appropriately added in the present invention is used for coloring the sealing material for solar cells. In the present invention, a non-metallic inorganic filler is used. Thereby, even if an inorganic filler is added, the sealing material for solar cells whose insulation property does not fall can be obtained. Examples of non-metallic inorganic fillers include calcium carbonate, kaolin, silica and the like, which are appropriately selected according to the desired color and color intensity. When adding an inorganic filler, the content is generally 0.1 to 50 parts by mass with respect to 100 parts by mass of the resin mixture.

  In particular, when calcium carbonate is contained, the content of calcium carbonate is 50 parts by mass or less, preferably 5 to 50 parts by mass with respect to 100 parts by mass of the resin mixture. If it is this range, the sealing material for solar cells can be colored, maintaining the adhesiveness as a sealing material for solar cells well.

  Moreover, when kaolin is contained, the content of kaolin is 5 parts by mass or less, particularly 0.1 to 5 parts by mass with respect to 100 parts by mass of the resin mixture. If it is this range, the sealing material for solar cells can be colored, maintaining the adhesiveness as a sealing material for solar cells well.

  Although the average particle diameter of an inorganic filler is not specifically limited, For example, it is 1-50 micrometers. The average particle diameter refers to a median diameter determined by a laser diffraction / scattering particle size distribution measurement method. When an inorganic filler is added to color the solar cell encapsulant, it is used as a back surface solar cell encapsulant.

[Crosslinking agent]
The composition for producing a sealing material for solar cells of the present invention preferably contains a crosslinking agent to form a crosslinked structure of an ethylene / α-olefin copolymer and an ethylene homopolymer. As the crosslinking agent, an organic peroxide or a photopolymerization initiator is preferably used. Among them, it is preferable to use an organic peroxide because a sealing material with improved temperature dependency of adhesive strength, moisture resistance, and penetration resistance can be obtained.

  Any organic peroxide can be used as long as it decomposes at a temperature of 100 ° C. or higher to generate radicals. The organic peroxide is generally selected in consideration of the film formation temperature, the adjustment conditions of the composition, the curing temperature, the heat resistance of the adherend, and the storage stability. In particular, those having a decomposition temperature of 70 hours or more with a half-life of 10 hours are preferred.

  Examples of the organic peroxide include, from the viewpoint of resin processing temperature and storage stability, for example, benzoyl peroxide curing agent, tert-hexyl peroxypivalate, tert-butyl peroxypivalate, 3, 5, 5- Trimethylhexanoyl peroxide, di-n-octanoyl peroxide, lauroyl peroxide, stearoyl peroxide, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, succinic acid peroxide, 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane, 2,5-dimethyl-2,5-di (2-ethylhexanoylperoxy) hexane, 1-cyclohexyl-1-methylethyl Peroxy-2-ethylhexanoate, tert-hexyl par Xyl-2-ethylhexanoate, 4-methylbenzoyl peroxide, tert-butylperoxy-2-ethylhexanoate, m-toluoyl + benzoyl peroxide, benzoyl peroxide, 1,1-bis (tert-butyl Peroxy) -2-methylcyclohexanate, 1,1-bis (tert-hexylperoxy) -3,3,5-trimethylcyclohexanate, 1,1-bis (tert-hexylperoxy) cyclohexanate 1,1-bis (tert-butylperoxy) -3,3,5-trimethylcyclohexane, 1,1-bis (tert-butylperoxy) cyclohexane, 1,1-bis (tert-hexylperoxy)- 3,3,5-trimethylcyclohexane, 2,2-bis (4,4-di tert-butylperoxycyclohexyl) propane, 1,1-bis (tert-butylperoxy) cyclododecane, tert-hexylperoxyisopropyl monocarbonate, tert-butylperoxymaleic acid, tert-butylperoxy-3, 3,5-trimethylhexane, tert-butylperoxylaurate, 2,5-dimethyl-2,5-di (methylbenzoylperoxy) hexane, tert-butylperoxyisopropylmonocarbonate, tert-butylperoxy-2 -Ethylhexyl monocarbonate, tert-hexyl peroxybenzoate, 2,5-di-methyl-2,5-di (benzoylperoxy) hexane, and the like.

  As the benzoyl peroxide-based curing agent, any can be used as long as it decomposes at a temperature of 70 ° C. or higher to generate radicals, and those having a decomposition temperature of 50 hours or higher with a half-life of 10 hours are preferable, It can be appropriately selected in consideration of preparation conditions, film formation temperature, curing (bonding) temperature, heat resistance of the adherend, and storage stability. Usable benzoyl peroxide curing agents include, for example, benzoyl peroxide, 2,5-dimethylhexyl-2,5-bisperoxybenzoate, p-chlorobenzoyl peroxide, m-toluoyl peroxide, 2, Examples include 4-dichlorobenzoyl peroxide and t-butyl peroxybenzoate. The benzoyl peroxide curing agent may be used alone or in combination of two or more.

  As the organic peroxide, 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane or tert-butylperoxy-2-ethylhexyl monocarbonate is particularly preferable. Thereby, the sealing material for solar cells which is bridge | crosslinked favorably and has the outstanding transparency is obtained.

  The content of the organic peroxide used in the composition for producing a solar cell encapsulant is preferably 0.1 to 5 parts by mass, more preferably 0.2 to 3 parts per 100 parts by mass of the resin mixture. It is preferable that it is a mass part. If the content of the organic peroxide is small, the crosslinking speed may be lowered during the crosslinking and curing, and if the content is large, the compatibility with the copolymer may be deteriorated.

  As the photopolymerization initiator, any known photopolymerization initiator can be used, but a photopolymerization initiator having good storage stability after blending is desirable. Examples of such a photopolymerization initiator include 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, and 2-methyl-1- (4- (methylthio) phenyl). Acetophenones such as 2-morpholinopropane-1, benzoins such as benzyldimethylketal, benzophenones such as benzophenone, 4-phenylbenzophenone and hydroxybenzophenone, thioxanthones such as isopropylthioxanthone and 2-4-diethylthioxanthone, As other special ones, methylphenylglyoxylate can be used. Particularly preferably, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- (4- (methylthio) phenyl) -2-morpholinopropane-1, Examples include benzophenone. These photopolymerization initiators may contain one or two or more kinds of known and commonly used photopolymerization accelerators such as benzoic acid-based or tertiary amine-based compounds such as 4-dimethylaminobenzoic acid as required. Can be mixed and used. Moreover, it can be used individually by 1 type of only a photoinitiator, or 2 or more types of mixture.

  Content of the said photoinitiator is 0.1-5 mass parts with respect to 100 mass parts of said resin mixtures, Preferably it is 0.2-3 mass parts.

[Crosslinking aid]
It is preferable that the composition for manufacturing a sealing material for solar cells of the present invention further contains a crosslinking aid. The crosslinking aid can improve the gel fraction of the resin of the resin mixture and improve the adhesiveness and weather resistance of the solar cell sealing material.

  The content of the crosslinking aid is usually 0.1 to 5 parts by mass, preferably 0.1 to 3 parts by mass, and particularly preferably 0.5 to 2.5 parts by mass with respect to 100 parts by mass of the resin mixture. used. Thereby, the sealing material which the hardness after bridge | crosslinking improved further is obtained.

  Examples of the crosslinking aid (compound having a radical polymerizable group as a functional group) include trifunctional crosslinking aids such as triallyl cyanurate and triallyl isocyanurate, and (meth) acrylic esters (eg, NK ester) ) Monofunctional or bifunctional crosslinking aids. Of these, triallyl cyanurate and triallyl isocyanurate are preferable, and triallyl isocyanurate is particularly preferable.

[Adhesion improver]
The composition for producing a sealing material for solar cell of the present invention may further contain an adhesion improver. As the adhesion improver, a silane coupling agent can be used. Thereby, it can be set as the sealing material for solar cells which has the further outstanding adhesive force. Examples of the silane coupling agent include γ-chloropropyltrimethoxysilane, vinyltriethoxysilane, vinyltris (β-methoxyethoxy) silane, γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, and γ-glycidoxypropyl. Trimethoxysilane, γ-glycidoxypropyltriethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, vinyltrichlorosilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N Mention may be made of -β- (aminoethyl) -γ-aminopropyltrimethoxysilane. These silane coupling agents may be used alone or in combination of two or more. Of these, γ-methacryloxypropyltrimethoxysilane is particularly preferred.

  The content of the silane coupling agent in the composition for producing a solar cell sealing material of the present invention is 5 parts by mass or less, preferably 0.1 to 2 parts by mass with respect to 100 parts by mass of the resin mixture. preferable.

[Others]
The composition for producing a sealing material for solar cells of the present invention improves or adjusts various physical properties of a film (optical properties such as mechanical strength and transparency, heat resistance, light resistance, crosslinking speed, etc.), especially a machine. Various additives such as a plasticizer, an anti-yellowing agent, an acryloxy group-containing compound, a methacryloxy group-containing compound, and / or an epoxy group-containing compound may be further included as necessary for improving the mechanical strength.

[Sealant for solar cell]
What is necessary is just to perform according to a well-known method in order to form the sealing material for solar cells of this invention. For example, the composition for producing a sealing material for solar cells of the present invention containing each of the above-described components is produced by a method of obtaining a sheet-like material by molding by ordinary extrusion molding or calendar molding (calendering) or the like. Can do. The thickness of the solar cell sealing material of the present invention is not particularly limited, but is 0.05 to 2 mm, preferably 0.3 to 0.8 mm.

[Solar cell module]
The structure of the solar cell module of the present invention is not particularly limited as long as it includes a structure manufactured by sealing a solar cell element using the solar cell sealing material of the present invention. For example, a solar cell element (single crystal or polycrystalline silicon cell or the like) is formed by crosslinking and integrating the solar cell sealing material of the present invention between the front surface side transparent protective member and the back surface side protective member. Examples include a sealed structure.

  In the present invention, the side of the solar cell element irradiated with light (front side) is referred to as “front side”, and the side opposite to the light receiving surface of the solar cell element is referred to as “back side”.

  In the solar cell module, in order to sufficiently seal the solar cell element, for example, as shown in FIG. 1, the front surface side transparent protective member 11, the front surface side solar cell sealing material 13A, the solar cell element 14, the back side solar cell What is necessary is just to laminate | stack the battery sealing material 13B and the back surface side protection member 12, and bridge-harden the surface side sealing material 13A and the back surface side solar cell sealing material 13B according to a conventional method, such as heating and pressurization.

In order to heat and pressurize, the laminated body which laminated | stacked each member is 135-180 degreeC with a vacuum laminator, Furthermore, 140-180 degreeC, Deaeration time 0.1-5 minutes, Press pressure 0.1-1. What is necessary is just to heat-press in 5 kg / cm < ² > and press time for 5-15 minutes.

  At the time of this heating and pressurization, the ethylene / α-olefin copolymer and polyethylene contained in the surface side solar cell encapsulant 13A and the back side solar cell encapsulant 13B are cross-linked, thereby sealing the surface side solar cell. The solar cell 14 can be sealed by integrating the front surface side transparent protective member 11, the back surface side transparent member 12, and the solar cell element 14 via the material 13A and the back surface side solar cell sealing material 13B. In general, the solar cell elements 14 are electrically connected to each other by connection tabs 15.

  The solar cell encapsulant of the present invention is not limited to a solar cell module using a single crystal or polycrystalline silicon crystal solar cell element as shown in FIG. It can also be used as a sealing material for thin film solar cells such as solar cells and copper indium selenide (CIS) solar cells. In this case, for example, the solar cell of the present invention is formed on a thin film solar cell element layer formed by a chemical vapor deposition method or the like on the surface of a surface side transparent protective member such as a glass substrate, a polyimide substrate, or a fluororesin transparent substrate. On the thin-film solar cell element layer formed on the surface of the sealing material for battery, the back side protection member laminated and bonded and integrated, the surface of the back side protection member, the sealing material for solar cell of the present invention, A structure in which a surface-side transparent protective member is laminated and bonded and integrated, or a surface-side transparent protective member, a surface-side sealing material, a thin-film solar cell element, a back-side sealing material, and a back-side protective member are laminated in this order. And a structure in which the adhesive is integrated.

  The surface-side transparent protective member is usually a glass substrate such as silicate glass. As for the thickness of a glass substrate, 0.1-10 mm is common. The glass substrate may be chemically or thermally strengthened.

  For the back side protective member, a plastic film such as polyester such as polyethylene terephthalate (PET) or polyamide is preferably used. Further, a film obtained by laminating a fluorinated polyethylene film, particularly a fluorinated polyethylene film / Al / fluorinated polyethylene film in this order in consideration of heat resistance and wet heat resistance may be used. Further, a glass plate may be used.

  Hereinafter, the present invention will be described with reference to examples.

1. Preparation of Solar Cell Sealant Each material was kneaded at 70 ° C. using a plast mill and a roll mill with the composition shown in the following table to prepare a composition for manufacturing a solar cell sealant. This composition for manufacturing a solar cell encapsulant was calendered at 70 ° C., allowed to cool, and then a sheet-like encapsulant for solar cell (thickness 0.6 mm) was produced.

2. Preparation of cross-linked sample After laminating in the order of PET film (0.5 mm thickness) / the solar cell encapsulant / PET film (0.5 mm thickness), the obtained laminate was subjected to 100 ° C. using a vacuum laminator. After temporarily press-bonding at a temperature for 10 minutes, the sample was placed in an oven and heated for 45 minutes at a temperature of 155 ° C. for crosslinking to obtain a crosslinked sample.

3. Evaluation (1) Adhesive strength to PET With respect to the crosslinked sample, a part between the PET film and the solar cell encapsulant after cross-linking was peeled off, and the solar cell encapsulant was folded 180 ° to obtain a tensile tester. The peeling force at a tensile speed of 100 mm / min was measured as an adhesion force to PET (N / cm) using (Shimadzu Corporation, Autograph).

(2) Volume resistivity (insulation)
The PET film is peeled from the cross-linked sample, the sealing film is taken out, and the applied voltage is measured using a high resistivity meter (Hiresta UP (manufactured by Mitsubishi Chemical)) and a probe (UR-100 (manufactured by Mitsubishi Chemical)). The volume resistivity (Ω · cm) at room temperature was measured under the conditions of 1000 V and heating time of 60 seconds.

(3) Processing temperature range (workability)
In order to evaluate the processing characteristics of each composition obtained, RPA-2000 (manufactured by Alpha Technologies Co., Ltd.) was used to determine the processable temperature range (the range in which the storage elastic modulus is 20 to 100 kPa). It shows that the temperature range which can be processed is so wide that a processing temperature width is wide, and it shows that temperature control at the time of manufacturing a sealing material for solar cells is easy.

The results are shown in the table below. The details of each material are as follows.
Polymer 1: ethylene / α-olefin copolymer polymerized by metallocene catalyst (MFR: 2.2 g / 10 min, density 0.902 g / cm ³ ), product name: Kernel TM KS260 (manufactured by Nippon Polyethylene)
Polymer 2: Ethylene homopolymer (MFR: 55 g / 10 min, density: 0.916 g / cm ³ ) Product name: J6016 (manufactured by Ube Maruzen Polyethylene)
Polymer 3: EVA (MFR: 4.0 g / 10 min, vinyl acetate content: 26% by mass)
Crosslinking agent: 2,5-dimethyl-2,5-di (t-butylperoxy) hexane Silane coupling agent: γ-methacryloxypropyltrimethoxysilane Lubricant: Trialkyl phosphite Yellowing inhibitor: Bis sebacate ( 2,2,6,6-tetramethyl-4-piperidyl)
Inorganic filler 1: Calcium carbonate Inorganic filler 2: Kaolin Inorganic filler 3: Titanium dioxide

<Evaluation results>
When the mass ratio of polymer 1 / polymer 2 was 50/50 to 40/60, it was recognized that the adhesive strength to PET and the volume resistivity were excellent and the processing temperature range was wide. When the content of the polymer 1 was small, it was confirmed that the adhesive strength to PET was not sufficient. It was confirmed that the volume resistivity was not sufficient when the content of polymer 2 was small.

DESCRIPTION OF SYMBOLS 11 Front surface side transparent protective member 12 Back surface side protective member 13A, 13B Solar cell sealing material 14 Solar cell element 15 Connection tab

Claims (8)

An ethylene / α-olefin copolymer having a melt flow rate (conforming to JIS K7210, 190 ° C., load 2.16 kg) of 0.1 to 15 g / 10 min, and a melt flow rate (conforming to JIS K7210, 190 ° C., load) 2.16 kg) comprising a resin mixture with an ethylene homopolymer of 50-100 g / 10 min,
The composition for manufacturing a sealing material for a solar cell, wherein a mass ratio of the ethylene / α-olefin copolymer to the ethylene homopolymer in the resin mixture is 40/60 to 50/50.   The composition for manufacturing a solar cell sealing material according to claim 1, further comprising a non-metallic inorganic filler.   The said inorganic filler is a calcium carbonate, The composition for solar cell sealing material manufacture of Claim 1 or 2 included in the quantity of 5-50 mass parts with respect to 100 mass parts of said resin mixtures.   The said inorganic filler is a kaolin, For the sealing material manufacture for solar cells of any one of Claims 1-3 included in the quantity of 0.1-5 mass parts with respect to 100 mass parts of said resin mixtures. Composition. The composition for manufacturing a sealing material for a solar cell according to any one of claims 1 to 4, wherein a density of the ethylene homopolymer is 0.910 g / cm ³ or more and less than 0.930 g / cm ³ .   The composition for manufacturing a sealing material for a solar cell according to any one of claims 1 to 5, wherein the ethylene / α-olefin copolymer is polymerized using a metallocene catalyst.   The solar cell sealing material formed by shape | molding the solar cell sealing material manufacturing composition of any one of Claims 1-6.   The solar cell module which has a surface side protection member, a solar cell element, and a back surface side protection member, and the said solar cell element is sealed with the sealing material for solar cells of Claim 7.

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